JP3092792B2 - Power converter - Google Patents

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 obtaining a DC output or another AC output from a polyphase AC input, and more particularly to a power converter for reducing the number of parts and simplifying a circuit configuration. .

[0002]

2. Description of the Related Art A power converter for obtaining a DC output or another AC output from a polyphase AC input such as three-phase, six-phase or twelve-phase, that is, an AC output having a different number of phases, voltage, frequency, etc., has conventionally been an electronic converter. Widely used in the field of equipment and electrical equipment. For example, in a three-phase converter device as a conventional power converter shown in FIG. 11, rectifier bridge circuits 1 to 3 as rectifier circuits connected via insulating transformers 44 to 46 for each line of a three-phase AC power supply. Rectifies the single-phase alternating current between the lines by full-wave rectification.
Power transistor 7 as switching element in 6
9 through on / off control to convert the rectified output voltages of the rectifier bridge circuits 1 to 3 into a constant DC voltage,
A constant voltage DC output is obtained from the DC output terminals 10 and 11. In FIG. 11, R, S, and T indicate the R, S, and T phases of a three-phase AC power supply, respectively, 44a to 46a are primary windings of insulating transformers 44 to 46, and 44b to 46b are insulating transformers. The secondary windings 44 to 46, 1a to 1d, 2a to 2d and 3a to 3d are first to fourth rectifier diodes constituting rectifier bridge circuits 1 to 3, 12 to 14 are boosting reactors,
Reference numerals 15 to 17 denote reflux diodes, and reference numeral 18 denotes a smoothing capacitor. Power transistor 7 (8, 9), step-up reactor 12 (13, 14), reflux diode 15 (1
6, 17) and the smoothing capacitor 18 constitute the boost chopper circuit 4 (5, 6). In addition, each code in parentheses in the above description has the same order.

[0003]

In a conventional power converter such as a three-phase converter shown in FIG. 11, rectifier diodes 1a to 1d, 2a to 2d and 3a to 3d constituting rectifier bridge circuits 1 to 3 are provided. Since the number of 3d used is as large as 12, there are drawbacks in that the number of components in the entire apparatus increases and the circuit configuration becomes complicated.

Accordingly, an object of the present invention is to provide a power converter that can reduce the number of parts and has a simple circuit configuration.

[0005]

The power converter according to the present invention comprises a plurality of rectifier circuits (19 to 21) which are connected for each line of a polyphase AC power supply and convert single-phase AC between each line to DC. Have. In this power converter, a plurality of rectifier circuits (19
To the first rectifier element (19a to 21a) connected between one phase output terminal between each line of the polyphase AC power supply and one rectification output terminal of the rectifier circuit (19 to 21). A second rectifier element (19b to 21b) connected between the other phase output terminal between the lines of the polyphase AC power supply and one rectification output terminal, and a rectifier circuit (19
21) and a third rectifier element (19c to 21c) connected between any one of the phase output terminals between the lines of the polyphase AC power supply. In addition, multiple rectifier circuits (19 to 2
A converter circuit (4 to 6, 38 to 40) for converting a DC voltage level or an inverter circuit for converting DC to AC is connected to each subsequent stage of 1).

When the voltage of one phase output terminal between one line of the polyphase AC power supply is higher than the voltage of the other phase output terminal, connection is made between the one phase output terminal of the polyphase AC power supply and one line. Rectifier element (19a-21a) of the rectifier circuit (19-21), a converter circuit (4-6, 38-40) connected between the rectifier output terminals of the rectifier circuit (19-21), or an inverter Circuit, the third rectifier element (19c to 21c) of the rectifier circuit (19 to 21) connected between the other lines adjacent to one line, and the current in the path of the other phase output terminal of the polyphase AC power supply. Flows. Also, when the voltage of one phase output terminal between one line of the polyphase AC power supply is lower than the voltage of the other phase output terminal, it is connected between the other phase output terminal of the polyphase AC power supply and one line. Rectifier element (19b-21b) of rectifier circuit (19-21), converter circuit (4-6, 38-40) or inverter circuit connected between rectifier output terminals of rectifier circuit (19-21) A current flows through the path of the third rectifier element (19c to 21c) of the rectifier circuit (19 to 21) connected between one line and one phase output terminal of the polyphase AC power supply. The third rectifier element (19c to 19c) is connected between the other rectification output terminal of the rectifier circuit (19 to 21) and one phase output terminal of the multiphase AC power supply between one line of the polyphase AC power supply. 21c) is the current path when connecting
A third rectifying element (19c to 21c) between the other rectifying output terminal of the rectifying circuit (19 to 21) and the other phase output terminal of the polyphase AC power supply;
Is also substantially the same. For this reason, each of the rectifier circuits (19 to 21) connected between each line of the polyphase AC power supply is constituted by three rectifier elements, respectively, and each rectifier circuit (19 to 2)
Since the number of rectifying elements constituting 1) can be reduced, the number of components of the power converter can be reduced and the circuit configuration can be simplified.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a power converter according to the present invention is applied to a three-phase converter will be described below with reference to FIG. However, in FIG. 1, substantially the same parts as those shown in FIG. 11 are denoted by the same reference numerals, and description thereof will be omitted. Note that, in the following description, the reference numerals in parentheses are in the same order. The three-phase converter device of the embodiment shown in FIG. 1 includes a first (R, S, T) phase output terminal of a three-phase AC power supply and a first reactor connected between the boost reactors 12 (13, 14).
The first rectifier diode 19a (20
a, 21a) and a second rectifier diode 19b as a second rectifier connected between the S (T, R) phase output terminal of the three-phase AC power supply and the boost reactor 12 (13, 14).
(20b, 21b) and a third rectifier diode 19c (20c, 21c) as a third rectifier connected between the DC output terminal 11 and the R (S, T) phase output terminal of the three-phase AC power supply.
The rectifier circuit 19 (20, 21) composed of c) is connected in place of the rectifier bridge circuit 1 (2, 3) in FIG. 11, and the insulating transformer 44 (45, 46) is omitted. However, the third rectifier diode 19c (20c, 21c) in the rectifier circuit 19 (20, 21) includes:
Since the feedback current between the phases flows in common, a large current capacity is used. Other configurations are substantially the same as those of the three-phase converter device shown in FIG.

Next, the operation of the three-phase converter shown in FIG. 1 will be described. When the voltage V _R of the R-phase output terminal of the three-phase AC power supply is higher than the voltage V _S of the S-phase output terminal between the R and S phases of the three-phase AC power supply, the R- The first rectifier diode 19a in the rectifier circuit 19 connected between the S phases, the boost chopper circuit 4 connected between the rectifier output terminals of the rectifier circuit 19, and the load (not shown) connected between the DC output terminals 10 and 11 A current flows through the parallel connection circuit, the third rectifier diode 20c in the rectifier circuit 20 connected between the ST phases, and the path of the S-phase output terminal of the three-phase AC power supply. Also, three-phase AC power supply R-phase output rectifier circuit 19 is the voltage V _R which is connected from the S-phase output terminal of the three-phase AC power supply is lower than the voltage V _S of the S-phase output terminal between R-S phases of the terminal 2nd rectifier diode 1 in
9b, a parallel connection circuit of a boost chopper circuit 4 connected between the rectification output terminals of the rectification circuit 19 and a load (not shown) connected between the DC output terminals 10 and 11, a third rectification diode 19c in the rectification circuit 19, Current flows through the path of the R-phase output terminal of the three-phase AC power supply. The same operation as described above is performed between the ST phase and the TR phase of the three-phase AC power supply. As a result, the full-wave rectified voltages are respectively applied to the boosting reactors 12 to 14 in the boosting chopper circuits 4 to 6 connected to the rectification output terminals of the rectifier circuits 19 to 21, respectively. Further, this allows each boosting reactor 1
The current flowing through 2 to 14 is interrupted by the on / off operation of each of the power transistors 7 to 9, and
5 to 17, the DC output voltage V of a constant voltage boosted to the DC output terminals 10 and 11 at both ends of the smoothing capacitor 18.
_OUT occurs.

Here, the operation of the boosting chopper circuit 4 connected to the rectifier circuit 19 will be further described. When the power transistor 7 is on, the boosting reactor 1 is turned on.
Current flows through 2 and energy is stored. Thereafter, when the power transistor 7 is turned off from the on state, the boosting reactor 1 is turned on during the on period of the power transistor 7.
2 is released to the smoothing capacitor 18 via the reflux diode 15 and
Is boosted and charged. Further, an on / off control signal V _B1 applied to the base terminal of the power transistor 7 in accordance with the voltage between both ends of the smoothing capacitor 18 is subjected to PWM (pulse width modulation).
By controlling, the DC output voltage V _OUT generated at the DC output terminals 10 and 11 is maintained at a constant value. Further, by controlling the on / off control signal V _B1 applied to the base terminal of the power transistor 7 based on the line voltage between the R and S phases of the three-phase AC power supply, the average value of the current flowing through the boost reactor 12 Is controlled in a sinusoidal manner. The same operation as described above is performed also in boost chopper circuits 5 and 6 connected to rectifier circuits 20 and 21, respectively. As a result, phase currents I _RS , I _ST , and I _TR synchronized with the phases of the line voltages between the phases of the three-phase AC power supply flow on the input sides of the boost chopper circuits 4 to 6, respectively. Therefore, the line currents I _R , I _S , I _S from the _R to T phase output terminals of the three-phase AC power source that combine the respective phase currents I _RS , I _ST , and I _TR are described.
_T changes sinusoidally. Also, the three-phase AC power supply R to T
Since the line currents I _R , I _S , and I _T from the phase output terminals are substantially in phase with the respective phase voltages V _R , V _S , and V _{T at the R to T} phase output terminals of the three-phase AC power supply, respectively, The rate is 1.

As described above, in the embodiment shown in FIG.
Voltage V of R (S, T) phase output terminal of three-phase AC power supply
_R (V _S , V _T ) is the voltage V _S (V
_T , V _R ), the current fed back from the R (S, T) phase output terminal to the S (T, R) phase output terminal is ST (T, T R).
-R, R-S) Rectifier circuit 20 (21,
19), the third rectifier diode 20c (21c, 1c).
Since the current flows through 9c), the feedback side rectifier diodes corresponding to the fourth rectifier diodes 1d to 3d of the rectifier bridge circuits 1 to 3 in FIG. For this reason, the rectifier circuits 19 to 21 for each line of the three-phase AC power supply are connected to three rectifier diodes 19a to 19c, 20a to 20c,
1a to 21c, and the number of rectifier diodes can be reduced as compared with the conventional circuit shown in FIG. Therefore,
It is possible to reduce the number of components of the entire power conversion device and to simplify the circuit configuration.

The three-phase converter of the embodiment shown in FIG. 1 can be modified. For example, the three-phase converter device of the embodiment shown in FIG.
6, smoothing capacitors 22 to 24 are connected between the output terminals of the reflux diodes 15 to 17 and the DC output terminal 11 on the feedback side, respectively.
, And individual DC outputs are obtained from the first to third DC output terminals 25 to 27. The operation of each of the boost chopper circuits 4 to 6 is substantially the same as that of the embodiment shown in FIG. In the three-phase converter device shown in FIG. 2, the power transistors 7 to 9 in each of the boost chopper circuits 4 to 6 are individually turned on / off, so that three types of DC output voltages V having different voltage values are obtained.
The _OUT1 ~V _OUT3 can be obtained from between each of the DC output terminal 11 of the first to third DC output terminals 25 to 27 and the feedback side. The boosting reactors 12 to 14 in FIG.
May be connected to the AC input side of each of the rectifier circuits 19 to 21 as shown in FIG. 3, and the same change as described above is possible in the embodiment shown in FIG. Further, as shown in FIG. 4, a circulating current diode 28 and a partial resonance capacitor 29 are additionally connected in front of the power transistor 7 (8, 9) in FIG.
A booster chopper circuit 4 (5, 6) in FIG. 1 may be configured as a booster chopper circuit of a partial resonance type by additionally connecting a transistor 30 for partial resonance, a reactor 31 for partial resonance, and a diode 32 for freewheeling to the subsequent stage. In the circuit shown in FIG. 4, the rising and falling of the switching voltage and current waveform of the power transistor 7 (8, 9) become sinusoidal due to the resonance action, and the zero voltage switching (ZVS) and the zero current switching (ZCS) can be easily performed. As a result, there is an advantage that the switching loss of the power transistor 7 (8, 9) can be reduced. FIG. 5 shows the partial resonance type boost chopper circuit shown in FIG. 4 in which a partial resonance capacitor 33 and a return diode 34 are additionally connected to reduce the switching loss of the partial resonance transistor 30. FIG. 6 shows the switching loss of the partial resonance transistor 30 by additionally connecting the partial resonance capacitor 35 and a series circuit of the partial resonance reactor 36 and the resonance current diode 37 in the partial resonance type boost chopper circuit shown in FIG. Are further reduced. FIG.
6 can be modified in the same manner as the embodiment shown in FIG. 3, in which case the circulating current diode 28 can be omitted.

The three-phase converter device according to the embodiment shown in FIG. 7 is similar to the boost chopper circuits 4 to 6 in the embodiment shown in FIG.
Are step-down chopper circuits 38 to 40 each including a power transistor 7 to 9, a reflux diode 15 to 17, a smoothing reactor 41 to 43, and a smoothing capacitor 18.
It has been changed to. Therefore, the operations and current paths of the rectifier circuits 19 to 21 in the embodiment shown in FIG. 7 are exactly the same as those in the embodiment shown in FIG. In the three-phase converter device shown in FIG.
ON / OFF control signal V _B1 applied to the base terminals
The V _B3 by PWM (pulse width modulation) control, it is possible to obtain a DC output voltage V _{OU T} of the constant voltage stepped down from the DC output terminals 10 and 11. Also, as in the embodiment shown in FIG. 1, the on / off control signals V _{B1 to} V _B3 applied to the base terminals of the power transistors 7 to 9 based on the line voltage between the phases of the three-phase AC power supply are respectively provided. by controlling the phase voltage V _R at R～T phase output terminal of the three-phase AC power supply, V _S, R~T of the three-phase AC power source of V _T and substantially in phase
The input power factor can be set to 1 by controlling each line current I _R , I _S , I _T from the phase output terminal in a sine wave shape.

In the three-phase converter device of the embodiment shown in FIG. 7, the same modifications as in the embodiments shown in FIGS. 2 and 4 to 6 can be made. For example, FIG. 8 shows a modification of the step-down converters 38 to 40 shown in FIG. 7 similar to the embodiment shown in FIG. That is, in the circuit shown in FIG. 8, a circulating current diode 28 and a partial resonance capacitor 29 are additionally connected in parallel with the power transistor 7 (8, 9) in FIG.
A series circuit of the partial resonance transistor 30 and the partial resonance reactor 31 is additionally connected in parallel with the DC output terminal 11 between the connection point of the series circuit of the partial resonance transistor 30 and the partial resonance reactor 31. 7. The step-down chopper circuit 38 in FIG.
(39, 40) is a partial resonance type step-down chopper circuit. Therefore, the circuit shown in FIG. 8 has an advantage that the switching loss of the power transistor 7 (8, 9) can be reduced as in the circuit shown in FIG. FIG. 9 shows FIG.
5 shows a partial resonance type step-down chopper circuit in which a partial resonance capacitor 33 and a return diode 34 are additionally connected to reduce the switching loss of the partial resonance transistor 30 as in the embodiment shown in FIG. FIG.
Corresponds to the partial resonance capacitor 35 and the partial resonance reactor 36 in the partial resonance type step-down chopper circuit shown in FIG.
6 shows a circuit in which the switching loss of the partial resonance transistor 30 is further reduced as in the embodiment shown in FIG. 6 by additionally connecting a series circuit of the resonance current diode 37.

The embodiments of the present invention are not limited to the above embodiments, and various changes can be made. For example, in each of the above embodiments, the third rectifier diode 19c (20c, 21c) constituting the rectifier circuit 19 (20, 21) is connected to the DC output terminal 11 and the R (S, T) phase output terminal of the three-phase AC power supply. Although the form of connection between them has been described, the third rectifier diode 19c (20c, 21c) may be connected between the DC output terminal 11 and the S (T, R) phase output terminal of the three-phase AC power supply.
In the above embodiments, the bipolar power transistors 7 to 9 and 44 to 52 are used as the switching elements. However, instead of the bipolar power transistors, MOS-FETs (MOS field effect transistors), An IGBT (insulated gate field effect transistor), a J-FET (junction field effect transistor), a thyristor, or the like may be used. 1 to 10
In the embodiment shown in FIG. 5, the converter circuit is a boost chopper circuit 4-6 (FIGS. 1-6) or a step-down chopper circuit 38-40.
Although the embodiment is configured as (FIGS. 7 to 10), it may be configured as a step-up / step-down chopper circuit. Further, each converter circuit is not limited to a chopper type converter, and may be configured as another type of converter such as a flyback type or forward type converter, a half bridge type or a full bridge type converter.
Also, in each of the above embodiments, instead of each converter circuit, an inverter circuit for converting DC to AC is connected to the subsequent stage of each of the rectifier circuits 19 to 21, and the rectifier circuits 19 to 21 and each Another AC output may be obtained via an inverter circuit. Further, the present invention is not limited to a three-phase converter device, and can output a DC output or another AC output having a different number of phases, voltage, frequency, etc. from a multi-phase AC input of three or more phases such as six-phase or twelve-phase. Obviously, it can also be applied to the obtained power converter.

[0015]

According to the present invention, the rectifier circuit connected between each line of the polyphase AC power supply can be constituted by three rectifier elements, respectively, so that the number of rectifier elements can be reduced and the entire power converter can be obtained. The number of components can be reduced, and the circuit configuration can be simplified. In particular, the effects of the present invention are remarkable in a power converter that obtains a DC output or another AC output having a different number of phases, voltage, frequency, and the like from a polyphase AC input of three or more phases such as six phases or twelve phases.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment in which a power conversion device according to the present invention is applied to a three-phase converter device.

FIG. 2 is an electric circuit diagram showing a modified embodiment of the three-phase converter device shown in FIG.

3 is an electric circuit diagram showing another modified embodiment of the three-phase converter device shown in FIG.

FIG. 4 is an electric circuit diagram showing a first modified embodiment of the boost chopper circuit shown in FIG. 1;

FIG. 5 is an electric circuit diagram showing a second modified embodiment of the boost chopper circuit shown in FIG. 1;

FIG. 6 is an electric circuit diagram showing a third modified embodiment of the boost chopper circuit shown in FIG. 1;

7 is an electric circuit diagram showing an embodiment in which the step-up chopper circuit of the three-phase converter device shown in FIG. 1 is changed to a step-down chopper circuit.

8 is an electric circuit diagram showing a first modification of the step-down chopper circuit shown in FIG. 7;

9 is an electric circuit diagram showing a second modified embodiment of the step-down chopper circuit shown in FIG. 7;

FIG. 10 is an electric circuit diagram showing a third modified embodiment of the step-down chopper circuit shown in FIG. 7;

FIG. 11 is an electric circuit diagram of a three-phase converter showing a conventional power converter.

[Explanation of symbols]

1-3. . . Rectifier bridge circuit (rectifier circuit), 4 ~
6. . . Boost chopper circuit (converter circuit), 7 ~
9. . . Power transistor (switching element), 1
0,11. . . DC output terminal, 12-14. . . Step-up reactor, 15 to 17, 32, 34. . . Reflux diode, 18, 22-24. . . Smoothing capacitor, 19
~ 21. . . Rectifier circuits, 19a to 21a. . . A first rectifier diode (first rectifier element), 19b to 21b. . . Second rectifier diode (second rectifier), 19c to 21c
c. . . Third rectifier diode (third rectifier), 2
5-27. . . First to third DC output terminals, 28. . .
Circulating current diodes, 29, 33, 35. . . 30. partial resonance capacitor, . . Partial resonance transistor,
31, 36. . . 37. reactor for partial resonance; . . Resonant current diode, 38-40. . . Step-down chopper circuits (converter circuits), 41-43. . . Smoothing reactor, 44-46. . . Insulation transformer, 44a-46
a. . . Primary winding, 44b-46b. . . Secondary winding

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI H02M 7/12 H02M 7/12 W (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 7/00-7 / 40 H02M 3/155

Claims (1)

(57) [Claims] 1. A power conversion device comprising: a plurality of rectifier circuits connected between respective lines of a polyphase AC power supply and configured to convert single-phase alternating current between the respective lines into direct current, wherein each of the plurality of rectifier circuits includes: A first rectifying element connected between one phase output terminal between the lines of the polyphase AC power supply and one rectification output terminal of the rectifier circuit, and the other phase output terminal between the lines of the polyphase AC power supply A second rectifying element connected between the one rectifying output terminal and one of the phase output terminals between the other rectifying output terminal of the rectifying circuit and each line of the polyphase AC power supply. A power converter, comprising: a converter circuit for converting a level of a DC voltage or an inverter circuit for converting a DC voltage to an AC voltage, each of the plurality of rectifier circuits being connected to a subsequent stage. apparatus.