JP3240631B2 - Constant voltage / constant frequency power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant-voltage / constant-frequency power supply device used for speed control of small single-phase induction motors, computers, etc., and more particularly to extracting an output voltage twice or half the input voltage. It relates to the improvement of.

[0002]

2. Description of the Related Art As shown in FIG. 6, a typical conventional constant voltage / constant frequency power supply device includes rectifying elements 1a, 1b, 1c, and 1c.
Converter circuit A composed of four 1d connected in series and parallel
And an inverter configured by connecting four switching elements 3a, 3b, 3c, 3d (usually involving a flywheel diode 4 in parallel; the same applies hereinafter) in series and parallel with each other. And a circuit C. One of the AC power input units 7 is connected between the rectifiers 1a and 1b of the converter circuit A, and the other of the AC power input units 7 is connected between the rectifiers 1c and 1d of the converter circuit A. Is connected between the switching elements 3a and 3b of the inverter circuit C, and the other of the AC power output unit 8 is connected between the switching elements 3a and 3b of the inverter circuit C. This power supply device includes a converter circuit A
Since both the inverter circuit C and the inverter circuit C are full bridge circuits, there is a problem that the number of parts is large and the cost is high.

Therefore, the present inventors have invented a variable voltage / variable frequency power supply apparatus shown in FIG. 7 in cooperation with other inventors (Japanese Patent Laid-Open No. 63-314176). In this power supply device, a converter circuit A is configured by connecting two rectifying elements 1a and 1b in series, a smoothing circuit B including smoothing capacitors 2a and 2b is connected to the converter circuit A, and an inverter circuit C is connected to a switching element. 3a, 3b are connected in series, one of the AC power input units 7 is connected between the rectifying elements 1a, 1b of the converter circuit A, and one of the AC power output units 8 is connected to the switching element of the inverter circuit C. 3a,
3b, and the other of the AC power input unit 7 and the other of the AC power output unit 8 are connected by a common line 9.
According to the present invention, the number of components can be reduced by reducing the number of transformers and the filter can be simplified, and an inexpensive and highly accurate power supply device can be obtained.

Subsequently, the present inventors have invented a constant voltage / constant frequency power supply device shown in FIG. 8 in cooperation with other inventors (Japanese Patent Laid-Open No. 231965/1990). This power supply is
The converter circuit A is configured by connecting two rectifying elements 1a and 1b in series, a smoothing circuit B including a smoothing capacitor 2 is connected to the converter circuit A, and the inverter circuit C is connected to two switching elements 3a and 3b in series. And a switching unit D composed of two switching elements 6a and 6b connected in series, connected in parallel to the converter circuit A and the inverter circuit C, and connecting one of the AC power input units 7 to the converter circuit A. And one of the AC power output units 8 is connected between the switching elements 3a and 3b of the inverter circuit C, and the other of the AC power input unit 7 and the other of the AC power output unit 8 are connected to each other. It is connected by a common line 9, and furthermore, the common line 9 is connected between the switching elements 6a and 6b of the changeover switch section D. According to the present invention, a 200V-class output power can be obtained with, for example, a 100V-class element without using a high withstand voltage element, and a compact, inexpensive and highly reliable constant voltage / constant frequency excellent in safety. Power supply could be obtained.

[0005]

However, the power supply circuit shown in FIG. 7 or FIG. 8 is usually used to extract an AC output voltage substantially equal to the AC input voltage. In order to extract a double or 1/2 AC output voltage, a step-up or step-down transformer or a step-up or step-down chopper circuit must be provided. When a step-up or step-down transformer is provided, it is necessary to use a transformer having a large volume and a large weight in order to reduce the decrease in efficiency. When a step-up or step-down chopper circuit is provided, a step-up or step-down rate is required. Therefore, it was necessary to use a reactor having a large inductance. Therefore, in any case, there is a problem that the number of parts increases, the device becomes larger and heavier, the cost increases, and the power loss increases during operation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to obtain an AC output voltage twice or half the AC input voltage while having a small number of parts, small size, light weight and low cost. Another object of the present invention is to provide a new constant-voltage / constant-frequency power supply device with low power loss.

[0007]

In order to achieve the above object, the present invention takes the following measures. First, a power supply device according to claim 1 is for extracting an AC output voltage twice as high as an AC input voltage, and includes a converter circuit configured by connecting at least two rectifying elements or switching elements in series. At least two smoothing capacitors are connected in series, and a smoothing circuit connected in parallel to the converter circuit and an inverter switching circuit arm formed by connecting at least two switching elements in series are connected in two arms in parallel. And an inverter circuit connected in parallel to the smoothing circuit, wherein one of the AC power input units is connected between rectifying elements or switching elements of the converter circuit, and the other of the AC power input units is connected to the smoothing circuit. , And one of the AC power output units is connected to the switch of the one inverter switching circuit arm. As well as connections between switching element,
The other of the AC power output units is connected between switching elements of the other inverter switching circuit arm.

Further, the power supply, characterized in that a changeover switch for selectively connecting the other of said AC power input to the other between the smoothing capacitor or the AC power output of the smoothing circuit And

A second aspect of the present invention is directed to a power supply device for extracting an AC output voltage which is 1/2 times the AC input voltage, wherein at least two rectifying elements or switching elements are connected in series. A converter circuit configured by connecting two converter switching circuit arms in parallel, a smoothing capacitor configured by connecting at least two smoothing capacitors in series, and a smoothing circuit connected in parallel to the converter circuit and at least two switching elements And an inverter circuit connected in parallel to the smoothing circuit, and one of the AC power input units is connected between the rectifying elements or the switching elements of the one converter switching circuit arm, The other of the AC power input sections is connected between the rectifier elements of the other converter switching circuit arm or switched. Connected between elements, thereby connecting the one of the AC power output unit between the switching elements of the inverter circuit, characterized in that the other AC power output unit connected between the smoothing capacitor of the smoothing circuit.

Further, the power supply, the other converter switching circuits arm constituted by connecting switching elements in at least two series, between the smoothing capacitor or the exchange of the other of said AC power output unit the smoothing circuit A changeover switch for selectively connecting to the other of the power input units is provided.

[0011]

According to the first aspect of the present invention, the AC power input from the AC power input section is voltage-double rectified by the converter circuit, and the DC voltage at both ends of the smoothing circuit is the peak value of the AC input voltage. Approximately double. DC power generated at both ends of the smoothing circuit is converted into AC power of a predetermined frequency by an inverter circuit, and an AC output voltage about twice as high as the AC input voltage is taken out from the AC power output unit.

Further, according to this power supply device, when the other side of the AC power input section is connected between the smoothing capacitors of the smoothing circuit by the changeover switch, the AC output of about twice the AC input voltage is produced by the above operation. Voltage can be extracted. When the other side of the AC power input section is connected to the other side of the AC power output section by the changeover switch, the power supply circuit is substantially equivalent to the power supply circuit shown in FIG. 8, and the AC output voltage is substantially the same as the AC input voltage. Can be taken out. Therefore, for example, regardless of whether the AC input voltage is 100 V or 200 V, a constant AC output voltage of 200 V can be obtained by switching the changeover switch.

Next, according to the power supply device of the second aspect,
The AC power input from the AC power input unit is rectified by the converter circuit, and the DC voltage generated in each smoothing capacitor of the smoothing circuit is about 1/2 times the peak value of the AC input voltage. The DC power generated in each of the smoothing capacitors is converted into AC power of a predetermined frequency by an inverter circuit, and an AC output voltage about 1/2 times the AC input voltage is taken out to an AC power output unit.

Further, according to this power supply device, when the other side of the AC power output section is connected between the smoothing capacitors of the smoothing circuit by the changeover switch, the above operation causes the AC input voltage to be about 1/2 times the AC input voltage. AC output voltage can be extracted. When the other side of the AC power output unit is connected to the other side of the AC power input unit by the changeover switch, the power supply circuit is substantially equivalent to the power supply circuit shown in FIG. 8, and the AC output voltage is substantially the same as the AC input voltage. Can be taken out. Therefore, for example, when the AC input voltage is 200 V, the AC output voltage becomes 100 V
V can be selected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a double boost type constant voltage / constant frequency power supply device will be described with reference to FIG. In the figure, A is a converter circuit, which is configured by connecting two rectifying elements 1a and 1b such as diodes in series. B is a smoothing circuit connected in parallel to the converter circuit A, and includes smoothing capacitors 2a and 2b.
Are connected in series.

An inverter circuit C is connected in parallel with the smoothing circuit B. The inverter switching circuit arm C1 includes two switching elements 3a and 3b such as bipolar transistors connected in series, and the switching elements 3c and 3d. , And an inverter switching circuit arm C2 formed by connecting two in parallel. A flywheel diode 4 is connected in parallel between the collector and the emitter of each of the switching elements 3a to 3d.

Reference numeral 7 denotes an AC power input unit connected to the AC power supply 12, one of which is a rectifying element 1 of the converter circuit A.
a and 1b, and the other is connected between the smoothing capacitors 2a and 2b of the smoothing circuit B.

Reference numeral 8 denotes an AC power output unit to which the load 13 is connected, one of which is connected between the switching elements 3a and 3b of the one inverter switching circuit arm C1 and the other is the other inverter switching circuit. It is connected between the switching elements 3c and 3d of the circuit arm C2.

The operation of the first embodiment configured as described above will be described. When the AC power of the AC input voltage Vi is input from the power source 12 to the converter circuit A and the smoothing circuit B through the AC power input unit 7, in the positive half cycle of Vi, the capacity is stored in the smoothing capacitor 2a through the rectifying element 1a. The DC voltage Vi 'corresponding to the load 13 is charged, and the ripple is smoothed. In the negative half cycle of Vi, the DC voltage Vi 'is charged to the smoothing capacitor 2b through the rectifying element 1b, and the ripple is smoothed. Since these smoothing capacitors 2a and 2b are connected in series, the DC voltage at both ends of the smoothing circuit B becomes 2Vi '(double voltage rectification).

The DC voltage 2 generated at both ends of the smoothing circuit B
The DC power of Vi ′ is converted into AC power of a predetermined frequency by the inverter circuit C, and the AC power of the AC output voltage Vo (= 2Vi) is taken out to the AC power output unit 8.
However, this AC output voltage Vo does not become exactly twice the value of the AC input voltage Vi, and the rectifying element 1 of the converter circuit A
a, 1b and the switching elements 3a to 3c of the inverter circuit C.
3d or lower due to a voltage drop in a filter circuit (not shown) and a voltage drop generated during switching.
The switching in the inverter circuit C is as follows.
For example, it can be performed by known PWM (pulse width modulation) control.

As described above, according to the first embodiment, since the converter circuit A is a circuit having half the number of elements of the conventional full bridge circuit, the number of components can be reduced. . Furthermore, since an AC output voltage that is about twice the AC input voltage can be taken out without providing a step-up transformer or a step-up chopper circuit, the number of parts is small, and a compact, lightweight, and inexpensive power supply device is required. This has the effect of reducing power loss during operation.

Next, the constant voltage / constant frequency power supply device of the second embodiment shown in FIG. 2 is different from the first embodiment only in the following points. The converter circuit A is configured by connecting two switching elements 11a and 11b in series. A flywheel diode 4 is connected in parallel to each of the switching elements 11a and 11b. One of the AC power input units 7 is a converter circuit A
Of the reactor 14 between the switching elements 11a and 11b
Connected through. A changeover switch 10 is provided for selectively connecting the other one of the AC power input units 7 between the smoothing capacitors 2a and 2b of the smoothing circuit B or the other one of the AC power output units 8.

The operation of the second embodiment configured as described above will be described. First, the other side of the AC power input unit 7 is switched by the changeover switch 10 to the smoothing capacitor 2 of the smoothing circuit B.
When the connection is made between a and 2b, the same operation as in the first embodiment is performed, and the following operation is added. That is, the switching element 1 of the reactor 14 and the converter circuit A
Since the step-up chopper circuit is formed by 1a and 11b,
By causing the boost chopper circuit to perform an operation of boosting the converted DC voltage by the voltage drop in the converter circuit A and the inverter circuit C, the AC input voltage Vi can be accurately adjusted by a filter (not shown). The double AC output voltage Vo can be extracted from the AC power output unit 8. In addition, if the switching frequency of the switching element of the converter unit is set to a high frequency (for example, 10 kHz or more), a small and lightweight reactor 14 is sufficient.
It hardly leads to an increase in the size and weight of the power supply device.

When the other side of the AC power input section 7 is connected to the other side of the AC power output section 8 by the changeover switch 10, the power supply circuit is substantially equivalent to the power supply circuit shown in FIG.
Furthermore, since the boost by the boost chopper circuit is added,
An AC output voltage Vo that is exactly the same as the AC input voltage Vi can be obtained. Thus, according to the present embodiment,
By simply switching the changeover switch 10, the AC output voltage can be made twice or the same as the AC input voltage, which is very convenient.

Next, a third embodiment in which the present invention is embodied in a 倍 step-down type constant voltage / constant frequency power supply device will be described with reference to FIG. In the figure, E is a converter circuit, and rectifiers 1a and 1b such as diodes.
And a rectifying element 1c, 1 such as a diode.
and d and a converter switching circuit arm E2 formed by connecting two of them in series. F
Is a smoothing circuit connected in parallel to the converter circuit D, and is configured by connecting two smoothing capacitors 2a and 2b in series.

G is an inverter circuit connected in parallel to the smoothing circuit B, and is configured by connecting two switching elements 3a and 3b in series. A flywheel diode 4 is connected in parallel to each of the switching elements 3a and 3b.

One of the AC power input units 7 is connected between the rectifier elements 1a and 1b of the one converter switching circuit arm E1, and the other is connected between the rectifier elements 1c and 1d of the other converter switching circuit arm E2. It is connected. One of the AC power output units 8 is connected between the switching elements 3a and 3b of the inverter circuit G, and the other is connected between the smoothing capacitors 2a and 2b of the smoothing circuit F.

The operation of the third embodiment configured as described above will be described. When the AC power of the AC input voltage Vi is input from the power supply 12 to the converter circuit E through the AC power input unit 7, in the positive half cycle of Vi, the rectifying element 1a → the smoothing capacitor 2a → the smoothing capacitor 2b →
In the loop of the rectifier 1d, the DC voltage Vi 'is charged in the smoothing capacitors 2a and 2b, and the ripple is smoothed. In the negative half cycle of Vi, the DC voltage Vi 'is charged in the smoothing capacitors 2a and 2b in the loop of the rectifying element 1c → the smoothing capacitor 2a → the smoothing capacitor 2b → the rectifying element 1b, and the ripple is smoothed. You. Therefore, a DC voltage Vi '/ 2 is generated at each smoothing capacitor 2a or 2b.

Each smoothing capacitor 2 of the smoothing circuit F
The DC power of the DC voltage Vi ′ / 2 generated at a or 2b is
The power is converted into AC power of a predetermined frequency by the inverter circuit G, and the AC power output unit 8 outputs the AC output voltage Vo (= Vi).
/ 2) AC power is extracted. However, this AC output voltage Vo does not become exactly 1/2 times the value of the AC input voltage Vi, and is further reduced due to a voltage drop in the converter circuit E, the inverter circuit G, and a filter circuit (not shown) and a voltage drop at the time of switching. Lower.

As described above, according to the third embodiment, the number of components can be reduced because the inverter circuit G is a circuit composed of half the number of elements of the conventional full bridge circuit. . Furthermore, since an AC output voltage that is about 1/2 of the AC input voltage can be taken out without providing a step-down transformer or a step-down chopper circuit, the number of parts is small, and a small, lightweight, and inexpensive power supply device can be obtained. This has the effect of reducing power loss during operation.

Next, the constant voltage / constant frequency power supply of the fourth embodiment shown in FIG. 4 differs from the third embodiment only in the following points. One converter switching circuit arm E1 includes switching elements 11a, 11
b are connected in series. A flywheel diode 4 is connected in parallel to each of the switching elements 11a and 11b. One of the AC power input units 7 is connected via a reactor 14 between the switching elements 11a and 11b of the converter switching circuit arm E1.

The fourth embodiment configured as described above performs the same boosting operation as in the second embodiment in addition to the same operation as in the third embodiment, so that the AC input voltage Vi can be exactly one.
An AC output voltage Vo that is twice as large can be extracted from the AC power output unit 8.

Next, the constant voltage / constant frequency power supply device of the fifth embodiment shown in FIG. 5 differs from the fourth embodiment only in the following points. The other converter switching circuit arm E2 also has switching elements 11c and 11c.
The flywheel diode 4 is connected in parallel to each of the switching elements 11c and 11d. A changeover switch 10 is provided for selectively connecting the other one of the AC power output units 8 between the smoothing capacitors 2a and 2b of the smoothing circuit B or the other one of the AC power input units 7.

The operation of the fifth embodiment configured as described above will be described. First, the other side of the AC power output unit 8 is switched by the changeover switch 10 to the smoothing capacitor 2 of the smoothing circuit B.
When the connection is made between a and 2b, the operation is substantially the same as in the fourth embodiment.

When the other side of the AC power output section 8 is connected to the other side of the AC power input section 7 by the changeover switch 10, the power supply circuit is substantially equivalent to the power supply circuit shown in FIG.
Furthermore, since the boost by the boost chopper circuit is added,
An AC output voltage Vo that is exactly the same as the AC input voltage Vi can be obtained. Thus, according to the present embodiment,
By simply switching the changeover switch 10, the AC output voltage V
It is very convenient because o can be made 1/2 times or the same as the AC input voltage Vi.

The present invention is not limited to the configuration of the above-described embodiment, but may be embodied with appropriate modifications without departing from the spirit of the invention, for example, as follows. (1) As a switching element, besides the illustrated bipolar transistor, for example, GTO, MOSFET,
IGBT or the like can be used. (2) When the voltage to be handled is high and the withstand voltage of the element becomes a problem, a converter circuit, a smoothing circuit, or an inverter circuit can be obtained by connecting a larger number of rectifying elements, switching elements, smoothing capacitors, etc. in series than in the above embodiment. May be configured. (3) The constant voltage / constant frequency power supply of the present invention can be applied to, for example, an uninterruptible power supply.

[0037]

As described in detail above, according to the present invention,
It has the following excellent effects. First, according to the power supply device of the first aspect, it is possible to take out an AC output voltage that is about twice the AC input voltage while reducing the number of parts, being small, lightweight, and inexpensive, and reducing power loss.

Further, according to this power supply device, the AC output voltage can be doubled or made the same as the AC input voltage simply by switching the changeover switch, which is convenient.

Next, according to the power supply device of the second aspect ,
With a small number of parts, small size, light weight, and low cost, an AC output voltage that is about half the AC input voltage can be extracted, and power loss is small.

Also, according to this power supply device, the AC output voltage can be made 1/2 times the AC input voltage or the same by simply switching the changeover switch.
It is convenient.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a constant voltage / constant frequency power supply circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a constant voltage / constant frequency power supply circuit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a constant voltage / constant frequency power supply circuit according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a constant voltage / constant frequency power supply circuit according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a constant voltage / constant frequency power supply circuit according to a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a conventional constant voltage / constant frequency power supply circuit.

FIG. 7 is a circuit diagram showing another conventional constant voltage / constant frequency power supply circuit.

FIG. 8 is a circuit diagram showing another conventional constant voltage / constant frequency power supply circuit.

[Explanation of symbols]

1a, 1b, 1c, 1d Rectifying element 2a, 2b Smoothing capacitor 3a, 3b, 3c, 3d Switching element 7 AC power input section 8 AC power output section 10 Changeover switch 11a, 11b, 11c, 11d Switching element 14 Reactor A converter circuit B smoothing circuit C inverter circuit C1, C2 inverter switching circuit arm E converter circuit E1, E2 converter switching circuit arm F smoothing circuit G inverter circuit

Claims (2)

(57) [Claims] A converter circuit configured by connecting at least two rectifying elements or switching elements in series; and a smoothing circuit configured by connecting at least two smoothing capacitors in series and connected in parallel to the converter circuit. An inverter switching circuit arm formed by connecting at least two switching elements in series, comprising two arms connected in parallel, and an inverter circuit connected in parallel to the smoothing circuit; Connecting one of the AC power output units between the switching elements of the one inverter switching circuit arm and connecting the other of the AC power output units to the other inverter switching unit; connected between the switching elements of the circuit arms, the AC power input unit Smoothing capacitor of the smoothing circuit and the other
Or the other of the AC power output sections.
A constant-voltage / constant-frequency power supply device provided with a changeover switch for the power supply. 2. A converter circuit in which at least two rectifying elements or switching elements are connected in series, a converter circuit formed by connecting two arms in parallel, and at least two smoothing capacitors connected in series. A smoothing circuit connected in parallel to the converter circuit, and an inverter circuit configured by connecting at least two switching elements in series and connected in parallel to the smoothing circuit. An AC power output unit connected between the rectifier elements or the switching elements of the one converter switching circuit arm and the other of the AC power input units connected between the rectifier elements or the switching elements of the other converter switching circuit arm; one of connecting between the switching elements of the inverter circuit, wherein Kata of the converter switching circuit arm switch
Also reduce the quenching device constructed by connecting the two series, before
The other side of the AC power output section is connected to the smoothing capacitor of the smoothing circuit.
Or alternatively connected to the other of the AC power input units
Constant voltage switch characterized by providing a changeover switch for
Constant frequency power supply.