JPH05161359A - Ac/dc converter - Google Patents

Abstract

PURPOSE:To enable the use of low breakdown voltage elements in the case of constituting converters having circuits for PWM control of switching elements, by improving the point that the breakdown voltages of the switching elements and diodes used for the inverter constitution be more than the output voltage. CONSTITUTION:When the voltage VI of an AC power source 1 is positive, a transistor 3 is turned on and off and a capacitor 10 is charged. And when the voltage VI is negative, a transistor 2 is turned on and off and a capacitor 11 is charged. On this occasion, when the voltage VI is positive and a diode 6 conducts, a diode 8 conducts, and when the voltage VI is negative and a diode 9 conducts, a diode 7 conducts. Accordingly, voltage equal to half the DC output voltage or higher is not applied to any element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention produces a direct current voltage higher than twice the full-wave rectified voltage from an alternating current power source.
The present invention relates to a circuit configuration of a C / DC converter. In the following figures, the same reference numerals indicate the same or corresponding parts.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a main circuit configuration of a conventional AC / DC converter of this type. In FIG. 8, the diode 3
4, 35 and capacitors 10 and 11 constitute a voltage doubler circuit, and the diodes 34 and 35 are respectively provided with the transistor 3
2, 33 are connected in anti-parallel. Further, a reactor 12 is connected in series between the AC input terminal of the voltage doubler circuit and the AC power source 1, and a load 13 is connected to the DC output of the voltage doubler circuit. In such a circuit configuration,
By controlling ON / OFF of the transistor 33 when the voltage VI of the AC power source is positive and by controlling ON / OFF of the transistor 32 when VI is negative, the AC input current becomes a sine wave with a power factor of 1. Then, a DC voltage higher than twice the voltage obtained by full-wave rectifying the AC power supply 1 is output.

FIG. 9 shows another example of the main circuit configuration of a conventional AC / DC converter of this type. In FIG. 9, the diode 3
4, 35, 38 and 39 form a bridge rectification circuit, and transistors 32, 33, 36 and 37 are respectively connected in antiparallel to the diodes 34, 35, 38 and 39 thereof. Further, a reactor 12 is connected in series between the AC input terminal of the bridge rectifier circuit and the AC power supply 1, and a load 13 is connected to the DC output of the bridge rectifier circuit. In such a circuit configuration, when VI of the AC power supply is positive, the on / off of the transistors 33 and 36 is controlled to
When I is negative, ON / OFF of the transistors 32 and 37 is controlled so that the AC input current becomes a sine wave with a power factor ≈1, and a DC voltage higher than the voltage obtained by full-wave rectifying the AC power supply 1 is applied. Output.

[0004]

However, in the above-mentioned conventional circuit system, the switching element and the diode constituting the circuit require an element having a withstand voltage equal to or higher than the DC output voltage value. Therefore, when the output of the device has a large capacity and a high voltage, the number of types of switching elements and diodes that can be used is reduced and there is a restriction. In particular,
When switching at high frequency to reduce the size, weight and performance of the equipment, the number of types of switching elements and diodes that can switch large capacity, high voltage and high frequency becomes extremely small, which is a major limitation. was there. Therefore, the present invention can solve this problem by using AC / D.
An object is to provide a C conversion device.

[0005]

In order to solve the above-mentioned problems, an AC / DC converter according to a first aspect of the present invention comprises a single-phase AC power source (1 or the like), which is at least twice the full-wave rectified voltage. And a single-phase full-bridge rectifier circuit comprising diodes (4,5, 7, 8, etc.), in which the single-phase AC power source is connected to an AC terminal, A switching element (transistor 2, 3, 30,
31), a diode (6, etc.) connected in series between the positive side DC terminal of the single-phase full bridge rectifier circuit and the positive side output terminal (point P) of the AC / DC converter, and Negative side DC terminal of single phase full bridge rectifier circuit and negative side output terminal of this AC / DC converter (N point)
A diode (9, etc.) connected in series between the capacitor and a capacitor connected between the AC terminal (point M) of one of the upper and lower arm pairs of the single-phase full-bridge rectifier circuit and the positive output terminal. (10 or the like) and a capacitor (11 or the like) connected between the AC terminal and the negative electrode side output terminal.

An AC / DC converter according to a second aspect of the present invention is an AC / DC converter that produces a DC voltage that is at least twice the full-wave rectified voltage from a single-phase AC power source (1 or the like). A single-phase full-bridge rectifier circuit composed of diodes (4,5, 7, 8, etc.) having the single-phase AC power source connected to a terminal, and a capacitor (connected between DC terminals of the single-phase full-bridge rectifier circuit ( 14), the positive-side DC terminal of the single-phase full-bridge rectifier circuit, and the AC / DC
A diode (6, etc.) connected in series with the positive side output terminal (point P) of the converter, the negative side DC terminal of the single-phase full bridge rectifier circuit, and the negative side output of the AC / DC converter. A diode (9 or the like) connected in series with a terminal (point N) and a switching element (transistor 2, 3 connected in antiparallel to each of the upper and lower arm pair diodes of the single-phase full-bridge rectifier circuit). Etc.), a capacitor (10 etc.) connected between the AC terminal (point M) of the other pair of upper and lower arms of the single-phase full-bridge rectifier circuit and the positive output terminal, and the AC terminal and the negative electrode. And a capacitor (such as 11) connected to the side output terminal.

According to a third aspect of the present invention, in the AC / DC converter which produces a DC voltage more than twice the full-wave rectified voltage from the N-phase AC power supply, a single-phase full bridge composed of diodes. A rectifier circuit, a switching element that is respectively connected in anti-parallel to the diodes of at least half of the arms of the single-phase full-bridge rectifier circuit, a positive side DC terminal of the single-phase full-bridge rectifier circuit, and this AC / DC conversion. A diode connected in series with the positive side output terminal of the device (point P), a negative side DC terminal of the single-phase full bridge rectifier circuit, and a negative side output terminal of the AC / DC converter (point N). And N sets of diodes connected in series between and, and one AC terminal (point M) of these N single-phase full-bridge rectifier circuits are connected in common to each other, Point and the positive electrode side output terminal, and the common connection point and the negative electrode side output terminal are respectively connected to capacitors (10, 11, etc.) respectively, and the N single-phase full-bridge rectifier circuits are connected. The voltage of each phase of the N-phase AC power supply is applied to the other AC terminal.

An AC / DC converter according to a fourth aspect of the present invention is an AC / DC converter that produces a DC voltage that is twice or more the full-wave rectified voltage of an N-phase AC power supply, and is a single-phase diode. A full-bridge rectifier circuit, a capacitor connected between the DC terminals of the single-phase full-bridge rectifier circuit, a positive-side DC terminal of the single-phase full-bridge rectifier circuit, and a positive-side output terminal of the AC / DC converter (P Connected in series with a negative side DC terminal of the single-phase full-bridge rectifier circuit and a negative side output terminal (N point) of the AC / DC converter. And N switching elements respectively connected in anti-parallel to the diodes of one of the upper and lower arm pairs of the single-phase full-bridge rectifier circuit. The respective phase voltages of the N-phase AC power supply are applied to the AC terminals of the upper and lower arm pairs on the one side, and the AC terminals (point M) of the other upper and lower arm pairs of the N single-phase full-bridge rectifier circuits are common to each other. And a capacitor (10, 11) between the common connection point and the positive electrode side output terminal and between the common connection point and the negative electrode side output terminal, respectively.
And so on).

[0009]

A diode which divides the DC output of the AC / DC converter into two by two series capacitors and clamps the potentials of the positive and negative DC terminals of the bridge rectifier circuit within the potentials of the corresponding series capacitors. Is provided to divide the voltage applied to each switching element and diode. This makes it possible to use a switching element and a diode whose breakdown voltage is lower than the DC output voltage. Therefore, in a device with a large capacity and a high output, MOSF has been difficult to apply because of its low withstand voltage.
The application of high-speed switching elements such as ET becomes easy.
(In general, the higher the breakdown voltage of a semiconductor switching element or diode, the worse the switching performance thereof.)

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) FIG. 1 shows a main circuit configuration of a first embodiment of the invention according to claim 1. In FIG. 1, diodes 4, 5, 7, and 8 form a single-phase bridge rectifier circuit, and an AC power supply 1 is connected to a reactor 12 at an AC input point.
Connected through. Transistors 2 and 3 are connected in antiparallel to the diodes 4 and 5, respectively. The diode 6 is connected in series between the positive electrode side DC terminal of the single-phase bridge rectifier circuit and the positive electrode side output terminal (point P) of the device. The diode 9 is connected to the negative side DC terminal of the single-phase bridge rectifier circuit and the negative side output terminal (N
Points) are connected in series. Further, a capacitor 10 is connected between the points M and P of the diodes 7 and 8 and a capacitor 11 is connected between the points M and N, and a load 13 is connected between the points P and N of the device output. The circuit configuration is connected.

Next, the operation will be described. When the voltage VI of the AC power supply 1 is positive, the transistor 3 is first turned on, and a current is passed through the path of the AC power supply 1 → reactor 12 → transistor 3 → diode 8 → point M → AC power supply 1 to store energy in the reactor 12 ( Mode 1). Next, when the transistor 3 is turned off, the energy stored in the reactor 12 is charged in the capacitor 10 along the path of the AC power supply 1 → reactor 12 → diode 4 → diode 6 → capacitor 10 → M point → AC power supply 1 ( Mode 2). Similarly, when the voltage VI of the AC power supply 1 is negative, the transistor 2 is turned on, and the AC power supply 1 → M point → diode 7
→ Transistor 2 → Reactor 12 → Current is passed through the path of AC power supply 1 to store energy in reactor 12 (mode 3), and when transistor 2 is turned off next, reactor 1
The energy stored in 2 is charged in the capacitor 11 along the route of AC power supply 1 → M point → capacitor 11 → diode 9 → diode 5 → reactor 12 → AC power supply 1 (mode 4). In this way, the transistors 2 and 3 are turned on /
By controlling the OFF, the input current from the AC power supply 1 operates as a so-called step-up voltage doubler rectifier circuit in which the input current becomes a sine wave with a power factor ≈1.

At this time, no voltage higher than that of the capacitor 10 is applied to the diodes 6 and 7 in any operation mode. Further, similarly, the voltage higher than the voltage of the capacitor 11 is not applied to the diodes 8 and 9. Further, regarding the transistor 3 and the diode 5, when the voltage VI of the AC power supply 1 is positive and the transistor 3 is off (mode 2), the series circuit including the transistor 3 and the diode 5 and the diode 9 has a DC output voltage of Although all the voltages are applied, if these elements are selected so that the sum of the leakage currents when the transistor 3 and the diode 5 are off is larger than the leakage current of the diode 9, the transistor 3 is
And the diodes 5 and 9 are respectively capacitors 10
And the voltage of 11 is divided. Similarly, for the transistor 2 and the diode 4, when the voltage VI of the AC power supply 1 is negative and the transistor 2 is off (mode 4), the DC output voltage is applied to the series circuit including the transistor 2 and the diode 4 and the diode 6. However, if these elements are selected so that the sum of the leakage currents when the transistor 2 and the diode 4 are off is larger than the leakage current of the diode 6, the transistor 2 and the diode 4 and the diode 6 are The voltage is divided into the voltages of the capacitors 11 and 10, respectively. This element selection condition is, for example, diodes 4, 5,
This can easily be satisfied by using diodes having the same performance as 6 and 9 and using transistors having an actual leakage current as the transistors 2 and 3.

Next, an example of ON / OFF signals of the transistors 2 and 3 in FIG. 1 is shown in FIG. In FIG. 4, both the ON / OFF signal 28 of the transistor 2 and the ON / OFF signal 29 of the transistor 3 are made by comparing the signal wave 27 and the carrier wave 26, which are made based on the waveform 25 of the AC voltage VI. ..

FIG. 2 shows a main circuit configuration of a second embodiment of the invention according to claim 1. 2 is different from FIG. 1 in that a transistor 30 is connected to the diode 8 in antiparallel in place of the transistor 2 in FIG. This transistor 30 has the same function as the transistor 2 of FIG. That is, when the voltage VI of the AC power supply 1 is negative, by turning on the transistor 30, the AC power supply 1 → M point →
Energy can be stored in the reactor 12 by passing a current through the path of the transistor 30, the diode 5, the reactor 12, and the AC power supply 1.

FIG. 3 shows a third embodiment of the invention according to claim 1, and the difference between FIG. 3 and FIG. 1 is that instead of the transistors 2 and 3 in FIG. 7 in antiparallel.
The transistors 30 and 31 have the same functions as the transistors 2 and 3 of FIG. That is, the operation of the transistor 30 is as described in FIG. Also transistor 31
With regard to, by turning on the transistor 31 when the voltage VI of the AC power supply 1 is positive, a current is passed through the path of the AC power supply 1 → reactor 12 → diode 4 → transistor 31 → M point → AC power supply 1 to the reactor 12. It can store energy.

(2) FIG. 5 shows a main circuit configuration as an embodiment of the invention according to claim 2. FIG. 5 shows a circuit configuration in which a capacitor 14 is added to the circuit configuration shown in FIG. 1 between outer terminals of a pair of upper and lower arms composed of transistors 2 and 3.
Next, the operation will be described. The basic operation is the same as in FIG. 1, and by controlling the on / off of the transistors 2 and 3, the input current from the AC power supply 1 becomes a sine wave with a power factor ≈ 1, so-called step-up type voltage doubler rectification. Operates as a circuit. When the voltage VI of the AC power supply 1 is positive, the transistor 3 is first turned on, and a current is passed through the path of the AC power supply 1 → transistor 3 → diode 8 → M point → AC power supply 1 to store energy in the reactor 12 (mode 1). .. Next, when the transistor 3 is turned off, the energy stored in the reactor 12 is charged on the one hand in the path of the AC power supply 1 → reactor 12 → diode 4 → diode 6 → capacitor 10 → M point → AC power supply 1 ( Mode 2), on the other hand, the capacitor 14 is charged along the path of AC power supply 1 → reactor 12 → diode 4 → capacitor 14 → diode 8 → point M → AC power supply 1 (mode 2).
A).

Therefore, the reactor 12 and the capacitor 14
If the switching frequency of the transistor 3 is sufficiently higher than the resonance frequency of the LC circuit consisting of, the capacitor 14 and the capacitor 1 are charged during the positive half cycle of the voltage VI of the AC power supply 1.
The zero voltage is kept at about the same value. Also, (mode 1)
And (mode 2A), the diode 8 continues to be in the conductive state, and the load 13 is maintained even in (mode 1).
If a sufficient load current flows through the capacitor, capacitor 14 → diode 6 → load 13 → capacitor 11 → diode 8
(Reverse direction) → Since a part of the load current flows through the path of the capacitor 14, the diode 6 can be kept in the conducting state during both the (Mode 1) and (Mode 2). Therefore, even when the transistor 3 switches at high frequency, ordinary diodes (not fast switching) can be applied to the diodes 6 and 8. Even when the voltage VI of the AC power supply 1 is negative, the transistor 2 is used instead of the transistor 3 due to the symmetry of this circuit configuration.
However, since the diode 5 instead of the diode 4, the diode 9 instead of the diode 6, the diode 7 instead of the diode 8 and the capacitor 11 instead of the capacitor 10 have the same functions, respectively, the diodes 7 and 9 are also the same. It allows the application of ordinary (not fast switching) diodes.

In the circuit of FIG. 5, as in FIG. 1, no voltage higher than the voltage of the capacitor 10 or the capacitor 11 is applied to all the elements of the transistors 2 and 3 and the diodes 4 to 9.

(3) FIG. 6 shows a main circuit configuration of an embodiment of the invention according to claim 3. 6, the configuration including transistors 2, 3 and diodes 4 to 9 is the same as that in FIG. 1, and further, transistors 15, 16 and diode 17 are provided.
The same circuit configuration by ~ 22 is the P point, M on the DC output side.
The points and N are connected in common. Further, the capacitors 10 and 11 are respectively points P and M, and points M and N on the DC output side.
The load 13 is connected between the points P and N. Similar to FIG. 1, one terminal of the AC power supply 1 is connected to the midpoint terminal of the pair of upper and lower arms composed of the transistors 2 and 3 via the reactor 12, and the other terminal of the AC power supply 1 is connected via the reactor 23 unlike FIG. Transistor 1
It is a circuit configuration connected to the midpoint terminal of a pair of upper and lower arms composed of 5, 16.

Next, the operation will be described. The basic operation is the same as in FIG. When the voltage VI of the AC power supply 1 is positive, the transistors 3 and 15 are turned on first to turn on the AC power supply 1
→ Reactor 12 → Transistor 3 → Diode 8 → Diode 20 → Transistor 15 → Reactor 23 causes current to flow and stores energy in reactors 12 and 23 (mode 1). At this time, when the magnitude of the voltage VI of the AC power supply 1 is smaller than the voltage of the capacitor 10 or the capacitor 11, either one of the transistor 3 and the transistor 15 is turned off next. When the transistor 3 is turned off, the energy stored in the reactors 12 and 23 is AC power supply 1 → reactor 12 → diode 4
→ Diode 6 → Capacitor 10 → Diode 20 → Transistor 15 → Reactor 23 → AC power source 1 is charged in the capacitor 10 (mode 2).

When the transistor 15 is turned off, the energy stored in the reactors 12 and 23 is AC power source 1 → reactor 12 → transistor 3 → diode 8 → capacitor 11 → diode 22 → diode 18 → reactor 23 → The capacitor 11 is charged along the path of the AC power supply 1 (mode 2A). The magnitude of the voltage VI of the AC power supply 1 depends on the capacitor 10 or the capacitor 1.
When the voltage is higher than the voltage of 1, both the transistor 3 and the transistor 15 are turned off, and the energy stored in the reactors 12 and 23 is AC power supply 1 → reactor 12 → diode 4 → diode 6 → capacitor 10 → capacitor 11 → diode 22. → diode 18 → reactor 2
3 → Capacitor 10 and capacitor 1 in the path of AC power supply 1
Both 1 are charged (mode 2B). Even when the voltage VI of the AC power supply 1 is negative, the transistors 2 and 16 are turned on / off due to the symmetry of this circuit configuration.
The same operation as when the voltage VI is positive is performed. In this operation, by controlling ON / OFF of the transistors 3 and 15 and 2 and 16, the input current from the AC power supply 1 is reduced to the power factor ≈.
It operates as a so-called step-up rectifier circuit that produces a sine wave of 1.

The voltage applied to all the elements of the transistors 2, 3, 15, 16 and the diodes 4 to 9, 17 to 22 satisfies the same condition as shown in (1), so that the capacitor 10 or the capacitor 11 Voltage will not exceed. The positions of the transistors in the two bridge rectification circuits in FIG. 6 may be the positions in FIGS. 2 and 3, which are included in the present invention. Further, even if the two-phase configuration in the modified circuit of FIG. 6 and the above-mentioned FIG. 6 is expanded to N-phase and an N-phase power supply is used, the basic operation is not different and is included in the present invention.

(4) FIG. 7 shows a main circuit configuration as an embodiment of the invention according to claim 4. FIG. 7 is a circuit in which a capacitor 14 is added between the outer terminals of the upper and lower arm pairs composed of transistors 2 and 3 and a capacitor 24 is added between the outer terminals of the upper and lower arm pairs composed of transistors 15 and 16 in the circuit configuration shown in FIG. It is a composition.

Next, the operation will be described. The basic operation is the same as in FIG. 6, except that transistors 2, 3, 15, 16
By controlling the on / off of, the input current from the AC power supply 1 operates as a so-called step-up rectifier circuit that becomes a sine wave with a power factor ≈1. When the voltage VI of the AC power supply 1 is positive, the transistors 3 and 15 are turned on first to turn on the AC power supply 1
→ Reactor 12 → Transistor 3 → Diode 8 → Diode 20 → Transistor 15 → Reactor 23 → Current is passed through the path of AC power supply 1 to store energy in reactors 12 and 23 (mode 1). At this time, the magnitude of the voltage VI of the AC power source 1 depends on the capacitor 10 or the capacitor 11.
When the voltage is smaller than the voltage of, only one of the transistor 3 and the transistor 15 is turned off next. When the transistor 3 is turned off, the energy stored in the reactors 12 and 23 is, on the other hand, the AC power supply 1 → reactor 12 → diode 4 → diode 6 → capacitor 10 → diode 20 → transistor 15 → reactor 23 → AC. The capacitor 10 is charged in the path of the power supply 1 (mode 2), and on the other hand, the AC power supply 1 → reactor 12 →
Diode 4 → Capacitor 14 → Diode 8 → Diode 20 → Transistor 15 → Reactor 23 → AC Capacitor 14 is charged along the path (Mode 2).
A).

When the transistor 15 is turned off, the energy stored in the reactors 12 and 23 is, on the other hand, the AC power source 1 → reactor 12 → transistor 3 → diode 8 → capacitor 11 → diode 22.
→ Diode 18 → Reactor 23 → Capacitor 11 is charged in the path of AC power supply 1 (mode 2B), while AC power supply 1 → Reactor 12 → Transistor 3 → Diode 8 → Diode 20 → Capacitor 24 → Diode 18 → Reactor 23 → The capacitor 24 is charged along the path of the AC power source 1 (mode 2C). The magnitude of the voltage VI of the AC power supply 1 depends on the capacitor 10 or the capacitor 1.
When the voltage is higher than the voltage of 1, both the transistor 3 and the transistor 15 are turned off, and the energy stored in the reactors 12 and 23 is AC power supply 1 → reactor 12 → diode 4 → diode 6 → capacitor 10 → capacitor 11 → diode 22. → diode 18 → reactor 2
3 → Capacitor 10 and capacitor 1 in the path of AC power supply 1
1 both (mode 2D), and then AC power supply 1 →
Reactor 12 → diode 4 → capacitor 14 → diode 8 → diode 20 → capacitor 24 → diode 18 → reactor 23 → recharge both capacitor 14 and capacitor 24 along the path of AC power supply 1 (mode 2
E).

Here, the reactor 12 and the capacitor 1
4 and L consisting of reactor 23 and capacitor 24
If the switching frequency of the transistors 3 and 15 is sufficiently higher than the resonance frequency of the C circuit, the voltage V of the AC power supply 1
During the positive half cycle of I, capacitors 14 and 10, 24 and 1
The voltage of 1 is maintained at about the same voltage. Further, similarly to the circuit of FIG. 5 described in (2), if the load current is sufficiently flowing to the load 13, some of the load current is continuously supplied from the capacitors 14 and 24. ，
21 can continue to be conductive regardless of the switching of the transistors 3 and 15. Even when the voltage VI of the AC power source 1 is negative, the transistors 2 and 16 are turned on / off instead of the transistors 3 and 15 due to the symmetry of the circuit configuration, and the same operation as when the voltage is positive is performed.

From the above, the transistors 2, 3, 15,
Even when the switching of 16 is performed at a high frequency, the diodes 6 to 9 and 19 to 22 can be applied as normal (not high speed switching) diodes with a withstand voltage of about half the DC output voltage. For 16 and the diodes 4, 5, 17, and 18, it is possible to apply an element having a withstand voltage of about half the DC output voltage. Even if the two-phase configuration of FIG. 7 is expanded to N-phase and an N-phase power supply is used, the basic operation is not different and is included in the present invention.

[0028]

According to the present invention, the withstand voltage of the semiconductor element used in this AC / DC converter can be reduced to about half of the DC output voltage, which is generally used in a high-voltage / large-capacity device which has been difficult in the past. It becomes easy to apply a high-speed switching element such as a MOSFET having a low breakdown voltage. As a result, the switching frequency can be increased, and the size and weight of the device can be reduced and the performance can be improved. In particular, claim 2 and claim 4
According to the invention of (1), a general diode having no fast reverse recovery performance can be applied to 2/3 of the diodes used even when performing high frequency switching. There is a trade-off relationship between the high-speed reverse recovery performance of the diode and the price and steady conduction loss. Therefore, it is possible to reduce the price and loss of the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main circuit as a first embodiment of the invention according to claim 1.

FIG. 2 is a configuration diagram of a main circuit as a second embodiment of the invention according to claim 1;

FIG. 3 is a configuration diagram of a main circuit as a third embodiment of the invention according to claim 1.

FIG. 4 is a diagram showing a waveform example of a control signal of the circuit of FIG.

FIG. 5 is a configuration diagram of a main circuit as an embodiment of the invention according to claim 2;

FIG. 6 is a main circuit configuration diagram as an embodiment of the invention according to claim 3;

FIG. 7 is a configuration diagram of a main circuit as an embodiment of the invention according to claim 4;

FIG. 8 is a diagram showing an example of a conventional main circuit configuration.

FIG. 9 is a diagram showing another example of a conventional main circuit configuration.

[Explanation of symbols]

 1 AC Power Supply 2 Transistor 3 Transistor 4 Diode 5 Diode 6 Diode 7 Diode 8 Diode 9 Diode 10 Capacitor 11 Capacitor 12 Reactor 13 Load 14 Capacitor 15 Transistor 16 Transistor 17 Diode 18 Diode 19 Diode 20 Diode 21 Diode 22 Diode 23 Reactor 24 Capacitor Transistor 31 Transistor

Claims (4)

[Claims] 1. An AC / DC converter for producing a DC voltage which is more than twice the full-wave rectified voltage from a single-phase AC power supply, comprising a diode in which the single-phase AC power supply is connected to an AC terminal. A single-phase full-bridge rectifier circuit, switching elements respectively connected in reverse parallel to the diodes of at least half of the arms of the single-phase full-bridge rectifier circuit, and a positive-side DC terminal of the single-phase full-bridge rectifier circuit. A diode connected in series with a positive output terminal of the AC / DC converter, a negative DC terminal of the single-phase full-bridge rectifier circuit, and a negative output terminal of the AC / DC converter. A diode connected in series, and a capacitor connected between the AC terminal of one upper and lower arm pair of the single-phase full-bridge rectifier circuit and the positive output terminal , AC / DC conversion device characterized by comprising a capacitor connected between said the alternating current terminal the negative side output terminal. 2. An AC / DC converter for producing a DC voltage that is twice or more the full-wave rectified voltage of a single-phase AC power supply, comprising a diode in which the single-phase AC power supply is connected to an AC terminal. Single-phase full-bridge rectifier circuit, a capacitor connected between the DC terminals of the single-phase full-bridge rectifier circuit, positive side DC terminal of the single-phase full-bridge rectifier circuit, and positive side output terminal of the AC / DC converter A diode connected in series between the single-phase full-bridge rectifier circuit and a diode connected in series between the negative-side DC terminal of the single-phase full-bridge rectifier circuit and the negative-side output terminal of the AC / DC converter, A switching element respectively connected in anti-parallel to the diodes of one upper and lower arm pair of the single-phase full-bridge rectifier circuit, and the AC terminal of the other upper and lower arm pair of the single-phase full-bridge rectifier circuit. It said a capacitor connected between the positive side output terminal, AC / DC conversion device characterized by comprising connected a capacitor between the and the AC terminal negative-side output terminal. 3. An AC / DC converter for producing a DC voltage more than twice the full-wave rectified voltage from an N-phase AC power supply, and a single-phase full-bridge rectifier circuit comprising a diode, and this single-phase full-bridge. Between a switching element connected in anti-parallel to the diodes of at least half arms of the rectifier circuit, between the positive side DC terminal of the single-phase full-bridge rectifier circuit and the positive side output terminal of the AC / DC converter. N sets of diodes connected in series, and a diode connected in series between the negative-side DC terminal of the single-phase full-bridge rectifier circuit and the negative-side output terminal of the AC / DC converter, One of the AC terminals of the N single-phase full-bridge rectifier circuits is commonly connected to each other, and the common connection point and the positive electrode side output terminal, and the common connection point. A capacitor is connected to each of the negative output terminals, and each phase voltage of the N-phase AC power supply is applied to the other AC terminal of the N single-phase full-bridge rectifier circuits. Characteristic AC / DC converter. 4. An AC / DC converter for producing a DC voltage more than twice the full-wave rectified voltage from an N-phase AC power supply, and a single-phase full-bridge rectifier circuit comprising a diode, and this single-phase full-bridge. A capacitor connected between the DC terminals of the rectifier circuit; a diode connected in series between the positive side DC terminal of the single-phase full-bridge rectifier circuit and the positive side output terminal of the AC / DC converter; A diode connected in series between the negative electrode side DC terminal of the single-phase full-bridge rectifying circuit and the negative electrode side output terminal of this AC / DC converter, and one of the upper and lower arm pair diodes of the single-phase full-bridge rectifying circuit And N sets of switching elements respectively connected in anti-parallel to each other, and the N-phase alternating current terminals are respectively connected to the AC terminals of the one upper and lower arm pairs of the N single-phase full-bridge rectifier circuits. A voltage of each phase of a power source is applied, and the AC terminals of the other upper and lower arm pairs of the N single-phase full-bridge rectifier circuits are commonly connected to each other, and the common connection point and the positive output terminal are connected to each other. , And an AC / DC conversion device, wherein capacitors are individually connected between the common connection point and the negative electrode side output terminal.