JP3054954B2 - Condenser AC boost circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformerless AC booster, and more particularly to a lightweight, small-sized capacitor AC booster with less noise.

[Conventional technology]

2. Description of the Related Art Conventionally, a so-called electronic transformer that boosts an alternating current by using a capacitor and a switching element to alternately switch a capacitor in series, parallel, or the like has been known.

[Problems to be solved by the invention]

However, there is a problem that the switching frequency must be higher than the frequency of the input AC power supply, thereby causing noise.

An object of the present invention is to solve this problem, and also to provide a lightweight and compact condenser AC booster.

[Means for solving the problem]

In order to achieve the above object, a capacitor AC booster circuit according to the present invention has an input AC power supply (AC) as shown in FIGS. 1 to 3 and FIG. 5 to FIG. Two capacitors (C1, C2) are connected in parallel to one terminal of the, and two sets of rectifier circuits are connected in parallel to the other terminal of the input AC power supply (AC) so that their output polarities are opposite to each other. The two capacitors (C1, C2) are connected so that their rectified voltages are charged to opposite polarities, and the positive output terminal of one capacitor (C1) is connected to the load (Z
L), a switching element (T1) that is turned on for only the positive half cycle of the input AC power supply is connected in series between one terminal of the input AC power supply, and the negative output terminal of the other capacitor (C2) and the load (Z
A switching element (T2) that is turned on for only the negative half cycle of the input AC power supply is connected in series between one terminal of L) and the other terminal of the load (ZL) is the other terminal of the input AC power supply. And a drive circuit for individually driving the switching elements (T1, T2) on and off in accordance with the cycle of the input AC power supply (AC), whereby the positive and negative sides of the input AC power supply are provided at both ends of the load (ZL). A positive voltage in which the positive voltage charged in the one capacitor (C1) is superimposed on a voltage, and a negative voltage in which the negative voltage charged in the other capacitor (C2) is superimposed on the negative voltage of the input AC power supply. Characterized in that it is configured to output an AC voltage formed from

As the rectifier circuit, for example, as shown in FIG.
A half-wave rectifier circuit using rectifier diodes (D1, D2) can be used.

Further, as shown in FIG. 2, a capacitor step-down DC power supply circuit or a switching DC power supply circuit (S1, S2) can be used.

Furthermore, as shown in FIG. 3, a capacitor step-down DC power supply circuit or a switching DC power supply circuit (S1, S2)
And a half-waveform voltage doubler rectifier (D3, D5, C3, C5) (D4, D6, C
4, C6) may be used in combination.

Also, a half-waveform voltage doubler rectifier circuit (D3, D5, C3, C5) (D4,
D6, C4, C6) alone.

Alternatively, in the present invention, two capacitors (C1, C2) are connected in parallel to one terminal of an input AC power supply (AC) as shown in FIG. Then, two sets of switching full-waveform voltage doubler rectifiers (S1, S2) are connected in parallel to the other terminal of the input AC power supply (AC) so that their output polarities are opposite to each other. When the two capacitors (C1, C2) are charged to opposite polarities and the algebraic sum of the power supply (AC) voltage and the charged voltage of each capacitor (C1 or C2) reaches a predetermined voltage, they are charged. The circuit is configured to perform the switching operation of turning off the circuits individually, and two switching elements (T1, T4) that turn on only during the positive half cycle of the input AC power supply, and turn on only during the negative half cycle of the input AC power supply Two switching elements (T2, T3) ,
These four switching elements are connected alternately in the form of a bridge, and one end of the bridge is connected to the positive output terminal of one of the two capacitors (C1, C2), and the other end of the bridge. Is connected to the negative output terminal of the other capacitor (C2), and a load (ZL) is connected between the intermediate points of the bridge.

(Operation)

In the circuit example of FIG. 1, when the right terminal voltage of the input AC power supply AC is zero and the left terminal has a negative half cycle,
The rectifier diode D1 conducts, and the capacitor C1 is charged to approximately the peak value Vm of the input voltage. As described above, during the period when the input voltage is negative, the switching element T1 has its drive circuit (shown by a dotted line in the figure, details of which are shown in FIG. 5 and thereafter).
Is kept off by the action of. Therefore, even when the input voltage has passed the peak, the capacitor C1 holds the peak voltage Vm. Next, when the input voltage becomes a positive half cycle, the rectifier diode D1 does not conduct and the switching element
T1 is turned on by the drive circuit. At that time, the positive input voltage and the positive voltage charged in the capacitor C1 are added, and a positive voltage having a peak value of about 2 Vm is output to both ends of the load ZL.

The same operation principle is applied to the negative voltage, and the negative voltage charged in the capacitor C2 is superimposed on the negative input voltage to obtain a negative output voltage having a peak value of about −2 Vm.

The upper graph on the right side of FIG. 1 shows the input AC waveform of this circuit, and the lower graph shows the corresponding output voltage waveform across the load ZL.

The circuit example in FIG. 2 uses a capacitor step-down DC power supply circuit or switching DC power supply circuits S1 and S2 instead of the rectifier diodes D1 and D2 in FIG. During the negative half cycle of the input voltage, the capacitor C1 is charged to the output voltage Vn of the DC power supply circuit S1 through the DC power supply circuit S1.
Next, in the positive half cycle, the input voltage Vm and the voltage Vn of the capacitor C1 are superimposed, and about Vm +
A peak AC output voltage of Vn is obtained.

At this time, the capacitor C2 is charged to the voltage -Vn through the other capacitor step-down DC power supply circuit or the switching DC power supply circuit S2, and a peak AC output voltage of-(Vm + Vn) is obtained in the next negative half cycle. .

In the circuit example shown in FIG. 3, DC power supply circuits S1 and S2 having output voltages Vn and −Vn are used as in the case of FIG. 2, and a half of D3, D5, C3 and C5 is provided on the positive output side. A voltage multiplying rectifier circuit having a waveform is provided, and a half-waveform voltage multiplying rectifier circuit including D4, D6, C4, and C6 is similarly provided on the negative output side. The operation of this circuit is as follows. Immediately after startup, when the left terminal of AC has a negative half cycle, C1 is charged to Vn by the DC power supply circuit S1 (the right terminal of C1 is positive). During the next positive half cycle of AC, C3 is charged to Vm + Vn by the charging voltage of C1 and the voltage of AC (the upper terminal of C3 is positive). During the next negative half cycle of AC, the charging voltage of C1 and C3 and the voltage of AC
C5 is charged to 2Vm (the right terminal of C5 is positive).
Therefore, in the steady state, the switching element T1 conducts during the positive half cycle of AC, so that the load ZL has A
A voltage obtained by adding the voltages of C, C1, and C5, that is, a voltage having a peak of 3Vm + Vn, is output (see the lower right graph in FIG. 3).

In the circuit example of FIG. 4, the capacitor step-down DC power supply circuit or the switching DC power supply circuits S1 and S2 are used as full waveform voltage doubler rectifier circuits, the DC output voltage of which is approximately 2 Vn, and the four switching elements T1 to T4 are connected. A square-wave or sine-wave inverter is constructed by driving on / off with an input AC power supply or a signal source synchronized with the input AC power supply, whereby an output AC voltage of less than twice the input AC voltage is applied to both ends of the load ZL. It can be understood that 2Vn can be obtained (see the graph on the lower right side of FIG. 4).

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to specific embodiments shown in FIGS.

FIG. 5 is a circuit diagram showing an embodiment in which the present invention is configured as an AC voltage doubler. Such an AC voltage doubler is required when an electric product of a high-voltage power supply is taken to a low-voltage power supply country for use. The principle equivalent circuit is as shown in FIG. 1. Therefore, here, a drive circuit for performing on / off control of the switching elements T1 and T2 in the output stage and other circuit elements will be described.

In FIG. 5, D3, T3, R5, and R3 are switching elements T1.
And a circuit for driving the switching element T2 on and off with D4, T4, R6, and R4 (all shown by dotted lines in FIG. 1). R2 and C3 constitute a simple waveform improving circuit. R1 is a resistor for suppressing the inrush current. R1 or R2
By setting the value of appropriately, a sine wave with little distortion can be obtained. Further, by using a thermistor resistor for R1 and R2, heat loss at the time of large current output can be reduced. R9 and R10 are resistors for discharging the accumulated charge of the capacitor.

FIG. 6 shows an embodiment in which boosting is performed by using a compensation voltage obtained in a capacitor step-down DC power supply circuit, and a principle equivalent circuit thereof is as shown in FIG. is there. That is, in the circuit composed of C4, D1, and C1,
By taking out the divided voltage of C1, one simple capacitor step-down DC power supply circuit (corresponding to one specific example of S1 in FIG. 2) is formed, and another capacitor is similarly formed by a circuit composed of C4, D2, and C2. A step-down DC power supply circuit (corresponding to S2 in FIG. 2) is configured. These DC power circuits provide the compensation voltage. Its compensation voltage is C4 and C1 or C2
It is determined by the capacity ratio. It can be easily understood from the above description that an output voltage in which the compensation voltage is superimposed on the input AC voltage is obtained at both ends of the load ZL. Just C4
Is not suitable for high power because it must be a non-polar capacitor. Note that D3, T3, R5, R3, and D3
4, T4, R6, R4 are switching elements as in Fig.5
This is a drive circuit for T1 and T2.

The embodiment shown in FIG. 7 is also designed to perform boosting by using a compensation voltage, and its principle equivalent circuit is as shown in FIG. The power is supplied by a switching DC power supply circuit (corresponding to S1 and S2 in FIG. 2). A specific example of the switching DC power supply circuit will be described. In addition,
D3, T3, R5, and R3 are drive circuits for the switching element T1, as in the case of FIGS. 5 and 6.

Thus, the compensation voltage in the illustrated switching DC power supply circuit is substantially equal to the voltage charged in the capacitor C1 (or C2). Therefore, the voltage of C1 is monitored using a comparison circuit, and when this voltage exceeds a preset voltage, the switching element T5 is switched off by the output signal of the comparison circuit. That is, in the illustrated comparison circuit, when the voltage of C1 divided by R11 and W1 exceeds the threshold value (about 0.65 V) of the transistor T9, the switching element T5 is turned off through T9 and T7.

It should be noted that if the capacitance of C1 is not sufficient, the terminal polarity may be inverted. On the other hand, if the capacitance of C1 is too large, the terminal voltage of C1 may not be increased due to the internal resistance of the diode and the switching element.
This tendency increases as the compensation voltage decreases. In order to improve this, it is better to insert an inductance L1 as shown in the figure or to introduce a full-scale switching regulator circuit.

The embodiment of FIG. 8 is characterized in that an AC output voltage in a wide range from a voltage lower than the input power supply voltage to twice as large can be obtained. Therefore, the power supply device is useful when examining a change in characteristics from a power supply voltage fluctuation. The principle equivalent circuit is as shown in FIG. 4. Therefore, here, the switching full waveform voltage doubler rectifier circuit (corresponding to S1 and S2 in FIG. 4) and the output stage switching element (T1 to T
The specific configuration of the drive circuit of 4) will be described.

In FIG. 8, the configuration of the switching element T5 of the switching full-waveform voltage doubler rectifier circuit and the circuit for driving the same is almost the same as that of FIG. 7, but the configuration of the comparison circuit is slightly different. That is, in the case of FIG.
Monitors the algebraic sum with the voltage of C1 or C2, and when this exceeds the set voltage, issues an output signal and switches
T5 is turned off.

The comparing circuit of FIG. 8 is different from that of FIG. 7 in that an integrating circuit including a rectifier diode D11 and R15 and C5 is added. Since the integration time constant is large, the current flowing through R15 is always proportional to the input power supply voltage. Similarly, the current flowing through R11 is always proportional to the terminal voltage of C1. Since R11 and R15 are sufficiently larger than W1, the current flowing through W1 can be regarded as the sum of the above two currents. In other words,
The terminal voltage of W1 is proportional to the algebraic sum of the power supply voltage and the terminal voltage of C1. When this proportional voltage exceeds the threshold value of the transistor T9, T5 is turned off through T7. The configuration of the switching full waveform voltage doubler rectifier circuit S2 is the same as this.

Next, an on / off drive circuit for the switching elements T1 to T4 in the output stage will be described. The drive circuits for these four switching elements T1 to T4 are composed of four symmetric drive circuits. When the left terminal of the input AC power supply has a positive half cycle, a sine-wave or pseudo-sine-wave current having an appropriate width flows through a drive circuit including D7, R3, R5, R7, and T11, thereby turning on T1. Driven. Similarly, T4 is also driven on by a current flowing through a drive circuit including D10 and the like. However, T3 and T2 are turned off because the polarities of D9 and D8 with respect to the input AC power supply are opposite. Therefore, an output voltage of a certain polarity is obtained at the load ZL. Next, when the input AC power supply enters the negative half cycle, the switching element T3
T2 is driven on, and T1 and T4 are driven off. Therefore, an output voltage of the opposite polarity is obtained at the load ZL. Since the principle of operation in the negative half cycle is the same as that in the positive half cycle, the reference numerals of the respective circuit elements related to it are omitted in FIG.

〔The invention's effect〕

The capacitor AC booster according to the present invention having the above-described configuration has the following advantages. (1) Since the switching element in the output stage is driven by the input AC power supply or a signal source synchronized with the input AC power supply, noise reduction and efficiency improvement are achieved. (2) Since an electrolytic capacitor having a polarity can also be used, it is possible to achieve effects such as being lighter and smaller than a conventional transformerless AC booster circuit.

[Brief description of the drawings]

1 to 4 are circuit diagrams showing different typical basic modes of the capacitor AC booster according to the present invention. FIG. 5 is a circuit diagram showing an embodiment in which the present invention is configured as an AC voltage doubler. FIG. 6 is a circuit diagram showing an embodiment in which a compensation voltage is obtained by using a simple capacitor step-down DC power supply circuit. FIG. 7 is a circuit diagram showing an embodiment in which a compensation voltage is obtained using a simple switching DC power supply circuit. FIG. 8 is a circuit diagram showing an embodiment configured as a power supply device useful for examining a change in characteristics from a change in input power supply voltage. AC: Input AC power supply C1, C2: Capacitor D1, D3: Rectifier diode S1, S2: Capacitor step-down DC power supply circuit or switching DC power supply circuit T1-T4: Switching element D3-T3-R5-R3, D4 -T4-R6-R4 ... Switching element drive circuit ZL ... Load

Claims (6)

(57) [Claims] 1. Two capacitors (C1, C2) are connected in parallel to one terminal of an input AC power supply (AC), and two sets of rectifier circuits are connected to the other terminal of the input AC power supply (AC). Connect in parallel so that the polarities are opposite to each other,
The above two capacitors (C
1, C2) are connected so that they are charged in opposite polarities, and the positive output terminal of one capacitor (C1) and the load (ZL)
Between only one positive terminal of the input AC power supply
The switching element (T1) to be operated is connected in series, and the negative output terminal of the other capacitor (C2) and the load (ZL)
Between the two terminals of the input AC power supply for the negative half cycle
The switching element (T2) to be operated is connected in series, the other terminal of the load (ZL) is connected to the other terminal of the input AC power supply, and the above switching elements (T1, T2) according to the cycle of the input AC power supply (AC) A drive circuit is provided for individually driving on / off the positive and negative voltages of the capacitor (C1) and the positive voltage of the input AC power supply superimposed on both ends of the load (ZL). And a negative voltage obtained by superimposing a negative voltage charged on the other capacitor (C2) on a negative voltage of the input AC power supply. circuit. 2. A rectifier circuit comprising:
2. The capacitor AC booster circuit according to claim 1, wherein the capacitor AC booster circuit is a half-wave rectifier circuit according to 2). 3. The capacitor AC boosting circuit according to claim 1, wherein said rectifying circuit is a capacitor step-down DC power supply circuit or a switching DC power supply circuit (S1, S2). 4. The capacitor AC booster circuit according to claim 1, wherein the rectifier circuit is a half-waveform voltage multiplying rectifier circuit (D3, D5, C3, C5) (D4, D6, C4, C6). 5. The rectifier circuit according to claim 1, wherein the rectifier circuit includes a capacitor step-down DC power supply circuit or a switching DC power supply circuit (S1, S2).
Half-wave voltage multiplying rectifier circuit (D3, D5, C3, C5) (D4, D6, C4,
2. The capacitor AC booster circuit according to claim 1, wherein C6) is combined. 6. A capacitor connected in parallel to one terminal of an input AC power supply (AC) and two sets of switching full waveform double voltage rectifiers to the other terminal of the input AC power supply (AC). The circuits (S1, S2) are connected in parallel so that their output polarities are opposite to each other, and the two capacitors (C1, C2) are charged to the opposite polarities by the respective rectified voltages, and the power supply ( When the algebraic sum of the AC) voltage and the charging voltage of each capacitor (C1 or C2) reaches a predetermined voltage, a switching operation is performed to turn off those charging circuits individually, and the input AC power supply Two switching elements (T1 and T4) that operate on for only half the cycle of (o) for the negative half cycle of the input AC power supply
n Two operating switching elements (T2, T3) are provided, and these four switching elements are connected alternately in a bridge shape. One end of the bridge is connected to the two capacitors (C
1, C2) to the positive output terminal of one capacitor (C1), and the other end of the bridge to the other capacitor (C2)
A capacitor AC booster circuit, characterized in that a load (ZL) is connected between the bridge's midpoint and a negative output terminal.