JPH0759357A - Power converter - Google Patents

Abstract

PURPOSE:To achieve the improvement of power factor and the prevention of a rush current with simple circuit constitution, in case that the power source of a half bridge type of switching regulator out of a rectifier is constituted. CONSTITUTION:A half bridge inverter circuit consisting of first and second switching elements Q1 and Q2, capacitors C11 and C12, and a transformer 7 is connected between a pair of rectified output terminals 5 and 6 of a rectifier 1. A series circuit composed of a smoothing capacitor C1, a reactor L1, and a first diode D1 is connected in parallel with the first switching element Q1. A second diode D2 is connected in parallel with the capacitor C1 and the reactor L1. A third diode D3 is connected between the other end of the second switching element Q2 and the other end of the capacitor C1. The output voltage is controlled by turning on or turning off the first and second switching elements Q1 and Q2 for voltage control with PWM pulses, and also the current of the capacitor C1 is intermitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for connecting to an AC power source to obtain a controlled AC output voltage or DC output voltage.

[0002]

2. Description of the Related Art It is already known that a bridge type inverter having a structure in which four switching elements are bridge-connected or two switching elements in the bridge type inverter are replaced with capacitors to form a half bridge type inverter. The current power supply circuit of this half-bridge type inverter circuit is generally composed of a full-wave rectifier and a smoothing capacitor.

[0003]

By the way, when the capacity of the smoothing capacitor is set to a large value, it is possible to supply a direct current with less ripples and good smoothness to the inverter circuit. However, when the capacity of the smoothing capacitor becomes large,
A voltage with less ripple is held in the capacitor, and a current flows through the rectifier only when the amplitude of the input voltage of the rectifier is higher than the voltage of the capacitor. As a result, a pulsed current flows in the rectifier at and near the maximum amplitude of the input AC voltage, and the power factor becomes low. If a smoothing capacitor with a large capacity is installed, a large inrush current (inrush current) will flow into the smoothing capacitor when the power is turned on (at startup).
Flows. In order to solve the above problems, a switching element is connected to a smoothing capacitor via a reactor, and the switching element is turned on / off at a high frequency to improve the power factor and suppress the inrush current of the capacitor. This is proposed in Japanese Patent Laid-Open No. 60-6664. However, if the smoothing circuit as described above is provided in the preceding stage of the switching circuit for power conversion, the configuration of the device becomes complicated and the cost becomes high.

Therefore, an object of the present invention is to provide a bridge-type or half-bridge type power converter capable of achieving improvement of smoothness, improvement of power factor, and prevention of capacitor inrush current with a relatively simple circuit configuration. To provide.

[0005]

The present invention for achieving the above object comprises an AC power supply terminal to which a sinusoidal AC voltage is supplied and first and second rectified output terminals for sending a rectified output. A rectifier, a first switching element whose one end is connected to the first rectification output terminal, one end of which is connected to the other end of the first switching element, and the other end of which is the second rectification output terminal An inverter circuit for converting a direct current voltage into an alternating current voltage including at least a second switching element connected to the first switching element, and the first and second switching elements at a repetition frequency higher than the frequency of the sine wave alternating current voltage. A control circuit that is turned on and off alternately, an input smoothing capacitor whose one end is connected to the first rectified output terminal, and a reactor whose one end is connected to the other end of the input smoothing capacitor. A first diode connected between the other end of the reactor or this intermediate tap and one end of the second switching element, and between the other end of the reactor and one end of the input smoothing capacitor. And a third diode connected between the other end of the second switching element and the other end of the input smoothing capacitor or the other end of the reactor or the intermediate tap thereof. The present invention relates to a power conversion device equipped with. In addition, as shown in claim 2, it can be configured as a half bridge type. Also, as described in claim 3, 2
A DC output can be obtained by connecting a rectifying / smoothing circuit to the secondary winding. Further, as described in claim 4, a resonance capacitor or a stray capacitance can be provided. Further, as described in claim 5, first and second input smoothing capacitors can be provided. Further, as described in claim 6, an impedance element can be connected between the first and second capacitors via the seventh diode. Further, as shown in claim 7, in the circuit of claim 5 or 6, a rectifying / smoothing circuit can be connected to the secondary winding. In addition, as shown in claim 8, claim 5,
A resonance capacitor or a stray capacitance can be provided in the circuit 6 or 7. Further, as described in claim 9, the connection positions of the first and second capacitors can be changed. Further, as described in claim 10, the second AC power supply terminal can be connected to the interconnection point of the first and second input smoothing capacitors to form a voltage doubler circuit.

[0006]

According to the first, second, fifth and ninth aspects of the present invention, the inverter and the switching element for controlling the voltage are used for improving the power factor and for interrupting the capacitor current for preventing the inrush current. Therefore, it is possible to improve the power factor and prevent the inrush current with a simple circuit configuration. According to the inventions of claims 3 and 6, it is possible to obtain a controlled DC output voltage. According to the inventions of claims 4 and 8,
Resonance operation of the reactor and the resonance capacitor or the stray capacitance occurs, and the rise of the voltage between both terminals of the switching element at the time of OFF becomes slow in accordance with the sine wave. Also,
According to the invention of claim 6, it is possible to precharge up to 1/2 of the rectifier output voltage without relying on the first and second switching elements at the time of startup. As a result, the first and second
The load on the switching element is reduced. Further, according to the invention of claim 10, a doubled voltage can be obtained.

[0007]

[First Embodiment] Next, a power conversion apparatus according to a first embodiment of the present invention will be described with reference to FIGS. The power conversion device of FIG. 1 has a full-wave rectifier 1 at the input stage. This full-wave rectifier 1 comprises AC power supply terminals 2, 3, bridge-connected diodes 4a, 4b, 4c, 4d, and first and second rectified output terminals 5, 6 for delivering a rectified output. . The power converter includes, in addition to the rectifier 1, a primary winding 8 and a secondary winding 9 of a transformer 7, first and second switching elements Q1 and Q2 composed of field effect transistors,
First and second power conversion capacitors C11 and C12, a rectifying / smoothing circuit 10 including a diode and a capacitor,
The DC output terminals 11 and 12, the voltage control circuit 13, the input smoothing capacitor C1, the reactor L1, and the first, second and third diodes D1, D2 and D3 are provided.

Explaining each part in detail, an AC power supply for supplying a commercial AC voltage having a sine wave is connected to the AC power supply terminals 2 and 3. Therefore, a sinusoidal full-wave rectified voltage is obtained between the first and second rectified output terminals 5 and 6. The second rectified output terminal 6 is a ground terminal.

One end (drain) of the first switching element Q1 is connected to the first rectified output terminal 5. Second
Switching element Q2 of the first switching element Q1
Is connected to the other end (source) and the second rectified output terminal 6. The first and second switching elements Q1 and Q2 have a built-in diode connected in antiparallel to the switching element section (between drain and source). One end of the first power conversion capacitor C11 is connected to one end (drain) of the first switching element Q1. The second power conversion capacitor C12 is the first power conversion capacitor C
It is connected between the other end of 11 and the other end of the second switching element Q2. The primary winding 8 of the transformer is connected between the other end (source) of the first switching element Q1 and one end (upper end) of the second power conversion capacitor C12.
In short, the first and second switching elements Q1 and Q2
A typical half-bridge type inverter circuit is constituted by the first and second power conversion capacitors C11 and C12 having substantially the same capacitance value and the transformer 7. An output rectifying / smoothing circuit 10 for obtaining a DC output is connected between the secondary winding 9 and the output terminals 11 and 12.

The voltage control circuit 13 is a well-known constant voltage control circuit and has voltage detection resistors 14 and 15 connected between the output terminals 11 and 12 as shown in FIG. Is connected to one input terminal of the error amplifier 16. A reference voltage source 17 is connected to the other input terminal of the error amplifier 16. Therefore, the error amplifier 16 outputs a voltage corresponding to the difference between the detected voltage value and the reference voltage. The light emitting diode 18 is connected between the output terminal of the error amplifier 16 and the ground. Therefore, for example, when the detection voltage increases and the output voltage of the error amplifier 16 also increases, the intensity of light emission of the light emitting diode 18 increases. The light emitting diode 18 can be connected between the output terminal 11 and the output terminal of the error amplifier 16. The phototransistor 19 optically coupled to the light emitting diode 18 is connected between the DC power supply terminal 21 and the ground via the resistor 20. As the amount of light emitted from the light emitting diode 18 increases, the voltage across the phototransistor 19 decreases. One input terminal of the voltage comparator 22 is the phototransistor 1
9 is connected to the voltage dividing point of the resistor 20, the other input terminal is connected to the triangular wave (sawtooth wave) generation circuit 23, and the output terminal is connected to the distribution circuit 24. Triangle wave generation circuit 2
3 is the frequency of the AC voltage of the power supply terminals 2 and 3 (for example, 60H
Repetition frequency sufficiently higher than z (for example, 20 kHz)
z) generates a triangular wave (sawtooth wave). Therefore, a high level square wave pulse (PWM pulse) is repeatedly generated corresponding to the period when the triangular wave is lower than the voltage of the phototransistor 19, and the distribution circuit 24 alternately turns the first and second switching elements Q1 and Q2. Are distributed to the gates (control terminals) of.

In order to control the charging of the input smoothing capacitor C1 at the output stage of the rectifier 1 by also using the second switching element Q2 for power conversion and voltage control, the reactor L
1 and the first, second and third diodes D1, D2, D
3 are provided. One end of the input smoothing capacitor C1 is connected to the first rectification output terminal 5, and the other end is connected to one end of the reactor L1. First diode D
The anode of 1 is connected to the other end of the reactor L1, and the cathode is one end (drain) of the second switching element Q2.
It is connected to the. The anode of the second diode D2 is connected to the other end of the reactor L1, and the cathode is connected to one end (upper end) of the input smoothing capacitor C1. The anode of the third diode D3 is connected to the other end (source) of the second switching element Q2, and the cathode thereof is connected to the other end (lower end) of the input smoothing capacitor C1. The cathode of the third diode D3 can be connected to the other end of the reactor L1 as shown by the dotted line or to the intermediate tap (not shown) of the reactor L1.

The basic operation of the half-bridge type inverter part of FIG. 1 is as follows. When the power is turned on, first, the first and second power conversion capacitors C11 and C12 are charged by the output voltage of the rectifier 1. Each capacitor C11, C
The charging voltage of 12 becomes 1/2 of the output voltage of the rectifier 1. Next, by alternately distributing the PWM pulses shown in FIG. 4A, the first and second PWM pulses shown in FIGS.
Switching elements Q1 and Q2 are alternately turned on and off. When the first switching element Q1 is on, the first
A current based on the discharge of the first power conversion capacitor C11 flows in a closed circuit composed of the switching element Q1, the primary winding 8, and the first power conversion capacitor C11. If the input smoothing capacitor C1 is already charged, the input smoothing capacitor C1, the first switching element Q1, the primary winding 8 and the second power conversion capacitor C12.
Current also flows from the diode D3 to the closed circuit. After the first and second switching elements Q1 and Q2 are both off, the second switching element Q2
When is turned on, a current flows through a closed circuit composed of the second switching element Q2, the second power conversion capacitor C12 and the primary winding 8, and at the same time the input smoothing capacitor C1 and the first power conversion capacitor are connected. Current also flows in a closed circuit composed of C11, the primary winding 8, the second switching element Q2, and the third diode D3. As a result, a reverse current flows in the primary winding 8 alternately, and an AC voltage is obtained in the secondary winding 9.

By the way, in the circuit of FIG. 1, the smoothing capacitor C1 is not directly connected between the rectified output terminals 5 and 6, but via the reactor L1, the first diode D1 and the second switching element Q2. It is connected. Therefore, the charging current of the smoothing capacitor C1 flows intermittently. First, when the smoothing capacitor C1 is not charged at all and the power is turned on and a sine wave rectified output is generated from the rectifier 1, the smoothing capacitor C1 and the reactor L1 are turned on while the second switching element Q2 is on.
And the first diode D1 and the second switching element Q2
The charging current of the smoothing capacitor C1 flows in the circuit consisting of Next, when the second switching element Q2 is turned off, charging in the above circuit is interrupted. During this interruption period, the reactor L is charged on the basis of the energy accumulated in the reactor L1 during the ON period of the second switching element Q2.
A current flows in a closed circuit of 1 and the second diode D2 and the smoothing capacitor C1, and the smoothing capacitor C1 is charged. When the second switching element Q2 is turned on again,
The charging current of the smoothing capacitor C1 flows again through this. As described above, since the charging current of the capacitor C1 flows by being limited by the on / off of the second switching element Q2, an excessive rush current (inrush current) is generated in the smoothing capacitor C1 when the power is turned on (at start-up). Not flowing.

After the start-up is completed, the voltage Vc of the smoothing capacitor C1 is equal to the rectifier output voltage Vs (provided that the terminal 5,
The voltage becomes higher and lower than the voltage when the capacitor C1 or the like is not connected between 6 and 6 as shown in FIG. 3 (A). Vs as in the section from t1 to t2 in FIG.
When> Vc, the charging current Ic in response to ON / OFF of the second switching element Q2 flows as shown in FIG. 3 (B). The operation in the section from t1 to t2 is the same as that at the start-up described above, and when the second switching element Q2 is on, it is composed of the smoothing capacitor C1, the reactor L1, the first diode D1 and the second switching element Q2. The charging current Ic flows in the circuit. This charging current Ic is shown in FIG.
Increases with time as indicated by t1 to t2. During the OFF period of the second switching element Q2 shown at t2 to t5 in FIG. 4, the reactor L1, the second diode D2 and the capacitor C1 are closed based on the release of the magnetic energy accumulated in the reactor L1 during the ON period. In the circuit, the charging current of the smoothing capacitor C1 flows as shown in the section t2 to t5 of FIG. The current Ic in this section decreases with time. Since the capacitor C1 is charged by the reactor L1 even when the second switching element Q2 is turned on / off, the smoothness of the voltage of the capacitor C1 is relatively good. Further, when the smoothing capacitor C1 is intermittently charged in the section t1 to t2 (section Vs> Vc) in FIG. 3, the peak value of the charging current Ic changes according to the change in the amplitude of the rectified output voltage Vs. As a result, a current that follows the waveform of the sinusoidal AC voltage between the AC power supply terminals 2 and 3 flows through the power supply terminals 2 and 3 to improve the power factor. Note that FIG. 3 (B)
In order to simplify the illustration, the on / off cycle of the capacitor charging current Ic is longer than it actually is.

The voltage of the smoothing capacitor C1 is Vs> Vc
Gradually increases in the section of, and gradually decreases in the section of Vs <Vc. The voltage Vin applied to the series circuit of the first and second switching elements Q1 and Q2 changes as shown in FIG. That is, Vs is added in the section of Vs> Vc,
Vc is added in the section of <Vc. The first and second switching elements Q1 and Q2 control the output voltage by repeating the on / off operation even in the section from t2 to t3 in FIG.

As mentioned above, the second switching element Q2 of FIG. 1 is used both for the inverter and for controlling the charging current of the capacitor C1. Therefore, the control of the output voltage, the improvement of the power factor, and the prevention of the inrush current can be achieved with a simple circuit configuration.

[0017]

[Second Embodiment] Next, a power converter according to a second embodiment will be described with reference to FIG. However, in FIG. 5, the same parts as those in FIG. In the circuit of FIG. 5, the anode of the first diode D1 is connected to the center tap of the reactor L1. A resonance capacitor Ca is connected between the center tap of the reactor L1 and the other end (source) of the second switching element Q2. It should be noted that the capacitance corresponding to the resonance capacitor Ca can be configured as a stray capacitance. In FIG. 5, the configuration other than the above is the same as that in FIG.
When the capacitor Ca is connected, when the second switching element Q2 is off, a resonance circuit composed of the part on the left side of the center tap of the reactor L1, the capacitor Ca and the third diode D3 is formed, and the voltage of the capacitor Ca is sinusoidal. Then, the voltage of the second switching element Q2 also rises like the capacitor Ca. This makes it possible to reduce switching loss and noise when the switching element Q2 is turned off. Further, in the circuit of FIG. 5, only a part of the reactor L1 is used for the resonance circuit to obtain a desired resonance state. Therefore, one reactor L1 enables current limitation when the second switching element Q2 is turned on, charging of the capacitor C1 when the second switching element Q2 is off, and resonance operation when the second switching element Q2 is turned off. When the second diode D2 is turned on, the voltage of the reactor L1 is clamped to the voltage of the capacitor C1, so that the voltage of the resonance capacitor Ca and the voltage of the second switching element Q2 do not exceed the voltage of the capacitor C1. Note that the resonance capacitor Ca can be connected between the right end of the reactor L1 and the ground terminal 6 as shown by the dotted line in FIG. Further, the resonance capacitor Cb can be connected in parallel with the second diode D2.

[0018]

[Third Embodiment] Next, a power conversion system according to a third embodiment will be described with reference to FIG. However, in FIG. 6, the same parts as those in FIGS. 1 and 5 are designated by the same reference numerals, and the description thereof will be omitted.

The circuit shown in FIG. 6 has first and second smoothing capacitors C1 and C2 having substantially the same capacitance value. The first smoothing capacitor C1, the first reactor L1, the first diode D1 and the second switching element Q2 are shown in FIG.
Similarly, is connected in series between the first and second rectified output terminals 5 and 6. The second diode D2 is connected in parallel to the first smoothing capacitor C1 via the first reactor L1. The third diode D3 is connected between the other end of the first smoothing capacitor C1 and the other end (source) of the second switching element Q2. Q2 of FIG.
The interconnections of C1, L1, D1, D2, D3 are identical to these connections of FIG.

The anode of the fourth diode D4 is connected to the other end (source) of the first switching element Q1, and the cathode thereof is connected to one end of the second reactor L2. One end of the second smoothing capacitor C2 is connected to the other end of the second reactor L2, and the other end is connected to the second rectified output terminal (ground) 6. The fifth diode D5 is connected in parallel to the second smoothing capacitor C2 via the second reactor L2. The sixth diode D6 is connected between one end of the second smoothing capacitor C2 and one end of the first switching element Q1.
A resistor R1 as an impedance element is connected between the other end of the first smoothing capacitor C1 and one end of the second smoothing capacitor C2 via a seventh diode D7.

[0021]

[Operation] The basic operation of power conversion by the circuit of FIG. 6 is the same as that of FIG. However, in this embodiment, the PWM pulse is generated with a delay from the voltage control circuit 13 when the power is turned on. This kind of delay is achieved, for example, by delaying the rising of the voltage of the power supply terminal 21 in FIG. When the output of the rectifier 1 is generated during the period in which the first and second switching elements Q1 and Q2 are off due to the delay, the first capacitor C1 and the seventh diode D7 are generated.
The inrush current is limited by the resistor R1 and the current flows in the circuit composed of the current limiting resistor R1 and the second capacitor C2.
The voltage of the second capacitors C1 and C2 is charged to a value that is 1/2 the peak value Vp of the rectified output waveform.

After that, when the first and second switching elements Q1 and Q2 start to turn on / off in response to the PWM pulse, the first and second smoothing capacitors C1 and C2 are charged by the same principle as in FIG. To be done. At this time, since the first and second smoothing capacitors C1 and C2 have been charged to Vp / 2 in advance, the first and second switching elements Q1 and
When Q2 is turned on, the first and second smoothing capacitors C
No large charging current flows to 1 and C2. C1, L1, D1, D2 related to the second switching element Q2
, D3 and the circuits C2, L2, D4, D5, D6 related to the first switching element Q1 perform substantially the same operation. First and second smoothing capacitors C1 and C
The voltage of 2 changes with substantially the same waveform, and a current is supplied to the primary winding 8 by these parallel circuits.
Since the waveforms of the currents flowing through the first and second reactors L1 and L2 are the same, the windings of the first and second reactors L1 and L2 can be wound on the same core.

Since the power converter of FIG. 6 is the same as that of FIG. 1 in the basic operation, it has the same effects as the device of FIG. 1, and further, the first and second switching elements Q1.
, Q2 have the effect of controlling the charging of the capacitors C1 and C2.

[0024]

[Fourth Embodiment] Next, a power conversion system according to a fourth embodiment of the present invention will be described with reference to FIG. However, in FIG. 7, the same parts as those in FIGS. 1 and 6 are designated by the same reference numerals, and the description thereof will be omitted. The circuit of FIG. 7 is configured such that the first and second switching elements Q1 and Q2 are involved in the interruption of the charging current of the first and second smoothing capacitors C1 and C2, and the double voltage output Are selectively obtained. to this end,
It consists of a high frequency capacitor with a smaller capacity than C1 and C2,
First and second auxiliary capacitors Ch1 and Ch2 having substantially the same capacitance value are provided. One end of the first auxiliary capacitor Ch1 is connected to the first rectified output terminal 5.
The second auxiliary capacitor Ch2 is the first auxiliary capacitor Ch1.
Is connected between the other end and the second rectified output terminal 6. A changeover switch S is connected between the interconnection point P1 of the first and second auxiliary capacitors Ch1 and Ch2 and the AC power supply terminal 3. One end of the first smoothing capacitor C1 is connected to the first switching element Q via the first diode D1.
It is connected to one end (drain) of 1 and the other end thereof is connected to one end of the second smoothing capacitor C2 and point P1. The fourth diode D4 is the second switching element Q
It is connected between the other end (source) of 2 and the other end (lower end) of the second smoothing capacitor C2. The first reactor L1 is connected in parallel to the first smoothing capacitor C1 via the second diode D2, and the second reactor L2 is connected in parallel to the second smoothing capacitor C2 via the fifth diode D5. It is connected to the. The third diode D3 is connected between the other end (source) of the first switching element Q1 and the first reactor L1, and the sixth diode D3 is connected.
6 is the second reactor L2 and the second switching element Q
It is connected between one end (drain) of 2.

When the changeover switch S of FIG. 7 is on and the charging voltage of the first smoothing capacitor C1 is higher than the rectifier 1
In the period in which the output voltage of is high, the first AC power supply terminal 2, the diode 4a, the first rectification output terminal 5, the first switching element Q1, the first diode D1, the first reactor L1 and the first The first smoothing capacitor C1 is charged by a circuit composed of the smoothing capacitor C1, the changeover switch S and the second AC power supply terminal 3. Since the first switching element Q1 turns on and off at a frequency higher than that of the AC power supply, the current of the first smoothing capacitor C1 is as shown in FIG.
Is controlled similarly to. While the second AC power supply terminal 3 is in the positive direction, the second AC power supply terminal 3, the changeover switch S, the second smoothing capacitor C2, the second reactor L2, the fourth diode D4 and the second diode The second smoothing capacitor C2 is charged by the circuit composed of the switching element Q2, the second rectified output terminal 6, the diode 4d and the first AC power supply terminal 2. First and second smoothing capacitors C1 and C
2 is almost charged to the power supply voltage, so about 2 of that in FIG.
Double. The first and second switching elements Q1
, Q2 is off, the first and second reactors L1
, L2 are transferred to the capacitors C1, C2 via the diodes D2, D5.

While the rectified output voltage is lower than the voltage of the first and second smoothing capacitors C1 and C2, the first smoothing capacitor C1, the third diode D3 and the first switching element Q1 and 1 are connected. A current flows in a circuit composed of the secondary winding 8, the second power conversion capacitor C12, the sixth diode D6, and the second smoothing capacitor C2, and the first and second smoothing capacitors C1 and C2 supply power. Function as.

When the changeover switch S is off, the operation is almost the same as that of the circuit of FIG. That is, during the ON period of the first switching element Q1, the first rectified output terminal 5, the first switching element Q1, the first diode D1, the first reactor L1, the first smoothing capacitor C1 and the first smoothing capacitor C1. The first smoothing capacitor C1 is charged by the circuit composed of the second auxiliary capacitor Ch2 and the second rectified output terminal 6. Second
Of the first switching element Q2 is ON, the first rectified output terminal 5, the first auxiliary capacitor Ch1, the second smoothing capacitor C2, the second reactor L2, the fourth diode D4, and the second switching capacitor. The second smoothing capacitor C2 is a circuit composed of the element Q2 and the second rectified output terminal 6.
Is charged.

The first and second smoothing capacitors C1 and C
When the voltage of 2 is lower than the power supply voltage (rectified waveform),
The first and second smoothing capacitors C1 and C2 serve as a power source, and the first and fourth smoothing capacitors D1 and D4 are used for the first
Voltage is applied to the circuit of the switching element Q1, the primary winding 8, and the second power conversion capacitor C12, and the circuit of the first power conversion capacitor C11, the primary winding 8, and the second switching element Q2. To do.

The circuit of FIG. 7 has the same effects as the circuits of FIGS. 1, 5 and 6, and has the effect of being able to selectively obtain a doubled voltage.

[0030]

[Fifth Embodiment] A power converter according to a fifth embodiment shown in FIG. 8 will be described below. However, in FIG. 8 and FIG. 9 described later, the same parts as those in FIG. In FIG. 8, the inverter circuits are first to first.
This is a well-known full-bridge type inverter circuit in which the fourth switching elements Q1 to Q4 are bridge-connected. Even with this configuration, the rectifier circuit is the same as in FIG.
The same effect can be obtained.

[0031]

[Sixth Embodiment] The inverter circuit of the sixth embodiment shown in FIG. 9 has a second series circuit of a capacitor C0 and a primary winding 8.
Well-known SEPP connected in parallel with the switching element Q2 of
Circuit (Single Ended Push-Pull)
Circuit). Since the components other than the SEPP circuit of FIG. 9 are the same as those of FIG. 1, the same effects can be obtained.

[0032]

[Modification] The present invention is not limited to the above-mentioned embodiment, and the following modifications are possible. (1) Output terminals 11, 12 without the rectifying / smoothing circuit 10 in the circuits of FIGS. 1, 5, 6, 7, 8 and 9.
AC output can be obtained in the meantime. (2) The voltage control circuit 13 is not limited to that shown in FIG. 2 and can be variously modified. For example, light emitting diode 1
8 and the phototransistor 19 can be omitted. (3) Instead of the changeover switch S shown in FIG. 7, a fixed connection may be used so that a voltage doubler is always obtained. (4) Also in FIGS. 7, 8 and 9, the resonance capacitors Ca and Cb can be provided as in the case of FIG. (5) The switching element Q1 can be a bipolar transistor. In this case, it is desirable to connect a diode to the transistor in anti-parallel.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a power conversion device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing the voltage control circuit of FIG.

FIG. 3 is a waveform diagram showing a state of each part of FIG.

FIG. 4 is a waveform diagram showing a state of the voltage control circuit and a current of a capacitor in FIG.

FIG. 5 is a circuit diagram showing a power conversion device according to a second embodiment.

FIG. 6 is a circuit diagram showing a power conversion device according to a third embodiment.

FIG. 7 is a circuit diagram showing a power conversion device according to a fourth embodiment.

FIG. 8 is a circuit diagram showing a power conversion device according to a fifth embodiment.

FIG. 9 is a circuit diagram showing a power conversion device according to a sixth embodiment.

[Explanation of code] 7 Transformer Q1, Q2 Switching element C1, C2 Smoothing capacitor

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[Procedure amendment]

[Submission date] November 4, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 5

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 6

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 9

[Correction method] Change

[Correction content]

Claims (10)

[Claims] 1. A rectifier having an AC power supply terminal to which a sinusoidal AC voltage is supplied and first and second rectification output terminals for sending a rectified output, and one end of which is connected to the first rectification output terminal. A DC voltage including at least a connected first switching element and a second switching element having one end connected to the other end of the first switching element and the other end connected to the second rectified output terminal. An inverter circuit for converting the AC voltage into an AC voltage, a control circuit for alternately turning ON / OFF the first and second switching elements at a repetition frequency higher than the frequency of the sinusoidal AC voltage, and the first circuit. An input smoothing capacitor whose one end is connected to the rectified output terminal of, a reactor whose one end is connected to the other end of the input smoothing capacitor, and the other end of the reactor or an intermediate thereof. And a second diode connected between the other end of the reactor and one end of the input smoothing capacitor; A power conversion device comprising: a third diode connected between the other end of the second switching element and the other end of the input smoothing capacitor, the other end of the reactor, or the intermediate tap. 2. A rectifier having an AC power supply terminal to which a sinusoidal AC voltage is supplied and first and second rectification output terminals for sending a rectified output, and one end of which is connected to the first rectification output terminal. A connected first switching element, a second switching element having one end connected to the other end of the first switching element and the other end connected to the second rectification output terminal, and one end thereof A first power conversion capacitor connected to one end of the first switching element, one end of which is connected to the other end of the first power conversion capacitor, and the other end of which is the other of the second switching element. A second power conversion capacitor connected to the end, and a transformer 1 connected between the other end of the first switching element and one end of the second power conversion capacitor.
A secondary winding, a secondary winding of the transformer for obtaining an output, and the first and second windings at a repetition frequency higher than the frequency of the sinusoidal alternating voltage for controlling the voltage of the secondary winding.
A voltage control circuit for alternately turning on and off the switching elements of, an input smoothing capacitor whose one end is connected to the first rectification output terminal, and one end of which is connected to the other end of the input smoothing capacitor. Between a reactor, a first diode connected between the other end of the reactor or this intermediate tap and one end of the second switching element, and between the other end of the reactor and one end of the input smoothing capacitor. And a third diode connected between the other end of the second switching element and the other end of the input smoothing capacitor, the other end of the reactor, or this intermediate tap. , A power conversion device comprising. 3. The power conversion device according to claim 2, further comprising a rectifying / smoothing circuit connected to the secondary winding to obtain a DC output. 4. A resonance capacitor or a stray capacitance connected between the other end or intermediate tap of the reactor and the other end of the second switching element. Alternatively, the power conversion device according to 3. 5. A rectifier having an AC power supply terminal to which a sinusoidal AC voltage is supplied and first and second rectification output terminals for sending a rectified output, and one end of which is connected to the first rectification output terminal. A connected first switching element, a second switching element having one end connected to the other end of the first switching element and the other end connected to the second rectification output terminal, and one end thereof A first power conversion capacitor connected to one end of the first switching element, one end of which is connected to the other end of the first power conversion capacitor, and the other end of which is the other of the second switching element. A second power conversion capacitor connected to the end, and a transformer 1 connected between the other end of the first switching element and one end of the second power conversion capacitor.
A secondary winding, a secondary winding of the transformer for obtaining an output, and the first and second windings at a repetition frequency higher than the frequency of the sinusoidal alternating voltage for controlling the voltage of the secondary winding.
A voltage control circuit for alternately turning on and off the switching element of, a first input smoothing capacitor whose one end is connected to the first rectification output terminal, and the other end of the first input smoothing capacitor A first reactor having one end connected thereto, and a first reactor connected between the other end of the first reactor or an intermediate tap thereof and one end of the second switching element.
A second diode connected between the other end of the first reactor and one end of the first input smoothing capacitor, the other end of the second switching element, and the first diode. A third diode connected between the other end of the input smoothing capacitor or the other end of the first reactor or its intermediate tap, and one electrode thereof is connected to the other end of the first switching element. A fourth diode, a second reactor having one end or an intermediate tap thereof connected to the other electrode of the fourth diode, one end thereof connected to the other end of the second reactor, and the other end thereof A second input smoothing capacitor connected to the second rectification output terminal; and a fifth diode connected in parallel to the second input smoothing capacitor via the second reactor. Power converter and a sixth diode connected between one end of one end or the said one end or the center tap of the second reactor a first switching element of said second input smoothing capacitor. 6. A current limiting impedance element connected via a seventh diode between the other end of the first input smoothing capacitor and one end of the second input smoothing capacitor. The power conversion device according to claim 5. 7. The power conversion device according to claim 5, further comprising a rectifying / smoothing circuit connected to the secondary winding to obtain a DC output. 8. A first resonance capacitor or stray capacitance (Ca) connected between the other end of the first reactor or this intermediate tap and the other end of the second switching element, A second resonance capacitor or stray capacitance (Cb) connected between one end of the second reactor or this intermediate tap and one end of the first switching element.
The power conversion device according to claim 5, 6 or 7, further comprising: 9. A rectifier having first and second AC power supply terminals to which a sinusoidal AC voltage is supplied and first and second rectification output terminals for outputting a rectified output, and one end of which is the first rectifier. A first switching element connected to the first rectification output terminal, and a second switching element having one end connected to the other end of the first switching element and the other end connected to the second rectification output terminal An element, a first power conversion capacitor whose one end is connected to one end of the first switching element, one end of which is connected to the other end of the first power conversion capacitor, and the other end of which is the first power conversion capacitor A second power conversion capacitor connected to the other end of the second switching element; and a transformer 1 connected between the other end of the first switching element and one end of the second power conversion capacitor.
A secondary winding, a secondary winding of the transformer for obtaining an output, and the first and second windings at a repetition frequency higher than the frequency of the sinusoidal alternating voltage for controlling the voltage of the secondary winding.
Voltage control circuit for alternately turning on and off the switching element of, a first input smoothing capacitor, a first diode whose one electrode is connected to the other end of the first switching element, and one end of which Or a first reactor having an intermediate tap connected to the other electrode of the first diode and the other end connected to one end of the first input smoothing capacitor; and a first reactor for the first input smoothing capacitor. A second diode connected between the other end and one end of the first reactor, one end of the first input smoothing capacitor, one end of the first reactor or an intermediate tap thereof, and the first A third diode connected between one end of the switching element and a second input smoothing capacitor having one end connected to the other end of the first input smoothing capacitor; A second reactor having one end connected to the other end of the second input smoothing capacitor, and the other end of the second reactor or the intermediate tap thereof and the one end of the second switching element. 4th done
A fifth diode connected between the other end of the second reactor and one end of the second input smoothing capacitor, the other end of the second switching element and the second diode. A sixth diode connected to the other end of the input smoothing capacitor, the other end of the second reactor, or the intermediate tap thereof, and a power converter. 10. A first auxiliary capacitor connected between the first rectified output terminal and one end of the second input smoothing capacitor, and the other end of the first input smoothing capacitor. And a second auxiliary capacitor connected between the second rectification output terminal and the second AC power supply terminal and the connection point of the first and second input smoothing capacitors. The power converter according to claim 9, further comprising means, wherein the rectifier is a bridge type full-wave rectifier.