JP2000209866A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the DC component and the even order harmonics of an input current from an AC power supply without increasing the cost and without requiring an intricate adjustment. SOLUTION: A power supply comprises means 10 for detecting the average value of the voltage Vc1 across a smoothing capacitor C1 and outputting a first detection voltage Vk proportional to the average value, and means 11 for detecting the average value of the voltage across a second switching element Q2 and outputting a second detection voltage Vj proportional to the average value. An on/off control section 1 controls the on period of first through fourth switching elements Q1-Q4 to be equalized depending on the first and second detection voltage Vk, Vj. According to the circuitry, the DC component and, the even order harmonics of an input current Is can be suppressed without causing cost increase incident to extra reactance for chopper or extra insulating transformer and without requiring an intricate adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting the output of an AC power supply to a high frequency and supplying it to a load circuit.
In particular, the present invention relates to a power supply device that suppresses a DC component and an even-order harmonic component included in an input current from an AC power supply.

[0002]

2. Description of the Related Art FIG. 29 shows a circuit configuration of a power supply device of a first conventional example. This power supply device includes a series circuit of first and second switch elements that does not block current in the reverse direction, a series circuit of third and fourth switch elements that does not block current in the reverse direction, and a circuit of these two series. Are connected in parallel between both ends of the smoothing capacitor C1, a series circuit of two diodes D5 and D6 connected in anti-parallel between both ends of the smoothing capacitor C1, and a connection point of the first and second switch elements. An AC power supply Vs having one end connected thereto, a first reactor L1 inserted between the other end of the AC power supply Vs and a connection point of the two diodes D5 and D6, and an AC power supply Vs connected to the first and second switch elements. A load circuit Z inserted between the connection point and the connection points of the third and fourth switch elements. However, the first
To fourth switching elements are switching elements Q1 to Q4 each formed of a field effect transistor, and diodes D1 to D4.
Are connected in antiparallel, respectively. Note that parasitic diodes of the first to fourth switching elements Q1 to Q4 are used as the diodes D1 to D4, respectively.

The load circuit Z connects one end of one filament of a discharge lamp FL as a load to a connection point of the first and second switching elements Q1 and Q2, and connects one end of the other filament to one end of an inductor L2. The other end of the inductor L2 is connected to the connection point of the third and fourth switching elements Q3 and Q4, and the capacitor C2 forming a resonance circuit with the inductor L2 is connected between the other ends of both filaments of the discharge lamp FL. Connected to. That is, this power supply device constitutes a discharge lamp lighting device.

[0004] First to fourth switching elements Q1 to Q4
Are turned on and off by control signals S1 to S4 from the control circuit 40. Here, since the low potential side of the smoothing capacitor C1 is grounded, the secondary winding of the transformer is connected between the gate and source of the first and third switching elements Q1, Q3 on the high potential side in each series circuit. The control signals S1 and S3 from the control circuit 40 are applied between the gate and source of the first and third switching elements Q1 and Q3 via a transformer.

The control circuit 40 connects the first and second switching elements Q1 and Q2 connected in series to the AC power supply V.
The control signal S is turned on and off alternately at a frequency higher than the power supply frequency of s (or a cycle shorter than the power supply cycle).
1, S2 and a control signal S4 synchronized with the control signal S1 and a control signal S3 synchronized with the control signal S2.
And the fourth switching element Q4 at the diagonal side of the first switching element Q1 with respect to the load circuit Z.
Is turned on and off in synchronization with the first switching element Q1, and the third switching element Q3 at the diagonal side of the second switching element Q2 with respect to the load circuit Z is synchronized with the second switching element Q2. On and off.
As a result, a high-frequency AC voltage is applied to the load circuit Z, and the discharge lamp FL is lit at a high frequency.

Here, in the above circuit configuration, first to first
The fourth switching elements Q1 to Q4 form a so-called full-bridge type inverter circuit,
And second switching elements Q1, Q2, first reactor L1, diodes D5, D6, smoothing capacitor C1
The step-up chopper circuit is constituted by the above. In other words, the operation of the boost chopper circuit allows the input current Is from the AC power supply Vs to flow in the entire power supply voltage cycle regardless of the level of the voltage Vc1 across the smoothing capacitor C1. No longer occurs, and harmonic components can be suppressed.

The operation of the step-up chopper circuit will be briefly described.

The connection point d of the AC power supply Vs with the first reactor L1 is connected to the first and second switching elements Q1, Q
When the potential of the AC power supply Vs is higher than that of the connection point e with the second switching element Q (hereinafter, the polarity of the AC power supply Vs at this time is positive), the AC power supply Vs → the first A closed circuit of the reactor L1 → the diode D5 → the first switching element Q1 is formed, and energy is stored in the first reactor L1. Then, when the first switching element Q1 is turned off, the energy stored in the first reactor L1 is released in a closed circuit of the first reactor L1, the diode D5, the smoothing capacitor C1, the diode D2, and the AC power supply Vs, and is smoothed. A boost chopper operation for charging C1 is performed.

On the other hand, when the potential at the connection point d is lower than the potential at the connection point e (hereinafter, the polarity of the AC power supply Vs at this time is assumed to be negative), the AC power is supplied while the second switching element Q2 is on. Power supply Vs → second switching element Q2 → diode D6 → first reactor closed circuit is configured
Energy is stored in the reactor L1. When the second switching element Q2 is turned off, the energy stored in the first reactor L1 is changed to the first reactor L1 →
AC power supply Vs → diode D1 → smoothing capacitor C1 →
A boost chopper operation is performed in which the diode D6 is discharged in a closed circuit of the first reactor L1 to charge the smoothing capacitor C1. The current taken in by the boost chopper operation is determined by the length of the ON period of the first and second switching elements Q1 and Q2.

[0010] Here, as shown in FIG.
Of the switching elements Q1 and Q2 are equal and the currents taken in by the boost chopper operation in the positive half cycle and the negative half cycle of the AC power supply Vs are equal, the envelope Is of the input current from the AC power supply Vs is substantially It becomes a sine wave (hereinafter, the envelope of the input current is referred to as “input current Is” unless otherwise specified).

However, as shown in FIG. 31, for example, when the ON period of the first switching element Q1 is shorter than the ON period of the second switching element Q2, the current I _L1 flowing through the first reactor _L1 becomes The amount taken in when the power supply Vs has a positive polarity is smaller than the amount taken in when the power supply Vs has a negative polarity. Therefore, the input current Is is different in the magnitude of the positive and negative, and includes a DC component and an even harmonic component. Also, when the on-period of the second switching element Q2 is shorter than the on-period of the first switching element Q1, the input current Is also includes a DC component and an even harmonic component. The even-order harmonic component causes harmonic interference in the power system, and it is not preferable that the above-mentioned even-order harmonic component is generated with respect to the input current Is.

FIG. 32 is a circuit diagram of a second conventional example described in Japanese Patent Application Laid-Open No. 60-139178. The second conventional example is different from the first conventional example in the configuration of the chopper circuit.
That is, the low potential side of the pulsating current output terminal of the diode bridge DB for full-wave rectifying the AC power supply Vs is connected to the source of the second switching element Q2, and the diode bridge DB
Is connected to the connection point of the first and second switching elements Q1 and Q2 via a diode L5 whose reactor L11 and anode are connected to the reactor L11. The third through the diode D6 connected to the reactor L12
And the fourth switching element Q3, Q4. The configuration and operation of the inverter circuit and the load circuit Z excluding the chopper circuit are common to those of the first conventional example.

Here, the operation of the chopper circuit in Conventional Example 2 will be described.

When the second switching element Q2 is on, the AC power supply Vs → diode bridge DB → reactor L11 → diode D5 → second switching element Q2
When the second switching element Q2 is turned off, the energy stored in the reactor L11 is stored in the reactor L11 → the diode D5 → the diode D1 → the smoothing capacitor C1 → the diode bridge DB → the AC power supply Vs →. The discharged smoothing capacitor C1 is charged by the closed circuit of the reactor L11.

In this conventional example, as shown in FIG. 33, the input current Is is the sum of the current taken by the reactor L11 when the AC power supply Vs has a positive polarity and the current taken by the reactor L12 when the AC power supply Vs has a negative polarity. Therefore, even if the on-period of the second switching element Q2 for performing the chopper operation and the on-period of the fourth switching element Q4 are different in length, the input current Is does not become positive or negative and asymmetrical. No harmonic components are generated. However, there is a problem that two reactors L11 and L12 are required for the chopper circuit, and the cost is increased as compared with the conventional example 1.

FIG. 34 is a circuit diagram of the third conventional example. In the third conventional example, a voltage detection circuit 42 for detecting the voltage Vc1 across the smoothing capacitor C1 in the circuit configuration of the first conventional example,
A PWM control unit 41 that performs PWM control on the first to fourth switching elements Q1 to Q4 so that the voltage Vc1 across the smoothing capacitor C1 becomes constant according to the detection value of the voltage detection circuit 42 is added. . The voltage detection circuit 42
A circuit for detecting a voltage Vj proportional to the both-ends voltage Vc1 by dividing the voltage across the capacitor C3 charged via the diode D7 by the resistors R1 and R2 when the AC power supply Vs has a positive polarity; By dividing the voltage across the capacitor C4 charged via the diode D8 when the voltage is high by the variable resistors R3 and R4, the voltage Vc1
And a switch SW1 that switches between these two types of detection voltages Vj and Vk and outputs the same to the PWM control unit 41. The other configuration is the same as that of the first conventional example, and the description is omitted.

In the third conventional example, the connection point between the first and second switching elements Q1 and Q2 is PWM.
The control section 41 is grounded, and the gate and source of the second switching element Q2 are floating above the ground. Therefore, it is necessary to transmit the control signal S2 between the gate and the source of the second switching element Q2 using an insulating means, and a transformer is used as the insulating means. That is, the gate of the second switching element Q2
The secondary side of the transformer is connected between the sources, and the control signal S2 is applied to the primary side of the transformer. Where PW
The control signal S2 of the square wave output from the M control unit 41 is supplied to the gate of the second switching element Q2 via a transformer.
When transmitted between the sources, the voltage waveform applied between the gate and the source of the second switching element Q2 is distorted as shown in FIG. In this case, the period exceeding the threshold voltage Vth at which the second switching element Q2 is turned on is shorter than the period when the control signal S2 is at the high level, that is, the period when the input voltage on the primary side of the transformer is at the high level. As a result, the ON period of the second switching element Q2 is shorter than the ON period of the first switching element Q1.

Next, the operation of the conventional example will be briefly described. When the AC power supply Vs has a positive polarity, the first switching element Q
1 performs a chopper operation. Here, the length of the ON period of the first switching element Q1 is determined according to the detection value Vj so that the detection value Vj is constant. When the AC power supply Vs has a negative polarity, the second switching element Q2 performs a chopper operation, and the length of the ON period of the second switching element Q2 is such that the detection value Vk is constant according to the detection value Vk. Is determined.

Here, the voltage dividing ratio of the resistors R1 and R2 (= R2
If the resistance values of the variable resistors R3 and R4 are adjusted so that the voltage division ratio (= R3 / (R3 + R4)) of the variable resistors R3 and R4 becomes smaller than / (R1 + R2)), smoothing as shown in FIG. Vj with respect to the voltage Vc1 across the capacitor C1
> Vk. Therefore, the PWM control unit 41 sets the ON period of the second switching element Q2 when the detection voltage Vk is low in the negative polarity of the AC power supply Vs and the ON period of the first switching element Q1 when the AC power supply Vs is in the positive polarity. The ON widths (ON periods) of the control signals S1 and S2 are set and output so as to be longer than the period. Thereby, the gate-source voltage of the second switching element Q2 to which the control signal S2 is transmitted from the PWM control unit 41 via the transformer becomes the second voltage even if the signal waveform is distorted by the transformer as shown in FIG. Threshold voltage Vth of switching element Q2
Is equal to the ON period of the first switching element Q1. Therefore, the input current Is becomes equal between when the AC power supply Vs has the positive polarity and when the AC power supply Vs has the negative polarity, and no even-order harmonic component is generated.

However, the second switching element Q
When the threshold voltage Vth of 2 varies, the division ratio of the variable resistors R3 and R4 must be adjusted each time. Further, even if the characteristic of the ferrite of the core material of the transformer changes due to the ambient temperature and the waveform of the control signal S2 changes, the voltage division ratio of the variable resistors R3 and R4 must be adjusted each time. Further, at least three insulating means (transformers) for transmitting the control signals S2 to the switching elements Q2 are required.

[0021]

In the above-mentioned conventional example 1, the first and second switching elements Q1,
If the length of the ON period of Q2 is different, the waveform of the input current Is changes depending on the polarity of the AC power supply Vs, and as a result, a harmful DC component and even-order harmonic components are generated in the input current Is in the power system. There is a problem.

In the second conventional example, unlike the first conventional example, the first and second switching elements Q that perform the chopper operation are different.
Although no DC component or even-order harmonic component is generated in the input current Is even if the lengths of the ON periods of the Q1 and Q2 are different, the diode bridge DB and the reactor L
11 and L12 must be added, which causes a problem of increasing the cost.

Further, in the above-mentioned conventional example 3, by correcting the control signals S1 and S2 of the first and second switching elements Q1 and Q2 performing the chopper operation, a DC component and an even harmonic component are added to the input current Is. Although it can be prevented from occurring, it is necessary to readjust the correction means (variable resistors R3 and R4) every time the characteristics of the switching element vary, the characteristics change, or the use conditions change. It was not suitable.

The present invention has been made in view of the above problems, and has as its object to reduce the DC component included in the input current from the AC power supply without increasing the cost and without performing complicated adjustments. And a power supply device capable of suppressing even-order harmonic components.

[0025]

According to a first aspect of the present invention, there is provided a power supply system comprising:
And a series circuit of second and third switch elements, and a third and fourth series of switch elements that do not block current in the reverse direction;
These two series circuits are connected in parallel between both ends of a smoothing capacitor, a series circuit of two diodes connected in anti-parallel between both ends of the smoothing capacitor, and a connection point of the first and second switch elements. An AC power supply with one end connected,
A first reactor inserted between the other end of the AC power supply and a connection point of the two diodes, a connection point of the first and second switch elements, and a connection point of the third and fourth switch elements; And a load circuit inserted between the first and second
Are alternately turned on and off at a frequency higher than the power supply frequency of the AC power supply, and the third and fourth switch elements are respectively turned to the second and first positions at diagonal sides.
In a power supply device that supplies high-frequency power to a load circuit by turning on and off in synchronization with a switch element, the first to fourth harmonic components are controlled so as to suppress a DC component and an even harmonic component included in an input current from an AC power supply. It is characterized by comprising a control means for feedback-controlling the on / off of the switch element, and reduces the DC component and even-order harmonic components contained in the input current from the AC power supply without increasing the cost and without complicated adjustment. Can be suppressed.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means detects the first average value detecting means for detecting the average value of the voltage across the smoothing capacitor, and the second switch element on the low potential side. Second average value detecting means for detecting the average value of the voltage between both ends of the first and second average values, and the second average value detected by the second average value detecting means is the first average value detected by the first average value detecting means. Is larger than approximately half of the ON time of the second switch element with respect to the sum of the ON periods of the first switch element and the second switch element, and the second average value is equal to the first average value. Is smaller than substantially half of the first switch element, the first switch element is turned on so that the on-period of the first switch element is made longer with respect to the sum of the on-periods of the first switch element and the second switch element.
And an on / off control means for turning on and off the fourth switch element. In addition to the function of the invention according to claim 1, a DC included in the input current from the AC power supply without detecting the input current can be provided. Components and even-order harmonic components can be suppressed.

According to a third aspect of the present invention, in the first aspect of the present invention, the control means includes a first average value detecting means for detecting an average value of the voltage between both ends of the second switch element on the low potential side; Second average value detection means for detecting the average value of the voltage between both ends of the fourth switch element on the potential side, and the first average value detected by the first average value detection means is used as second average value detection means If the second average value is larger than the second average value, the ON period of the second switch element is lengthened and the ON period of the fourth switch element is shortened so that the first average value is larger than the second average value. On the other hand, it is characterized by comprising on-off control means for turning on and off the first to fourth switch elements so as to shorten the on-period of the second switch element and prolong the on-period of the fourth switch element when it is smaller. And in addition to the function of the invention of claim 1, It is possible to suppress the DC component and even harmonic components in a single circuit configuration.

According to a fourth aspect of the present invention, in the first aspect, the control means determines an average value of a potential difference between a high potential side of the smoothing capacitor and a connection point between the first reactor of the AC power supply. (1) an average value detecting means, a second average value detecting means for obtaining an average value of a potential difference between a low potential side of the smoothing capacitor and a connection point between the first reactor of the AC power supply, and a first average value. When the first average value detected by the detection means is larger than the second average value detected by the second average value detection means, the ON period of the first switch element is shortened and the second switch element is turned off. When the ON period is lengthened and the first average value is smaller than the second average value, the first to the third switch elements are set so as to lengthen the ON period of the first switch element and shorten the ON period of the second switch element. ON / OFF for turning on / off the fourth switch element Characterized by comprising a control means, in addition to the effect of the invention of claim 1, to suppress the DC component and even harmonic components with a simple circuit configuration.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the control means includes a first and a second peak value detecting means for detecting a peak value of a voltage between both ends of the smoothing capacitor; Switching means for switching and inputting the voltage between both ends of the smoothing capacitor to the first and second peak value detecting means, and comparing means for comparing the detection values of the first and second peak value detecting means with each other; The first to fourth switch elements are turned on and off so as to suppress a DC component and an even-order harmonic component included in an input current from an AC power supply according to a comparison result of the comparing means. In addition to the effects of the invention, the DC component and the even harmonic components can be suppressed with a simple circuit configuration.

According to a sixth aspect of the present invention, in the first aspect of the present invention, a first inductor, one end of which is connected to a connection point of the first and second switch elements, and a connection point of the third and fourth switch elements. A load circuit is configured by a parallel circuit of a second inductor having one end connected to the other end, a discharge lamp connected between the other ends of the first and second inductors, and a capacitor for resonance. A first voltage detecting means for detecting a voltage at a connection point between the inductor and the discharge lamp, and a second voltage detecting means for detecting a voltage at a connection point between the second inductor and the discharge lamp; Characterized in that the first to fourth switch elements are turned on and off so as to suppress the DC component and the even-order harmonic component included in the input current from the AC power supply according to the detection value of the second voltage detection means, In addition to the operation of the invention of claim 1, input It is possible to suppress the DC component and even harmonic components in the input current from the AC power supply without detecting the flow.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the control means detects the average value of the current flowing through the first reactor according to the polarity of the AC power supply. Detecting means, and comparing means for comparing the detection values of the first and second current average value detecting means with each other, wherein a DC component contained in an input current from an AC power supply and an even number The first to fourth switch elements are turned on and off so as to suppress the next harmonic component, and the same operation as the invention of claim 1 is achieved.

According to an eighth aspect of the present invention, in the first aspect, the control means includes first and second current peak value detecting means for detecting a peak value of a charging current for charging the smoothing capacitor; Switching means for switching and inputting the voltage between both ends of the smoothing capacitor to the first and second current peak value detecting means according to the polarity, and comparing means for comparing the detection values of the first and second current peak value detecting means with each other And turning on and off the first to fourth switch elements so as to suppress a DC component and an even-order harmonic component included in the input current from the AC power supply according to a comparison result of the comparison means. The same operation as that of the first aspect is achieved.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the control means detects first and second current detecting means for detecting currents flowing through the first and second switch elements, respectively. And a comparing means for comparing the detection value of the second current detecting means, so as to suppress a DC component and an even-order harmonic component contained in the input current from the AC power supply according to the comparison result of the comparing means. The first to fourth switch elements are turned on and off, and in addition to the function of the invention of claim 1, a current flowing through the first and second switch elements due to an input current fluctuation due to a power supply voltage fluctuation of an AC power supply or the like. The DC component and the even-order harmonic component contained in the input current can be suppressed by performing the feedforward control on the first to fourth switch elements.

According to a tenth aspect of the present invention, in the first aspect of the invention, a load circuit is constituted by a discharge lamp, a capacitor connected in parallel to the discharge lamp, and an inductor connected in series with the discharge lamp to form a resonance circuit with the capacitor. The control means detects first and second peak value detecting means for respectively detecting a peak value of a current flowing through the inductor of the load circuit in accordance with the polarity of the AC power supply, and detecting the first and second peak value detecting means. And a first to fourth switch element for suppressing a DC component and an even-order harmonic component included in the input current from the AC power supply according to a comparison result of the comparison means. Are turned on and off, and have the same effect as the first aspect of the invention.

[0035]

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
FIG. In the present embodiment, in the circuit configuration of the first conventional example shown in FIG.
A second average value detecting means 11 for detecting an average value of the voltage between both ends of the second switching element Q2 on the low potential side, and a second average value detected by the second average value detecting means 11 is a first average value. When the average value is larger than half of the first average value detected by the average value detection means 10, the ON period of the second switching element Q2 with respect to the sum of the ON periods of the first switching element Q1 and the second switching element Q2. When the second average value is smaller than approximately half of the first average value, the first to fourth switching operations are performed so as to lengthen the ON period of the first switching element Q1. A different point is that it has an on / off control unit 1 for turning on / off the elements Q1 to Q4, and other configurations and basic operations are the same as those of the conventional example 1. Therefore, common parts are denoted by the same reference numerals. I Description thereof will be omitted.

The first average value detecting means 10 comprises voltage dividing resistors R4 and R5 connected in series between both ends of the smoothing capacitor C1. The voltage Vc1 across the smoothing capacitor C1 is divided by the voltage dividing resistors R4 and R5. Voltage (= Vc1 × R5 / (R4 + R
5)) a voltage Vk proportional to the first average value;
(Hereinafter, referred to as “first detection voltage”). Note that the capacity of the smoothing capacitor C1 is sufficiently large, and the voltage Vc1 between both ends is a substantially constant DC voltage.

Further, the second average value detection means 11
And a series circuit of a resistor R1 and a capacitor C4 inserted between the connection point a of the second switching elements Q1 and Q2 and the ground, and voltage dividing resistors R2 and R3 for dividing a voltage Vc4 across the capacitor C4. . Here, the resistance R1
And the time constant of the capacitor C4 is set to be sufficiently larger than the on / off cycle of the first and second switching elements Q1 and Q2. The average value (second average value) of the voltage between both ends of the element Q2 is obtained. Thus,
The second average value detecting means 11 is a voltage Vj (= Vc4 × R3 / (R2 + R3)) obtained by dividing the voltage Vc4 at both ends and proportional to the second average value. Voltage). Here, R3 / (R2 + R
3) The resistor R2 is set so that = 2 × R5 / (R4 + R5).
To R5 are set. With this setting, when the length of the ON period of the first switching element Q1 is equal to the length of the ON period of the second switching element Q2, the first detection voltage Vk and the second detection voltage Vj become equal to each other. Become equal.

The on / off control unit 1 includes a proportional integrator 2 for proportionally integrating a difference (= Vk−Vj) between the first and second detection voltages Vk and Vj, and a sawtooth wave generator 3 for generating a sawtooth voltage. ,
A comparator CP1 for comparing the output of the proportional integrator 2 with the sawtooth voltage, and a control voltage V
a pull-up resistor Rup that pulls up to cc; and an inverter 5 that inverts the output of the comparator CP1.
And for the fourth switching elements Q1 and Q4, the output of the comparator CP1 is not inverted and the square wave control signal S
1, S4, and control signals S2, S of the square wave obtained by inverting the output of the comparator CP1 with the inverter 5 for the second and third switching elements Q2, Q3.
3 is output. Thus, the first switching element Q1 and the second switching element Q2 are alternately turned on and off by the control signals S1 to S4 output from the on / off control section 1 as described in the conventional example 1, and the first switching element Q2 is turned on and off. The switching element Q4 is turned on / off in synchronization with the first switching element Q1, and the third switching element Q3 is turned on / off in synchronization with the second switching element Q2. Although not shown, the proportional integrator 2 and the comparator CP1
An upper limit clamp circuit that clamps the upper limit of the output of the proportional integrator 2 to a value smaller than the maximum value of the sawtooth voltage;
There is provided a lower limit clamp circuit for clamping the lower limit of the output of the proportional integrator 2 to a value larger than the minimum value of the sawtooth wave voltage.
For example, a dead time generation circuit that generates a dead time by delaying the control signals S1 to S4 is provided so that the switching elements Q1 to Q4 do not turn on at the same time.

Next, the operation of this embodiment will be described.

As shown in FIG. 2, when the ON period T1 of the first and fourth switching elements Q1 and Q4 is shorter than the ON period T2 of the second and third switching elements Q2 and Q3 (when T1 <T2). Case), the potential Va at the connection point a (second
(The voltage across the switching element Q2) becomes equal to the voltage Vc1 across the smoothing capacitor C1 (where Va = Vc1), so that the second detection voltage Vj becomes lower than the first detection voltage Vk. . Therefore, the difference (= Vk−Vj) between the first and second detection voltages Vk and Vj becomes a positive value, and the value obtained by proportionally integrating the difference by the proportional integrator 2 tends to increase. Here, since the output of the proportional integrator 2 is input to the non-inverting side of the comparator CP1 and compared with the sawtooth voltage input to the inverting side of the comparator CP1, the period during which the output of the comparator CP1 is at a high level is long, It changes in such a way that the low level period becomes shorter. Therefore, the ON period T1 of the control signals S1 and S4 for turning on and off the first and fourth switching elements Q1 and Q4 is long, and the control signal S for turning on and off the second and third switching elements Q2 and Q3.
2, the on-period T2 of S3 decreases. If the ON period T1 of the control signals S1 and S4 becomes longer, the connection point a
Is longer than the voltage Vc1 across the smoothing capacitor C1, the second detection voltage Vj increases.

Here, the proportional integrator 2 is configured to output a voltage having a value such that the on-duty of the sawtooth voltage becomes approximately 50% when the input becomes zero. When the detection voltage Vj rises and becomes equal to the first detection voltage Vk, the input of the proportional integrator 2 becomes zero and the comparator CP
The on-duty of the output of No. 1 is also approximately 50%, and is in a stable state.

That is, as shown in FIG.
When the detection voltages Vk and Vj are equal to each other, the potential V
The average value of a is approximately 2 of the voltage Vc1 across the smoothing capacitor C1.
That is, the ON period T1 of the first and fourth switching elements Q1 and Q4 is equal to the ON period T2 of the second and third switching elements Q2 and Q3, and the operation is stabilized. In such a stable state, the positive and negative magnitudes of the input current Is from the AC power supply Vs are substantially the same, and the input current Is does not include a DC component and an even-order harmonic component.

As described above, in this embodiment, the average value of the voltage Vc1 across the smoothing capacitor C1 and the average value of the voltage across the second switching element Q2 are detected, and the first value proportional to the average value is detected. By controlling the on-periods of the first to fourth switching elements Q1 to Q4 according to the second detection voltages Vk and Vj, the cost increases due to the addition of the reactance for the chopper as in the conventional example 2 and the conventional example. 3, it is possible to suppress the generation of the DC component and the even-order harmonic component of the input current Is without increasing the cost due to the addition of the insulating transformer and without performing the complicated adjustment as in the conventional example 3. it can.

The discharge lamp FL has, for example, a ring-shaped fluorescent lamp having a rated lamp voltage of approximately 229 V, a rated lamp current of approximately 0.43 A, and a rated lamp power of approximately 97 W, a rated lamp voltage of approximately 160 V, and a rated lamp current of approximately 0.9 W. A ring-shaped fluorescent lamp having a power of approximately 0.43 A and a rated lamp power of approximately 68 W, or a lamp having an optical path length of approximately 1400 to 2500 mm and a tube diameter of approximately 18 to 29 mm is desirable. Further, in the present embodiment, the inverter circuit is a full-bridge type of the first to fourth switching elements Q1 to Q4. It is particularly suitable for high-frequency lighting of a high-voltage discharge lamp in which a thin tube is a double tube.

(Embodiment 2) FIG. 4 shows a circuit diagram of Embodiment 2. In this embodiment, the first average value detecting means 1 detects the average value of the voltage between both ends of the second switching element Q2.
2 and a second average value detecting means 13 for detecting an average value of the voltage between both ends of the fourth switching element Q4, and the on / off control unit 1 detects the first average value detected by the first average value detecting means 12. Is longer than the second average value Vj detected by the second average value detecting means 13, the ON period of the second switching element Q2 is extended and the ON period of the fourth switching element Q4 is increased. And the first average value V
When i is smaller than the second average value Vj, the first period is set so as to shorten the ON period of the second switching element Q2 and lengthen the ON period of the fourth switching element Q4.
To turn on and off the fourth switching elements Q1 to Q4. Since other configurations and basic operations are common to the first conventional example and the first embodiment, the common parts are denoted by the same reference numerals and description thereof is omitted.

The first average value detection means 12 includes a voltage dividing resistor R1, R2 inserted between the connection point a of the first and second switching elements Q1, Q2 and the ground, and a voltage dividing resistor R2. And outputs a first detection voltage Vi obtained by averaging the voltage drop of the resistor R2 proportional to the voltage between both ends of the second switching element Q2 by the capacitor C10.

Further, the second average value detecting means 13
A voltage dividing resistor R3, R4 inserted between the connection point c of the fourth switching element Q3, Q4 and the ground, and a capacitor C11 connected between both ends of the resistor R4, and the fourth switching element Q4 Obtained by averaging the voltage drop of the resistor R4 proportional to the voltage between both ends of the resistor R4 with the capacitor C11.
Is output. Here, the resistors R1 and R3 and the resistors R2 and R4 have the same resistance value (R
3 = R1, R4 = R2).

The on / off control unit 1 includes a comparator CP2 for comparing the first and second detection voltages Vi and Vj, and control signals S1 to S4 for the first to fourth switching elements Q1 to Q4 according to the output of the comparator CP2. And a control circuit 7 for generating and outputting S4.

Here, the control circuit 7 includes a comparator CP
When the first detection voltage Vi is lower than the second detection voltage Vj (Vi <Vj) according to the comparison result of No. 2 and the first and fourth detection voltages,
The control signals S1 to S4 are output so as to lengthen the on-periods of the switching elements Q1 and Q4 and shorten the on-periods of the second and third switching elements Q2 and Q3. Conversely, the first detection voltage Vi changes to the second detection voltage Vj.
If it is higher (Vi> Vj), the control signal S1 is set so as to shorten the on-periods of the first and fourth switching elements Q1 and Q4 and prolong the on-period of the second and third switching elements Q2 and Q3. To S4. When the first and second detection voltages Vi and Vj are equal, the on-period of the first and fourth switching elements Q1 and Q4 becomes equal to the on-period of the second and third switching elements Q2 and Q3. Operation is stable. In this stable state, the positive and negative magnitudes of the input current Is from the AC power supply Vs are substantially the same, and no DC component and even harmonic components are generated in the input current Is.

The present embodiment has an advantage that the DC component and the even-order harmonic component of the input current Is can be suppressed with a simple configuration as compared with the first embodiment.

(Third Embodiment) FIG. 5 shows a circuit diagram of a third embodiment. Since other configurations and basic operations are common to the first conventional example and the first embodiment, the common parts are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 5, a point is connected between a connection point g between the high potential side of the smoothing capacitor C1 and the first switching element Q1 and a connection point d between the first reactor L1 of the AC power supply Vs. A series circuit of the piezoresistors R1 and R2 and a capacitor C10 connected in parallel with the resistor R2 and averaging the voltage drop of the resistor R2 are connected. A differential amplifier OP for differentially amplifying the voltage Vh across the capacitor C10 and the voltage Vd at the connection point d via the level shift circuits LS1 and LS2, respectively.
1 and the voltage dividing resistors R1 and R2 and the capacitor C10 constitute a first average value detecting means 14. Thus, the voltage between the connection points g and d (= Vh-V) is output from the differential amplifier OP1.
A first detection voltage Vj proportional to d) is output.

A second average value comprising a series circuit of voltage dividing resistors R3 and R4 and a capacitor C11 connected in parallel with the resistor R4 and averaging the voltage drop of the resistor R4 is provided between the connection point d and the ground. A detection means 15 is provided, and a second detection voltage Vi proportional to the voltage between the connection point d and the ground is output between both ends of the capacitor C11. Where the resistance R
1 and R3 and R2 and R4 have the same resistance value (R3 = R1, R4 = R2).

The on / off control section 1 includes a comparator CP3 for comparing the first and second detection voltages Vj and Vi, and control signals S1 to S4 for the first to fourth switching elements Q1 to Q4 according to the output of the comparator CP3. And a control circuit 7 for generating and outputting S4.

Here, the control circuit 7 includes a comparator CP
When the first detection voltage Vj is higher than the second detection voltage Vi (Vi <Vj) according to the comparison result of No. 2, the first and fourth detection voltages are used.
The control signals S1 to S4 are output so as to lengthen the on-periods of the switching elements Q1 and Q4 and shorten the on-periods of the second and third switching elements Q2 and Q3. Conversely, the first detection voltage Vj is changed to the second detection voltage Vi.
When it is lower than (Vi> Vj), the control signal S1 is configured to shorten the on-periods of the first and fourth switching elements Q1 and Q4 and prolong the on-period of the second and third switching elements Q2 and Q3. To S4. When the first and second detection voltages Vj and Vi are equal, the on-period of the first and fourth switching elements Q1 and Q4 becomes equal to the on-period of the second and third switching elements Q2 and Q3. Operation is stable. In this stable state, the positive and negative magnitudes of the input current Is from the AC power supply Vs are substantially the same, and no DC component and even harmonic components are generated in the input current Is.

The present embodiment has an advantage that the DC component and the even-order harmonic component of the input current Is can be suppressed with a simple configuration as compared with the first embodiment.

(Fourth Embodiment) FIG. 6 shows a circuit diagram of a fourth embodiment. Note that the basic configuration and operation of the present embodiment are common to those of the conventional example 1 and the third embodiment.

In this embodiment, instead of detecting the voltage between the connection points g and d, the voltage dividing resistor R for detecting the voltage between the connection point g and the ground (the voltage Vc1 across the smoothing capacitor C1) is used.
The third embodiment differs from the third embodiment in that a first average value detecting means 14 'including 1' and R2 'is provided. However, the partial pressure ratio of the first average value detecting means 14 '(= R2' / (R1 '+ R2'))
Is the partial pressure ratio of the second average value detecting means 15 (= R4 / (R3
+ R4)), the resistances of the resistors R1 'and R2' are set so as to be twice as large.

In the comparator CP3 of the on / off control unit 1, the first detection voltage Vj (the voltage Vc1 across the smoothing capacitor C1) detected by the first average value detection means 14 'is used.
Is compared with the second detection voltage Vi proportional to the voltage between the connection point d and the ground, and the control circuit 7 makes the first and second detection voltages Vj and Vi equal. The same control as in the third embodiment is performed. When the first and second detection voltages Vi and Vj are equal, the on-period of the first and fourth switching elements Q1 and Q4 becomes equal to the on-period of the second and third switching elements Q2 and Q3. Thus, the magnitudes of the positive and negative of the input current Is from the AC power supply Vs are substantially the same, and no DC component and even-order harmonic components are generated in the input current Is.

(Fifth Embodiment) FIG. 7 shows a circuit diagram of a fifth embodiment. In the present embodiment, first and second peak value detection circuits PK1 and PK2 for detecting the peak value of the voltage Vc1 across the smoothing capacitor C1, and the voltage across the smoothing capacitor C1 according to the polarity of the AC power supply Vs are set to the first and second peak values. Switching means for switching and inputting to the second peak value detection circuits PK1 and PK2, and a comparator CP4 for comparing the detection values of the first and second peak value detection circuits PK1 and PK2 with each other,
The control circuit 7 controls the ON period of the first and fourth switching elements Q1 and Q4 and the second period in response to the output of the comparator CP4.
And the first to fourth switching elements Q1 to Q4 such that the on-periods of the third switching elements Q2 and Q3 are equal.
It creates and outputs control signals S1 to S4 for turning on / off Q4. Since other configurations and basic operations are common to the first conventional example and the first embodiment, the common parts are denoted by the same reference numerals and description thereof is omitted.

Voltage dividing resistors R1 and R2 are connected in series between both ends of the smoothing capacitor C1, and a connection point b of the resistors R1 and R2 is connected to a common contact Pc of the switch SW1.
This switch SW1 has a pair of switching contacts P which are switched by a polarity determining circuit 9 for determining the polarity of the AC power supply Vs.
a and Pb, and first and second peak value detection circuits PK1 and PK2 are connected to the respective switching contacts Pa and Pb. Thus, the switch SW1 and the polarity discriminating circuit 9 constitute switching means.

The polarity determining circuit 9 switches the switch SW1 to the switching contact point Pa when the AC power supply Vs has a positive polarity (polarity at which the connection point a side of the first and second switching elements Q1 and Q2 has a high potential). First peak value detection circuit PK1
Is connected to the connection point b, and when the AC power supply Vs has the negative polarity, the switch SW1 is switched to the switching contact Pb to connect the second peak value detection circuit PK2 to the connection point b.

The first and second peak value detection circuits PK1,
PK2 holds the peak value of the voltage Vb at the connection point b obtained by dividing the voltage Vc1 across the smoothing capacitor C1 by the voltage dividing resistors R1 and R2 with a time constant that is several times or more longer than the power supply cycle of the AC power supply Vs. It is.

By the way, as shown in FIG. 8B, when the input current Is is biased depending on the polarity of the AC power supply Vs,
The voltage Vb proportional to the voltage Vc1 across the smoothing capacitor C1
Of the first peak value detection circuit PK1 and the bias value of the first peak value detection circuit PK1,
The detection voltage Vd of the second peak value detection circuit PK2 will be different. Conversely, if the peak value of the voltage Vb is constant regardless of the polarity of the AC power supply Vs, the first and second detection voltages Vc and Vd become equal.

Therefore, when the output of the comparator CP4 is at a high level (the first detection voltage Vc> the second detection voltage Vd), the input current Is increases when the AC power supply Vs has a positive polarity. The circuit 7 generates and outputs control signals S1 to S4 so as to shorten the on-period of the first and fourth switching elements Q1 and Q4 and prolong the on-period of the second and third switching elements Q2 and Q3. I do. Conversely, when the output of the comparator CP4 is at a low level (first detection voltage Vc <second detection voltage Vd), the input current Is increases when the AC power supply Vs has a negative polarity. Increases the on-period of the first and fourth switching elements Q1 and Q4 and
And generating and outputting control signals S1 to S4 so as to shorten the on-periods of the third switching elements Q2 and Q3.
That is, in the control circuit 7, the control signal S for controlling the on / off of the first to fourth switching elements Q1 to Q4 so that the first detection voltage Vc and the second detection voltage Vd become equal.
Since 1 to S4 are created and output, the bias of the input current Is according to the polarity of the AC power supply Vs is eliminated, and the input current Is does not include a DC component and an even harmonic component.

(Embodiment 6) FIG. 9 shows a circuit diagram of Embodiment 6. Note that the basic configuration and operation of the present embodiment are common to those of the first conventional example and the first embodiment, and therefore, the common parts are denoted by the same reference numerals and description thereof is omitted.

In this embodiment, the first current-limiting inductor L21 having one end connected to the connection point of the first and second switching elements Q1 and Q2, and the connection of the third and fourth switching elements Q3 and Q4. A current limiting second inductor L22 having one end connected to a point, first and second inductors L21, L21,
A load circuit Z is constituted by a parallel circuit of the discharge lamp FL and the capacitor C2 for resonance connected between the other ends of L22. The first and second inductors L21 and L22 may be wound around separate cores or may be wound around the same core.

Also, the first inductor L21 and the discharge lamp FL
Voltage detecting means 16 for detecting the maximum value of the voltage Vb1 with respect to the ground at the connection point b1 of the first and second inductors L1 and L2.
22 and the voltage V with respect to the ground at the connection point b2 of the discharge lamp FL
and a second voltage detecting means 17 for detecting the maximum value of b2. These first and second voltage detecting means 16 and 17 are provided.
Are input to the on / off control unit 1.

Since the first and second voltage detecting means 16 and 17 have substantially the same configuration, only the first voltage detecting means 16 will be described. First voltage detecting means 16
Is a voltage dividing resistor R inserted between the connection point b1 and the ground.
1 and a parallel circuit of a capacitor C4 and a resistor R3 charged via a diode D7 from a connection point of R2, and a voltage Vj (hereinafter, referred to as a "first voltage") proportional to the maximum value of the voltage b1 is provided across the capacitor C4. Is referred to as “detection voltage”). Here, since the first and second inductors L21 and L22 are connected to the respective filaments of the discharge lamp FL, the voltage Vb1 at the connection point b1 is half of the voltage Vc1 across the smoothing capacitor C1 and the voltage Vc1 of the discharge lamp FL. Vb1 = (Vc1 + VLa) / 2, which is the sum of half the lamp voltage VLa. The voltage Vb2 at the connection point b2 is equal to the voltage Vc1 across the smoothing capacitor C1.
Vb1 is the difference between half of the discharge lamp FL and half of the lamp voltage VLa of the discharge lamp FL.
= (Vc1 -VLa) / 2.

Next, the operation of this embodiment will be described.

As shown in FIG. 10, the ON periods T1 of the first and fourth switching elements Q1 and Q4 are the second and third switching elements Q1 and Q4.
Is shorter than the ON period T2 of the switching elements Q2 and Q3 (when T1 <T2), a negative DC voltage is superimposed on the lamp voltage VLa, and the positive / negative balance is lost. Therefore, the waveforms of the voltages Vb1 and Vb2 are also different, and the maximum value (first detection voltage) Vj of the voltage Vb1 detected by the first voltage detection means 16 is the voltage Vj detected by the second voltage detection means 17.
It becomes lower than the maximum value (second detection voltage) Vk of b2. Therefore, the difference between the first and second detection voltages Vj and Vk (= Vk
−Vj) becomes a positive value, and the value obtained by proportionally integrating the difference by the proportional integrator 2 tends to increase. Here, since the output of the proportional integrator 2 is input to the non-inverting side of the comparator CP1 and compared with the sawtooth voltage input to the inverting side of the comparator CP1, the period during which the output of the comparator CP1 is at a high level is long, It changes in such a way that the low level period becomes shorter. Therefore, the first and fourth switching elements Q1, Q
4, the on-period T1 of the control signals S1 and S4 for turning on and off the switching element 4 is long, and the on-period T2 of the control signals S2 and S3 for turning on and off the second and third switching elements Q2 and Q3 is shortened.

Thus, as shown in FIG.
Are equal to the maximum value of the voltage Vb2 when the detection voltages Vj and Vk are equal, that is, the on-period T1 of the first and fourth switching elements Q1 and Q4 and the second and third switching elements Q2 , Q3 have the same ON period T2, and the operation is stabilized. In such a stable state, the DC component is not superimposed on the lamp voltage VLa of the discharge lamp FL, the magnitudes of the positive and negative of the input current Is from the AC power supply Vs are substantially the same, and the DC current and the even-order No harmonic components are generated.

(Seventh Embodiment) FIG. 12 is a circuit diagram of a seventh embodiment. In the present embodiment, the first and second AC power sources Vs
Current average value detecting means 18 for detecting the average value of the current flowing through the first reactor L1 when the connection point between the switching element Q1 and the switching element Q2 becomes a positive electrode;
a second current average value detecting means 1 for detecting an average value of a current flowing through the first reactor L1 when a connection point between the first and second switching elements Q1 and Q2 is negative.
9 and a comparator CP5 for comparing the detection values of the first and second current average value detection means 18 and 19 with each other,
The control circuit 7 controls the ON period of the first and fourth switching elements Q1, Q4 and the second
And the first to fourth switching elements Q1 to Q4 such that the on-periods of the third switching elements Q2 and Q3 are equal.
It creates and outputs control signals S1 to S4 for turning on / off Q4. Since other configurations and basic operations are the same as those of the first conventional example, the same parts are denoted by the same reference numerals and the description thereof is omitted.

The first and second current average value detecting means 18,
Reference numeral 19 denotes diodes D10 and D11 at both ends of a secondary winding n2 for input current detection provided in the first reactor L1.
Connected through. The center of the secondary winding n2 is connected to the ground. Thus, the first current average value detecting means 18 has a time constant that is several times or more longer than the power supply frequency of the AC power supply Vs, and responds to the average value of the detected current when the AC power supply Vs has the positive polarity. The first detection voltage Vi is output, and the second current average value detection means 19 outputs the AC power supply V
A second detection voltage Vj having a time constant several times or more longer than the power supply frequency of s and corresponding to the average value of the detection current when the AC power supply Vs has a negative polarity is output.

Here, the control circuit 7 includes a comparator CP
When the first detection voltage Vi is higher than the second detection voltage Vj (Vi> Vj) according to the comparison result of 5, the first and fourth detection voltages are used.
The control signals S1 to S4 are output so as to lengthen the on-periods of the switching elements Q1 and Q4 and shorten the on-periods of the second and third switching elements Q2 and Q3. Conversely, the first detection voltage Vi changes to the second detection voltage Vj.
When it is lower than (Vi <Vj), the control signal S1 is configured to shorten the on-periods of the first and fourth switching elements Q1 and Q4 and prolong the on-period of the second and third switching elements Q2 and Q3. To S4. When the first and second detection voltages Vi and Vj are equal, the on-period of the first and fourth switching elements Q1 and Q4 becomes equal to the on-period of the second and third switching elements Q2 and Q3. Operation is stable. In this stable state, the positive and negative magnitudes of the input current Is from the AC power supply Vs are substantially the same, and no DC component and even harmonic components are generated in the input current Is.

As shown in FIG. 13, the third and fourth
Switching elements Q3, Q4 and smoothing capacitor C
By connecting a series circuit of capacitors C20 and C21 in parallel with the first and second switching elements Q1 and Q2 instead of 1, even if a half-bridge type inverter circuit is configured, the same operation and effect as described above can be obtained. Play.

(Eighth Embodiment) FIG. 14 shows a circuit diagram of the eighth embodiment. In the present embodiment, the first and second current peak value detection circuits PK1 and PK2 for detecting the peak value of the charging current for charging the smoothing capacitor C1, and the voltage across the smoothing capacitor C1 according to the polarity of the AC power supply Vs. First and second
And a comparator CP4 for comparing the detection values of the first and second current peak value detection circuits PK1 and PK2 with each other. The first and fourth switching elements Q1 and Q4 according to the output of the comparator CP4
4 and the second and third switching elements Q2,
Control signals S1 to S4 for turning on and off the first to fourth switching elements Q1 to Q4 so that the on-period of Q3 is equal.
S4 is created and output. Since other configurations and basic operations are common to the first conventional example and the first embodiment, the common parts are denoted by the same reference numerals and description thereof is omitted.

The primary side of the current transformer CT is inserted on the high potential side of the smoothing capacitor C1, and the shunt resistor R1 and the capacitor C10 for filtering high-frequency pulses are provided on the secondary side of the current transformer CT via the diode D10. And a connection point b between the resistor R1 and the cathode of the diode D10 is connected to the common contact Pc of the switch SW1. The switch SW1 has a pair of switching contacts Pa and Pb that are switched by a polarity determination circuit 9 that determines the polarity of the AC power supply Vs.
First and second peak value detection circuits PK1 and PK2 are connected to the respective switching contacts Pa and Pb. Thus, the switch S
Switching means is constituted by W1 and the polarity determination circuit 9.

The polarity determining circuit 9 switches the switch SW1 to the switching contact point Pa when the AC power supply Vs has a positive polarity (polarity at which the connection point a side of the first and second switching elements Q1 and Q2 has a high potential). First peak value detection circuit PK1
Is connected to the connection point b, and when the AC power supply Vs has the negative polarity, the switch SW1 is switched to the switching contact Pb to connect the second peak value detection circuit PK2 to the connection point b.

The first and second peak value detection circuits PK1,
PK2 is a resistor R1 based on the secondary current of the current transformer CT corresponding to the charging current flowing into the smoothing capacitor C1.
, That is, the peak value of the voltage Vb at the connection point b is held at a time constant that is several times or more longer than the power supply cycle of the AC power supply Vs.

By the way, as shown in FIG. 15B, when the input current Is is biased according to the polarity of the AC power supply Vs, the voltage Vb is proportional to the charging current of the smoothing capacitor C1.
Of the first peak value detection circuit PK1 and the bias value of the first peak value detection circuit PK1,
The detection voltage Vd of the second peak value detection circuit PK2 will be different. Conversely, if the peak value of the voltage Vb is constant regardless of the polarity of the AC power supply Vs, the first and second detection voltages Vc and Vd become equal.

Therefore, when the output of the comparator CP5 is at a high level (the first detection voltage Vc> the second detection voltage Vb), the input current Is increases when the AC power supply Vs has a positive polarity. The circuit 7 generates and outputs control signals S1 to S4 so as to shorten the on-period of the first and fourth switching elements Q1 and Q4 and prolong the on-period of the second and third switching elements Q2 and Q3. I do. Conversely, when the output of the comparator CP4 is at a low level (the first detection voltage Vc <the second detection voltage Vb), the input current Is increases when the AC power supply Vs has a negative polarity. Increases the on-period of the first and fourth switching elements Q1 and Q4 and
And generating and outputting control signals S1 to S4 so as to shorten the on-periods of the third switching elements Q2 and Q3.
That is, in the control circuit 7, the control signal S for controlling the on / off of the first to fourth switching elements Q1 to Q4 so that the first detection voltage Vc and the second detection voltage Vd become equal.
Since 1 to S4 are created and output, the bias of the input current Is according to the polarity of the AC power supply Vs is eliminated, and the input current Is does not include a DC component and an even harmonic component.

Ninth Embodiment FIG. 16 is a circuit diagram of a ninth embodiment. In the present embodiment, a current detection circuit 20 for detecting currents (input current Is) flowing through the first and second switching elements Q1 and Q2 performing the chopper operation is compared with two detection values of the current detection circuit 20. And a first to fourth switch element for suppressing a DC component and an even-order harmonic component included in the input current Is from the AC power supply Vs according to a comparison result of the comparison unit. Things.

FIG. 17 shows a specific circuit configuration of the current detection circuit 20.
Shown in A detection resistor Rs is inserted between the AC power supply Vs and a connection point between the first and second switching elements Q1 and Q2.
When the first switching element Q1 is turned on when the first switching element Q1 is turned on, the first current mirror section CM1 includes the transistors Q13, Q14 and the resistor R3. The operating second current mirror unit CM2 is connected to each other. Also, the first and second current mirror units CM
A third current mirror unit CM3 including transistors Q15 and Q16 is connected to the output side of the first and CM2 via a resistor R4. Further, an output circuit 21 including a transistor Q17, a resistor R5, and the like is provided on the output side of the third current mirror unit CM3.

The collector of the transistor Q16 on the output side of the third current mirror unit CM3 is connected to the connection point of the bias resistors R5 and R6 of the output circuit 20. The bias resistors R5 and R6 divide the control power supply Vcc to bias the transistor Q17. The collector of the output transistor Q17 is connected to the control power supply Vcc via the resistor R8, and the output resistor R9 is connected between the collector and the emitter. Thus, a detection voltage Vo corresponding to the current flowing through the transistor Q17 is output to both ends of the resistor R9.

Next, the operation of the current detection circuit 20 will be described.
First, when the first switching element Q1 is turned on, the input current Is flows to the detection resistor Rs in the leftward direction (positive direction) in FIG. 17, so that the transistors Q11 and Q12 operate due to the voltage drop generated in the detection resistor Rs, and A current determined by R2 flows. That is, the first current mirror unit CM1 operates to supply a current to the third current mirror unit CM3 via the resistor R4. Here, the third
The current corresponding to the output current of the first current mirror unit CM1, that is, the current corresponding to the input current Is flowing to the detection resistor Rs, flows to the output side of the current mirror unit CM3, so that the transistor Q17 in the output circuit 20 is turned off, The current flowing through R9 increases. As a result, the output circuit 2
From 0, a detection voltage Vo of a level corresponding to the input current Is is output.

Conversely, when the second switching element Q2 is turned on, the input current Is flows to the detection resistor Rs in the right direction (negative direction) in FIG. Then, a current determined by the resistor R3 flows. That is, the second current mirror unit CM2 operates to supply a current to the third current mirror unit CM3 via the resistor R4.
As a result, as described above, the input current I
A detection voltage Vo of a level corresponding to s is output.

Here, an on / off control unit (not shown)
The detection voltage Vo during the on-period of the first switching element Q1 is compared with the detection voltage Vo during the on-period of the second switching element Q2 in synchronization with the control signals S1 and S2, and for example, the on-state of the first switching element Q1 is turned on. If the detection voltage Vo in the period is higher than the detection voltage Vo in the ON period of the second switching element Q2, the on-duty of the control signals S1 and S4 is reduced to make the first and fourth control signals S1 and S4 smaller.
By shortening the on-periods of the switching elements Q1 and Q4 and increasing the on-duty of the control signals S2 and S3 to prolong the on-periods of the second and third switching elements Q2 and Q3, the above two types of detection can be performed. The first to fourth switching elements Q1 to Q4 are set so that the voltages Vo are equal.
The ON period of Q4 is controlled. Thus, the variation of the input current Is due to the polarity of the AC power supply Vs is reduced, and the DC component and even-order harmonic components of the input current Is can be suppressed. Further, there is an advantage that a current flowing in the positive and negative two directions with respect to the first and second switching elements Q1 and Q2 can be easily detected, and even-order harmonic components can be stably suppressed.

(Embodiment 10) FIG. 18 shows a specific circuit diagram of the detection circuit 20 in Embodiment 10. The circuit configuration and operation other than the detection circuit 20 are the same as those of the ninth embodiment, so that illustration and description are omitted.

The detection circuit 20 of the present embodiment is similar to the detection circuit of the ninth embodiment.
Of the first and second current mirror units CM1 and CM2 in the detection circuit 20 of FIG.
The feature is that M4 is connected between both ends of the detection resistor Rs. The fourth current mirror unit CM4 includes transistors Q11 and Q12 whose bases are connected to each other, a diode D10 having a cathode connected to the emitter of the transistor Q12, and an anode connected to both ends of the detection resistor Rs. It comprises D11 and diodes D12 and D13 whose anodes are connected to the collector of the transistor Q11 via a resistor R2 and whose cathodes are connected to both ends of the detection resistor Rs.

When the first switching element Q1 is turned on, the input current Is flows in the positive direction through the detection resistor Rs, and the transistors Q11 and Q12 operate due to the voltage drop generated in the detection resistor Rs, and the transistors Q11 and Q12 operate via the diode D11. The current determined by the resistor R2 flows through the transistors Q10 and Q11 and the diode D12, and the third current flows through the resistor R4.
The current is supplied to the current mirror unit CM3. Conversely, when the second switching element Q2 turns on, the detection resistor R
s, the input current Is flows in the negative direction, and the transistors Q11 and Q12 operate due to the voltage drop across the detection resistor Rs.
A current determined by the resistor R2 flows through the transistor D11 and Q12 and the diode D13 via the diode D10, and the current is supplied to the third current mirror unit CM3 via the resistor R4. As a result, as described in the ninth embodiment, the output circuit 20 outputs the detection voltage Vo at a level corresponding to the input current Is.

Then, a detection voltage Vo during the on-period of the first switching element Q1 and a detection voltage Vo during the on-period of the second switching element Q2 are synchronized by an on / off control unit (not shown) in synchronization with the control signals S1 and S2. By comparing the on-periods of the first to fourth switching elements Q1 to Q4 so that the two types of detection voltages Vo become equal, the input current Is depending on the polarity of the AC power supply Vs is obtained.
And the DC component and the even harmonic component of the input current Is can be suppressed.

As described above, in the present embodiment, the ninth embodiment is used.
As compared with the above, there is an advantage that the circuit configuration can be simplified and the cost can be reduced, and the even harmonic component of the input current Is can be suppressed stably.

(Embodiment 11) FIG. 19 shows a specific circuit diagram of the detection circuit 20 in Embodiment 11. The circuit configuration and operation other than the detection circuit 20 are the same as those of the ninth embodiment, so that illustration and description are omitted.

The difference between the detection circuit 20 of the present embodiment and the detection circuit 20 of the ninth embodiment is that the second current mirror section C
This is the point that M2 is omitted and the circuit configuration of the output circuit 22. The output circuit 22 is the output circuit 21 according to the ninth embodiment.
In contrast to the configuration of (1), the anode of the diode D15 is connected to one end of the resistor R9 on the high potential side, and the output resistor R10 is connected to the cathode of the diode D15 and one end of the low potential side of the resistor R9. A resistor R11 and a diode D14 are connected in series between a connection point between Rs and the resistor R2 and a connection point between the diode D15 and the resistor R10.

When the first switching element Q1 is turned on, a positive input current Is flows through the detection resistor Rs, and the transistors Q11 and Q12 operate due to a voltage drop across the detection resistor Rs, and are determined by the resistor R2. The current flows through the transistors Q11 and Q12, and the current is supplied to the third current mirror unit CM3 via the resistor R4. Then, the transistor Q17 in the output circuit 22 turns off, and the current flowing through the resistor R10 via the diode D15 increases. As a result, a detection voltage (a voltage across the resistor R10) of a level corresponding to the input current Is is output from the output circuit 22.
Vo is output.

On the other hand, when the second switching element Q2 is turned on, one end of the detection resistor Rs is connected to the reference point (ground) via the second switching element Q2. Diode D
Since the input current Is flows into the resistor R10 via the resistor 14, the output circuit 22 outputs a detection voltage Vo having a level corresponding to the input current Is.

Then, a detection voltage Vo during the ON period of the first switching element Q1 and a detection voltage Vo during the ON period of the second switching element Q2 are synchronized with the control signals S1 and S2 by an on / off control unit (not shown). By comparing the on-periods of the first to fourth switching elements Q1 to Q4 so that the two types of detection voltages Vo become equal, the input current Is depending on the polarity of the AC power supply Vs is obtained.
And the DC component and the even harmonic component of the input current Is can be suppressed.

As described above, in the present embodiment, the ninth embodiment is used.
As compared with the above, there is an advantage that the circuit configuration can be simplified and the cost can be reduced, and the even harmonic component of the input current Is can be suppressed stably.

(Twelfth Embodiment) FIG. 20 is a circuit diagram of a twelfth embodiment. In this embodiment, a first chopper operation is performed.
A current detection circuit 23 for detecting a current (input current Is) flowing through the second switching elements Q1 and Q2,
Comparing means for comparing the two detection values of the current detection circuit 23, wherein a DC component and an even harmonic component contained in the input current Is from the AC power supply Vs are suppressed in accordance with the comparison result of the comparing means. First, the first to fourth switch elements are turned on and off.

The specific circuit configuration of the current detection circuit 23 is shown in FIG.
Shown in A detection resistor Rs is inserted between the source of the second switching element Q2 and the anode of the diode D6. Output resistors Ro are connected in common between the output terminals of the first and second output circuits 24 and 25 in parallel.

The first output circuit 24 includes a transistor Q21
Q23, a control power supply Vcc, a resistor for bias, diodes D16 and D17, a capacitor C21, and the like. A current having a level corresponding to the voltage between both ends of the detection resistor Rs is caused to flow through the output resistor Ro, so that the input current Is It outputs a corresponding detection voltage Vo. The second output circuit 25 includes transistors Q24 to Q27, a control power supply Vcc, a resistor for bias, diodes D18 and D19, a capacitor C22 and the like, and outputs a current having a level corresponding to the voltage across the detection resistor Rs. And outputs a detection voltage Vo corresponding to the input current Is by flowing the current through the resistor Ro.

Next, the operation of the current detection circuit 23 will be described.
First, when the second switching element Q2 is turned on, a portion Is1 of the input current Is flows downward through the detection resistor Rs in FIG. 21 to cause a voltage drop. This voltage drop causes the transistor Q24 in the second output circuit 25 to turn on. The bias voltage increases. As a result, the transistor Q24 is turned on and the transistor Q25 is turned off. The transistor Q26 is turned on and the transistor Q27 is turned off while the electric charge is stored in the capacitor C22 via the resistor R48. The current flowing through the resistor Ro increases. That is, the detection voltage Vo having a level corresponding to the input current Is is output between both ends of the resistor Ro.

Conversely, when the first switching element Q1 is turned on, a part Is1 of the input current Is flows in the opposite direction (upward in FIG. 21) to the detection resistor Rs, causing a voltage drop.
Due to this voltage drop, the bias voltage of the transistor Q21 in the first output circuit 24 decreases. As a result, the transistor Q21 is turned off, and the electric charge is stored in the capacitor C21 via the resistor R26.
Is turned on and the transistor Q23 is turned off, and the current flowing through the output resistor Ro via the diode D16 increases. That is, the input current Is is applied between both ends of the resistor Ro.
Is output at a level corresponding to.

Here, an on / off control unit (not shown)
The detection voltage Vo during the on-period of the first switching element Q1 is compared with the detection voltage Vo during the on-period of the second switching element Q2 in synchronization with the control signals S1 and S2, and for example, the on-state of the first switching element Q1 is turned on. If the detection voltage Vo in the period is higher than the detection voltage Vo in the ON period of the second switching element Q2, the on-duty of the control signals S1 and S4 is reduced to make the first and fourth control signals S1 and S4 smaller.
By shortening the on-periods of the switching elements Q1 and Q4 and increasing the on-duty of the control signals S2 and S3 to prolong the on-periods of the second and third switching elements Q2 and Q3, the above two types of detection can be performed. The first to fourth switching elements Q1 to Q4 are set so that the voltages Vo are equal.
The ON period of Q4 is controlled. Thus, the variation of the input current Is due to the polarity of the AC power supply Vs is reduced, and the DC component and even-order harmonic components of the input current Is can be suppressed.

(Thirteenth Embodiment) FIG. 22 is a circuit diagram of a thirteenth embodiment. In this embodiment, a first chopper operation is performed.
First and second current detection circuits 26 and 27 for detecting currents (input current Is) flowing through the first and second switching elements Q1 and Q2, respectively, and the first and second current detection circuits 2
And a comparing means for comparing the respective detected values of the DC power and the even-order harmonic components contained in the input current Is from the AC power supply Vs according to the comparison result of the comparing means. In this manner, the first to fourth switch elements are turned on and off.

The first current detection circuit 26 connects the detection resistor Rs1 inserted between the source of the first switching element Q1 and the AC power supply Vs to the first switching element Q1 of the detection resistor Rs1. A diode Ds1 having an anode connected to a point, and a capacitor Cs1 having a high potential (plus) side connected to the cathode of the diode Ds1 and a low potential side connected to the AC power supply Vs in parallel with the detection resistor Rs1.
The detection voltage Vc1 corresponding to the current flowing through the first switching element Q1 is output across the capacitor Cs1. Further, the second current detection circuit 27 includes a connection point between a detection resistor Rs2 inserted between the drain of the second switching element Q2 and the AC power supply Vs, and the second switching element Q2 of the detection resistor Rs2. A diode Ds2 having a cathode connected to the diode Ds2 and a capacitor C having a low potential side connected to the anode of the diode Ds2 and a high potential side connected to the AC power supply Vs in parallel with the detection resistor Rs2.
s2, and outputs a detection voltage Vc2 corresponding to the current flowing through the second switching element Q2 across the capacitor Cs2.

The comparing means 28 includes a second current detecting circuit 27
The first and second capacitors are based on the low potential side of the capacitor Cs2.
The voltage obtained by adding the detection voltages Vc1 and Vc2 of the current detection circuits 26 and 27 (= Vc1 + Vc2) and the detection voltage Vc2 of the second current detection circuit 27 are doubled by the voltage doubler 29 (= 2 ×
A voltage Vz (= Vx + E) obtained by superimposing a DC voltage E on a difference voltage Vx (= Vc1 + Vc2−2 × Vc2) from the voltage Vc2) is compared with the sawtooth voltage output from the sawtooth generator 3 by the comparator CP5. Is output to the switch control circuit 30 as a square wave signal corresponding to the magnitude relationship of the above and a signal obtained by inverting the signal by the inverter 5. The switch control circuit 30 generates control signals S1 and S4 for turning on and off the first and fourth switching elements Q1 and Q4 in response to an input signal from the comparing means 28, and switches the second and third switching elements Q2 and Q3. It outputs control signals S2 and S3 to be turned on and off.

For example, if the amount of current flowing per unit time in the first and second switching elements Q1 and Q2 is the same, the capacitor Cs1 in the first current detection circuit 26
Is higher than the potential on the high potential side of the capacitor Cs2 in the second current detection circuit 27, the voltage Vx becomes zero, and the input voltage on the inversion side of the comparator CP5 in the comparison means 28 becomes DC. Voltage (reference voltage) E
Becomes At this time, the level of the reference voltage E is set so that the on-duty ratio of the output signal of the comparator CP5 becomes 50%. Then, when the current flowing through the second switching element Q2 becomes larger than the current flowing through the first switching element Q1, the voltage Vz (Vx <0) is input to the inverting side of the comparator CP5. On-duty ratio of output signal is 50
%. As a result, the switch control circuit 30 outputs the control signals S1 and S4 to prolong the on-period of the first and fourth switching elements Q1 and Q4, and outputs the control signals S1 and S4 while the on-period of the second and third switching elements Q2 and Q3. Output the control signals S2 and S3 to shorten the first and fourth switching elements Q1 and Q4.
And the second and third switching elements Q2, Q2
3 and the ON period of the AC power supply Vs is equalized, and control is performed so that the amount of input current Is drawn in each half cycle of the power supply cycle of the AC power supply Vs is the same.

As described above, in the present embodiment, the AC power supply V
s of the AC power supply Vs by directly detecting the fluctuation of the input current Is caused by the fluctuation of the power supply voltage of the AC power supply Vs by feed-forward controlling the on-periods of the first and second switching elements Q1 and Q2 that operate the chopper. , The amount of input current Is drawn in each half cycle is the same, and even-order harmonic components of the input current generated by power supply fluctuations and the like can be suppressed.

(Embodiment 14) FIG. 23 shows a circuit diagram of Embodiment 14. In the present embodiment, first and second current detection circuits 31 and 32 for detecting currents (input current Is) flowing through diodes D5 and D6 constituting a chopper circuit, respectively.
And comparing means 28 for comparing the respective detected values of the first and second current detecting circuits 31 and 32 with each other.
The first to fourth switch elements are turned on and off so as to suppress the DC component and the even-order harmonic component included in the input current Is from the AC power supply Vs in accordance with the comparison result. However, since the configuration and operation of the comparison means 28 and the switch control circuit 30 except for the first and second current detection circuits 31 and 32 are common to those of the thirteenth embodiment, the common parts are denoted by the same reference numerals. Is omitted.

The first current detection circuit 31 includes a detection resistor Rs3 inserted between the first reactor L1 and the anode of the diode D5, and a diode D5 of the detection resistor Rs3.
A diode Ds3 having a cathode connected to a connection point with the anode thereof, and a capacitor Cs3 having a low potential side connected to the anode of the diode Ds3 and a high potential side connected to the first reactor L1 in parallel with the detection resistor Rs3. And a detection voltage V corresponding to the current flowing through the diode D5.
c3 is output between both ends of the capacitor Cs3. Further, the second current detection circuit 32 is connected to the first reactor L1
A detection resistor Rs4 inserted between the detection resistor Rs4 and the cathode of the diode D6, and a diode Ds4 having an anode connected to a connection point between the detection resistor Rs4 and the cathode of the diode D6.
And a capacitor Cs4 having a high potential side connected to the cathode of the diode Ds4 and a low potential side connected to the first reactor L1 in parallel with the detection resistor Rs4.
The detection voltage Vc4 corresponding to the current flowing through the diode D6 is output between both ends of the capacitor Cs4.

The comparing means 28 uses the low potential side of the capacitor Cs3 of the first current detection circuit 31 as a reference and detects the detection voltages Vc3, Vc3 of the first and second current detection circuits 31, 32.
The difference voltage Vx (= Vc3 + Vc4−2 ×) between the voltage obtained by adding Vc4 (= Vc3 + Vc4) and the voltage (= 2 × Vc3) obtained by doubling the detection voltage Vc3 of the first current detection circuit 31 by the voltage doubler circuit 29.
Vc3) is a voltage Vz (= Vx + E) obtained by superimposing a DC voltage E on the Vc3).
Is compared with the sawtooth voltage output from the sawtooth wave generator 3 by the comparator CP5, and a square wave signal corresponding to the magnitude relationship between the two and a signal obtained by inverting the signal by the inverter 5 are output to the switch control circuit 30. I do.

For example, when the current flowing through the second switching element Q2 is larger than the current flowing through the first switching element Q1, the voltage Vz (Vx <0) is input to the inverting side of the comparator CP5. The on-duty ratio of the output signal of the comparator CP5 becomes higher than 50%. As a result, the switch control circuit 30 outputs the control signals S1 and S4 to prolong the on-period of the first and fourth switching elements Q1 and Q4, and outputs the control signals S1 and S4 while prolonging the on-period of the second and third switching elements Q2 and Q3. By outputting the control signals S2 and S3 that shorten the
The on-periods of the first and fourth switching elements Q1 and Q4 are equal to the on-periods of the second and third switching elements Q2 and Q3, and the input current Is is drawn in each half of the power supply cycle of the AC power supply Vs. Control the amount to be the same.

Thus, as in the thirteenth embodiment, the on-periods of the first and second switching elements Q1 and Q2 that perform the chopper operation are controlled, and the input current Is in each half cycle of the power supply cycle of the AC power supply Vs is controlled. By making the amount of pull-in the same, it is possible to suppress even-order harmonic components of the input current generated by power supply fluctuations and the like.

(Fifteenth Embodiment) FIG. 24 is a circuit diagram of a fifteenth embodiment. This embodiment includes first and second current peak value detection circuits PK1 and PK2 for detecting a peak value of a current flowing through an inductor L2 of a load circuit Z, and first and second current peak value detection circuits PK1 and PK2.
And a comparator CP6 for comparing the detection values of the current peak value detection circuits PK1 and PK2 with each other. The control signals S1 to S4 for turning on and off the first to fourth switching elements Q1 to Q4 are generated and output so that the ON periods of the second and third switching elements Q2 and Q3 are equal. Since other configurations and basic operations are the same as those of the first and second embodiments, common portions are denoted by the same reference numerals and description thereof is omitted.

One end of a secondary winding n2 for current detection provided in the inductor L2 is connected to the ground, and the other end is connected to the ground via a diode Dx and a parallel circuit of a resistor Rx and a capacitor Cx. . The first peak value detection circuit PK1 holds the peak value of the voltage Vcx across the capacitor Cx with a time constant that is several times longer than the power supply frequency of the AC power supply Vs, and holds one cycle of the power supply cycle of the AC power supply Vs. Outputs a first detection voltage Vc corresponding to the peak current of the current flowing through the inductor L2. Also, the second
The peak value detection circuit PK2 holds the peak value of the voltage Vcx across the capacitor Cx with a time constant much shorter than the power supply cycle of the AC power supply Vs and several times longer than the cycle of the high-frequency output current. , And outputs a second detection voltage Vd corresponding to the envelope of the current flowing through the inductor L2.

By the way, as shown in FIG.
When the input current Is is biased in accordance with the polarity of s, the voltage Vc1 across the smoothing capacitor C1 and the current IL2 flowing in the inductor _L2 are also biased in accordance with the polarity of the AC power supply Vs, and the first peak value A detection voltage Vc of the detection circuit PK1,
The detection voltage Vd of the second peak value detection circuit PK2 is different from the detection voltage Vd at an arbitrary polarity of the AC power supply Vs. Conversely, if the peak value of the voltage Vcx is constant regardless of the polarity of the AC power supply Vs, the first and second detection voltages Vc and Vd become equal.

Therefore, according to the magnitude relationship between the first and second detection voltages Vc and Vd compared by the comparator CP6, the control circuit 7 causes the first and fourth switching elements Q
The control signals S1 to S4 are generated and output such that the on-periods of the first and Q4 are made longer or shorter and the on-periods of the second and third switching elements Q2 and Q3 are made shorter or longer. That is, the control circuit 7 generates control signals S1 to S4 for controlling on / off of the first to fourth switching elements Q1 to Q4 so that the first detection voltage Vc and the second detection voltage Vd become equal. Since the output is performed, the bias of the input current Is according to the polarity of the AC power supply Vs is eliminated, and the input current Is does not include a DC component and an even-order harmonic component.

As described in the fifth embodiment, the configuration may be such that the voltage Vcx is switched and input to the first and second peak value detection circuits PK1 and PK2 according to the polarity of the AC power supply Vs.

(Embodiment 16) FIG. 26 is a block diagram of a main part of Embodiment 16. This embodiment is different from the configuration of the twelfth embodiment in that a zero-cross detector 33 for detecting a zero-cross of the power supply voltage of the AC power supply Vs and a zero-cross detector 3
3, a sine wave generator 34 that generates a sine wave voltage synchronized with the power supply voltage of the AC power supply Vs, a detection voltage Vo of the current detection circuit 23, and a sine wave output from the sine wave generator 34. A comparison unit 35 for comparing and outputting a detection voltage Vo corresponding to the polarity of the AC power supply Vs is provided. Other configurations and basic operations are common to those in the twelfth embodiment, so that illustration and description are omitted.

The zero-crossing detector 33 calculates the average value of the current flowing through the detection resistor Rs, and detects the zero-crossing of the power supply voltage of the AC power supply Vs from the time when the calculated average value decreases most. The sine wave generator 34
Is composed of an oscillator that outputs a sine wave voltage in synchronization with the zero-cross detection signal from the zero-cross detection unit 33.

Here, an on / off control unit (not shown)
The detection voltage Vo during the on-period of the first switching element Q1 is compared with the detection voltage Vo during the on-period of the second switching element Q2 in synchronization with the control signals S1 and S2, and for example, the on-state of the first switching element Q1 is turned on. If the detection voltage Vo in the period is higher than the detection voltage Vo in the ON period of the second switching element Q2, the on-duty of the control signals S1 and S4 is reduced to make the first and fourth control signals S1 and S4 smaller.
By shortening the on-periods of the switching elements Q1 and Q4 and increasing the on-duty of the control signals S2 and S3 to prolong the on-periods of the second and third switching elements Q2 and Q3, the above two types of detection can be performed. The first to fourth switching elements Q1 to Q4 are set so that the voltages Vo are equal.
The ON period of Q4 is controlled. Thus, the variation of the input current Is due to the polarity of the AC power supply Vs is reduced, and the DC component and even-order harmonic components of the input current Is can be suppressed. Furthermore, in the present embodiment, the sine wave voltage output from the sine wave generation unit 34 and the detection voltage Vo are compared in a timely manner in the comparison unit 35, and the input current Is can be formed into a sine wave regardless of the input voltage waveform. Even harmonic components can be further suppressed.

(Embodiment 17) FIG. 27 is a circuit diagram of an embodiment 17. Since the circuit configuration of this embodiment is the same as that of the first embodiment, the common parts are denoted by the same reference numerals and description thereof will be omitted. In the first embodiment, the on / off control unit 1 controls the first and fourth switching elements Q in accordance with the detection voltages Vk and Vj of the first and second average value detection means 10 and 11.
1, the ON period of Q4 and the ON periods of the second and third switching elements Q2, Q3 are controlled. In the present embodiment, the first and fourth switching elements Q1 are controlled in accordance with the detection voltages Vk, Vj. , Q4 and the second and third switching elements Q2, Q3 are turned on per unit time.

FIG. 28 shows an operation waveform diagram in the present embodiment. For example, when the ON period of the first switching element Q1 is shorter than the ON period of the second switching element Q2, the second detection voltage Vj is lower than 0.5 times the first detection voltage Vk. . Therefore, the on / off control unit 1 '
In such a case, the control signal S2 of the second switching element Q2 is decimated and output to control the second switching element Q2 to perform a chopper operation to reduce the input current Is taken in. as a result,
The input current Is has a positive / negative waveform, and the DC component and the even harmonic components included in the input current Is can be suppressed as in the first embodiment.

According to the present embodiment, the first to fourth
DC components and even-order harmonic components contained in the input current can be suppressed without changing the ON periods of the switching elements Q1 to Q4.

[0127]

According to the first aspect of the present invention, there is provided a series circuit of first and second switch elements which does not block current in the reverse direction, and a series circuit of third and fourth switch elements which does not block current in the reverse direction. A smoothing capacitor in which these two series circuits are connected in parallel between both ends; a series circuit of two diodes connected in anti-parallel between both ends of the smoothing capacitor;
An AC power supply having one end connected to a connection point of the second switch element and a first reactor inserted between the other end of the AC power supply and a connection point of the two diodes; And a load circuit inserted between the connection point of the third switch element and the connection point of the third and fourth switch elements, wherein the first and second switch elements are operated at a frequency higher than the power supply frequency of the AC power supply. A power supply device that alternately turns on and off, and turns on and off the third and fourth switch elements in synchronization with the second and first switch elements located at diagonal sides to supply high-frequency power to a load circuit, The control means for feedback-controlling the ON / OFF of the first to fourth switch elements so as to suppress the DC component and the even-order harmonic components included in the input current from the AC power supply increases cost. There is an effect that it is possible to suppress the DC component and even harmonic components in the input current from the AC power source without and complicated adjustment without causing.

According to a second aspect of the present invention, the control means detects the average value of the voltage between both ends of the smoothing capacitor and the average value of the voltage between both ends of the second switch element on the low potential side. Average value detecting means for detecting the second average value, and when the second average value detected by the second average value detecting means is larger than approximately half of the first average value detected by the first average value detecting means The length of the ON period of the second switch element with respect to the sum of the ON periods of the first switch element and the second switch element is increased, and the second average value is smaller than approximately half of the first average value. Includes on / off control means for turning on / off the first to fourth switch elements so as to lengthen the on time of the first switch element with respect to the sum of the respective on periods of the first switch element and the second switch element. Therefore, the effect of the invention of claim 1 Ete, there is an effect that it is possible to suppress the DC component and even order harmonic components included without detecting the input current to the input current from the AC power source.

According to a third aspect of the present invention, the control means detects the average value of the voltage between both ends of the second switch element on the low potential side, and the fourth switch on the low potential side. A second average value detecting means for detecting an average value of the voltage between both ends of the element, and a second average value wherein the first average value detected by the first average value detecting means is detected by the second average value detecting means. If it is larger than the value, the ON period of the second switch element is lengthened and the ON period of the fourth switch element is shortened. If the first average value is smaller than the second average value, the second An on-off control unit for turning on and off the first to fourth switch elements so as to shorten the on-period of the switch element and lengthen the on-period of the fourth switch element is provided. In addition, the DC component and even-order high There is an effect that it is possible to suppress the wave component.

According to a fourth aspect of the present invention, the control means includes a first average value detecting means for obtaining an average value of a potential difference between a connection point between the high potential side of the smoothing capacitor and the first reactor of the AC power supply. A second average value detecting means for obtaining an average value of a potential difference between a low potential side of the smoothing capacitor and a connection point between the first reactor of the AC power supply and a first average value detected by the first average value detecting means. Is larger than the second average value detected by the second average value detecting means, the on-period of the first switch element is shortened and the on-period of the second switch element is lengthened to increase the first. Is smaller than the second average value, the first to fourth switch elements are turned on and off so as to increase the on-period of the first switch element and shorten the on-period of the second switch element. On-off control means , In addition to the effect of the invention of claim 1,
There is an effect that a DC component and an even-order harmonic component can be suppressed with a simple circuit configuration.

According to a fifth aspect of the present invention, the control means includes a first and a second peak value detecting means for detecting a peak value of a voltage across the smoothing capacitor and a voltage between both ends of the smoothing capacitor according to the polarity of the AC power supply. Switching means for switching to and inputting to the first and second peak value detecting means; and comparing means for comparing the detection values of the first and second peak value detecting means with each other. The first to fourth switch elements are turned on and off so as to suppress the DC component and the even-order harmonic components included in the input current from the AC power supply. The configuration has an effect that a DC component and an even-order harmonic component can be suppressed.

[0132] The invention according to claim 6 is the first inductor, one end of which is connected to a connection point of the first and second switch elements.
A load circuit comprising a parallel circuit of a second inductor having one end connected to a connection point of the third and fourth switch elements, a discharge lamp connected between the other ends of the first and second inductors, and a resonance capacitor; The control means comprises: first voltage detection means for detecting a voltage at a connection point between the first inductor and the discharge lamp; and a second voltage detection means for detecting a voltage at a connection point between the second inductor and the discharge lamp. And a first to a fourth such that the DC component and the even-order harmonic component contained in the input current from the AC power supply are suppressed in accordance with the detection values of the first and second voltage detecting means. Is turned on and off, the DC component and the even-order harmonic components contained in the input current from the AC power supply can be suppressed without detecting the input current in addition to the effect of the first aspect. This has the effect.

According to a seventh aspect of the present invention, the control means detects the average value of the current flowing through the first reactor according to the polarity of the AC power supply, the first and second current average value detection means,
And a comparing means for comparing the detection values of the second current average value detecting means with each other, and suppressing a DC component and an even-order harmonic component contained in the input current from the AC power supply according to the comparison result of the comparing means. Since the first to fourth switch elements are turned on and off as described above, the same effect as the first aspect of the invention can be obtained.

According to an eighth aspect of the present invention, the control means includes a first and a second current peak value detecting means for detecting a peak value of a charging current for charging the smoothing capacitor, and a control circuit for controlling the smoothing capacitor according to the polarity of the AC power supply. Switching means for switching and inputting the voltage between both ends to the first and second current peak value detecting means;
And a comparison means for comparing the detection values of the second current peak value detection means with each other, and suppresses a DC component and an even-order harmonic component contained in the input current from the AC power supply according to the comparison result of the comparison means. Since the first to fourth switch elements are turned on and off as described above, the same effect as the first aspect of the invention can be obtained.

According to a ninth aspect of the present invention, the control means detects first and second current detection means for detecting currents flowing through the first and second switch elements, respectively, and the first and second current detection means. And a first to fourth switch for suppressing a DC component and an even-order harmonic component contained in an input current from an AC power supply according to a comparison result of the comparison unit. Since the elements are turned on and off, in addition to the effect of the first aspect, the input current fluctuation due to the power supply voltage fluctuation of the AC power supply is detected from the current flowing through the first and second switch elements, and the first to fourth elements are detected. By performing feedforward control of the switch element, there is an effect that a DC component and an even harmonic component included in the input current can be suppressed.

A load circuit is constituted by a discharge lamp, a capacitor connected in parallel to the discharge lamp, and an inductor connected in series with the discharge lamp to form a resonance circuit with the capacitor. First and second peak value detecting means for detecting the peak value of the current flowing through the inductor of the load circuit in accordance with the polarity of the first and second peak value detecting means, and comparing means for comparing the detected values of the first and second peak value detecting means with each other. Wherein the first to fourth switch elements are turned on / off so as to suppress a DC component and an even-order harmonic component included in the input current from the AC power supply in accordance with the comparison result of the comparing means. The same effect as that of the first invention is exerted.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment.

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is an operation explanatory view of the above.

FIG. 4 is a circuit diagram of a second embodiment.

FIG. 5 is a circuit diagram of a third embodiment.

FIG. 6 is a circuit diagram of a fourth embodiment.

FIG. 7 is a circuit diagram of a fifth embodiment.

FIG. 8 is an operation explanatory view of the above.

FIG. 9 is a circuit diagram of a sixth embodiment.

FIG. 10 is an operation explanatory view of the above.

FIG. 11 is an operation explanatory diagram of the above.

FIG. 12 is a circuit diagram of a seventh embodiment.

FIG. 13 is a circuit diagram of another configuration of the above.

FIG. 14 is a circuit diagram of an eighth embodiment.

FIG. 15 is an explanatory diagram of the operation of the above.

FIG. 16 is a circuit diagram of a ninth embodiment.

FIG. 17 is a circuit diagram of a current detection circuit in Embodiment 1;

FIG. 18 is a circuit diagram of a current detection circuit according to the tenth embodiment.

FIG. 19 is a circuit diagram of a current detection circuit according to the eleventh embodiment.

FIG. 20 is a circuit diagram of a twelfth embodiment.

FIG. 21 is a circuit diagram of a current detection circuit in the above.

FIG. 22 is a circuit diagram of a thirteenth embodiment.

FIG. 23 is a circuit diagram of a fourteenth embodiment.

FIG. 24 is a circuit diagram of a fifteenth embodiment.

FIG. 25 is an explanatory diagram of the operation of the above.

FIG. 26 is a main part circuit block diagram in a sixteenth embodiment.

FIG. 27 is a circuit diagram of a seventeenth embodiment.

FIG. 28 is an explanatory diagram of the operation of the above.

FIG. 29 is a circuit diagram of Conventional Example 1.

FIG. 30 is an explanatory diagram of the operation of the above.

FIG. 31 is an explanatory diagram of the above operation.

FIG. 32 is a circuit diagram of a second conventional example.

FIG. 33 is an explanatory diagram of the operation of the above.

FIG. 34 is a circuit diagram of a third conventional example.

FIG. 35 is an explanatory diagram of the operation of the above.

FIG. 36 is an explanatory diagram of the above operation.

FIG. 37 is an explanatory diagram of the operation of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 On-off control part 10 1st average value detection means 11 2nd average value detection means Q1-Q4 Switching element D1-D6 Diode L1 1st reactor C1 Smoothing capacitor Vs AC power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Onishi 1048 Odakadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. 72) Inventor Masahiro Naroo 1048 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Works Co., Ltd. DB01 DC02 DC05 EA13

Claims (10)

[Claims] 1. A first and a second circuit which do not block a reverse current.
And a series circuit of third and fourth switch elements that do not block current in the reverse direction.
Two series circuits are connected in parallel between both ends, and two series circuits are connected in anti-parallel between both ends of the smoothing capacitor.
A series circuit of two diodes, an AC power supply having one end connected to a connection point of the first and second switch elements, and a first power supply inserted between the other end of the AC power supply and the connection point of the two diodes. , And a load circuit inserted between the connection point of the first and second switch elements and the connection point of the third and fourth switch elements. The power supply is turned on and off alternately at a frequency higher than the power supply frequency of the power supply, and the third and fourth switch elements are turned on and off in synchronization with the second and first switch elements located at diagonal sides, respectively, to provide a load circuit. In a power supply device for supplying high-frequency power, feedback control is performed on / off of first to fourth switch elements so as to suppress a DC component and an even-order harmonic component included in an input current from an AC power supply. Power supply, characterized in that it comprises means. 2. The control means includes: first average value detection means for detecting an average value of the voltage between both ends of the smoothing capacitor; and second control means for detecting an average value of the voltage between both ends of the second switch element on the low potential side. And if the second average value detected by the second average value detection means is larger than approximately half of the first average value detected by the first average value detection means, The ON period of the second switch element with respect to the sum of the ON periods of the switch element and the second switch element is increased, and the second
Is smaller than substantially half of the first average value, the ON period of the first switch element is made longer with respect to the sum of the ON periods of the first switch element and the second switch element. 2. The power supply device according to claim 1, further comprising an on / off control unit for turning on / off the first to fourth switch elements. 3. The control means includes: first average value detection means for detecting an average value of a voltage between both ends of a second switch element on a low potential side; and a voltage between both ends of a fourth switch element on a low potential side. A second average value detecting means for detecting the average value of the first average value, and a case where the first average value detected by the first average value detecting means is larger than the second average value detected by the second average value detecting means Has a second
, The ON period of the fourth switch element is shortened, and the ON period of the fourth switch element is shortened. When the first average value is smaller than the second average value, the ON period of the second switch element is shortened. 2. The power supply device according to claim 1, further comprising: on / off control means for turning on / off the first to fourth switch elements so as to lengthen the ON period of the fourth switch element. 4. The control means includes: first average value detection means for obtaining an average value of a potential difference between a high potential side of the smoothing capacitor and a connection point between the first reactor of the AC power supply; A second average value detecting means for calculating an average value of a potential difference between a potential side and a connection point between the AC power supply and the first reactor; and a first average value detected by the first average value detecting means is a second average value. If the average value is larger than the second average value detected by the second average value detection means, the ON period of the first switch element is shortened and the ON period of the second switch element is increased to increase the first switch element.
Is smaller than the second average value, the first to fourth switch elements are turned on and off so as to increase the on-period of the first switch element and shorten the on-period of the second switch element. The power supply device according to claim 1, further comprising an on / off control unit that performs the operation. 5. The control means includes: first and second peak value detecting means for detecting a peak value of a voltage across the smoothing capacitor; and a first and second peak value detecting means for detecting a voltage across the smoothing capacitor according to the polarity of the AC power supply. Switching means for switching and inputting to the peak value detecting means, and comparing means for comparing the detection values of the first and second peak value detecting means with each other. The first to fourth components are controlled so as to suppress the DC component and even-order harmonic components contained in the input current.
The power supply device according to claim 1, wherein the switch element is turned on and off. 6. A first inductor having one end connected to a connection point between the first and second switch elements, a second inductor having one end connected to a connection point between the third and fourth switch elements, A load circuit is formed by a parallel circuit of a discharge lamp and a resonance capacitor connected between the other ends of the first and second inductors, and the control means detects a voltage at a connection point between the first inductor and the discharge lamp. And a second voltage detecting means for detecting a voltage at a connection point between the second inductor and the discharge lamp. The first voltage detecting means detects a voltage at a connection point between the second inductor and the discharge lamp. 2. The switch element according to claim 1, wherein the first to fourth switch elements are turned on and off so as to suppress a DC component and an even-order harmonic component contained in an input current from the AC power supply.
The power supply as described. 7. The first and second current average value detecting means for detecting an average value of the current flowing through the first reactor according to the polarity of the AC power supply, and the first and second current average value detecting means. A comparison means for comparing the detection values of the value detection means with each other, wherein first to first and second even harmonic components are suppressed according to the comparison result of the comparison means. The power supply device according to claim 1, wherein the fourth switch element is turned on / off. 8. The control means includes: first and second current peak value detecting means for detecting a peak value of a charging current for charging the smoothing capacitor; and a first and second current peak value detecting means for detecting a voltage across the smoothing capacitor according to a polarity of the AC power supply. Switching means for switching and inputting to the second current peak value detecting means, and comparing means for comparing the detection values of the first and second current peak value detecting means with each other, according to the comparison result of the comparing means. 2. The power supply device according to claim 1, wherein the first to fourth switch elements are turned on and off so as to suppress a DC component and an even-order harmonic component included in the input current from the AC power supply. 9. The control means compares the detected values of the first and second current detecting means with the first and second current detecting means for detecting the current flowing through the first and second switch elements, respectively. And turning on and off the first to fourth switch elements so as to suppress the DC component and the even-order harmonic component included in the input current from the AC power supply according to the comparison result of the comparison unit. The power supply device according to claim 1, wherein: 10. A load circuit is constituted by a discharge lamp, a capacitor connected in parallel to the discharge lamp, and an inductor connected in series to the discharge lamp to form a resonance circuit with the capacitor. A first and a second peak value detecting means for respectively detecting a peak value of a current flowing through the inductor of the load circuit; and a comparing means for comparing detection values of the first and the second peak value detecting means, According to a comparison result of the comparing means, a first component is controlled so as to suppress a DC component and an even harmonic component included in the input current from the AC power supply.
The power supply device according to claim 1, wherein the first to fourth switch elements are turned on and off.