JP2008278713A - Parallel 24-pulse rectifier circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize and reduce the cost of a parallel 24-pulse rectifier circuit by using an AC interphase reactor having a small phase shift angle for the purpose of low-voltage large capacitance requiring an insulation transformer for voltage step-down. <P>SOLUTION: The pulse rectifier circuit includes an AC interphase reactor 3A connected to secondary windings 21, 22 of a three-winding insulation transformer 2, reactors 3B, 3C on the output side thereof, and three-phase bridge rectifiers 1A-1D connected to the output sides of the reactors 3B, 3C and having a DC side connected in parallel. In the reactor 3A, a plurality of windings are magnetically coupled each other so that a magnetomotive force acting to the iron cores of the reactor 3A may be almost zero when the effective value of a current flowing to a first input/output terminal group is equal to that of a current flowing to a second input/output terminal group and a difference in current phase is substantially 30 degrees. In the reactors 3B, 3C, a plurality of windings are magnetically coupled each other so that a magnetomotive force acting to the iron cores of the reactors may be almost zero when the effective values of currents flowing from first and second output terminal groups are equal and the difference in current phase is almost 15 degrees. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rectifier circuit that rectifies a three-phase AC voltage with a three-phase rectifier to obtain a DC voltage, and more particularly to a parallel 24-pulse rectifier circuit in which the DC sides of four three-phase rectifiers are connected in parallel. .

A three-phase bridge rectifier is often used as a power converter that converts three-phase AC power into DC power. Since the three-phase bridge rectifier performs six commutations in one cycle of the power supply, the circuit is also called a six-pulse rectifier circuit. Further, a multi-pulse rectifier circuit such as a 12-pulse rectifier circuit or an 18-pulse rectifier circuit can be configured by combining a plurality of three-phase bridge rectifiers.
Since these multi-pulse rectifier circuits increase the number of commutations, it is well known as an advantage that the harmonic current flowing in the power supply can be reduced and the capacity can be increased.

6 and 7 show a configuration example of a 12-pulse rectifier circuit including two three-phase bridge rectifiers configured by diodes or thyristors. For example, the principle is the same as the circuit described in Non-Patent Document 1. It is.
6 and 7, 1A and 1B are three-phase bridge rectifiers, 2 is one secondary winding is star-connected, the other secondary winding is delta-connected, and the output voltage of both secondary windings is 30 degrees. This is a three-winding insulation transformer having a phase difference of. U, V, and W are three-phase input terminals, and P and N are DC output terminals.

In the circuit of FIG. 6, two three-phase bridge rectifiers 1A and 1B are connected in series, which is suitable mainly for high voltage and large capacity applications.
On the other hand, the circuit of FIG. 7 is a parallel 12-pulse rectifier circuit in which DC circuits of two three-phase bridge rectifiers 1A and 1B are connected in parallel via an interphase reactor 5, and is mainly suitable for low voltage and large capacity applications. . Here, the interphase reactor 5 has the effect | action which suppresses the harmonic current which crosses between the three-phase bridge rectifiers 1A and 1B connected in parallel.
In the circuits of FIGS. 6 and 7, the fifth and seventh harmonics generated by the two three-phase bridge rectifiers 1A and 1B are ideally canceled, so that the harmonics of the power supply can be reduced. Can do.

Next, FIG. 8 is a circuit that is theoretically the same as the circuit described in Non-Patent Document 2.
In this circuit, instead of the insulating transformer 2 shown in FIGS. 6 and 7, an interphase reactor 31 in which three windings are magnetically coupled per phase is used. _{31U 1, 31U 2, 31U 3} , 31V 1, 31V 2, 31V 3, 31W 1, 31W 2, 31W 3 is winding.
Hereinafter, this type of reactor is referred to as an AC phase reactor, and the DC side phase reactor 5 shown in FIG. 7 is referred to as a DC phase reactor.

In FIG. 8, windings of different phases are magnetically coupled to each other in the AC interphase reactor 31, thereby generating a phase shift function between the input and output of the reactor 31.
The number of turns N ₁ , N ₂ , N ₃ of three windings (for example, windings 31 U ₁ , 31 U ₂ , 31 U ₃ ) wound on the same iron core,
N ₁ : N ₂ : N ₃ = 3.73: 2.73: 1.0
By designing to the above, it is possible to configure an AC power source in which the output voltages of the two sets of reactors have a phase difference of 30 degrees, and to supply a three-phase AC voltage having a phase difference of 30 degrees to the rectifiers 1A and 1B. . Thus, the prior art of FIG. 8 attempts to obtain the function of a parallel 12-pulse rectifier circuit similar to the circuit shown in FIG.
In the circuit of FIG. 8, the AC interphase reactor 31 suppresses the cross current flowing between the rectifiers 1A and 1B, so the DC interphase reactor 5 as shown in FIG. 7 is not necessary.

Next, FIG. 9 is a circuit that is theoretically the same as the circuit described in Patent Document 1. Note _that it is _{32U 1, 32U 2, 32U 3} , 32V 1, 32V 2, 32V 3, 32W 1, 32W 2, 32W 3 windings of the AC phase between reactor 32.
In this circuit, the number of turns N ₁ , N ₂ , N ₃ of three windings (for example, windings 32 U ₁ , 32 U ₂ , 32 U ₃ ) wound on the same iron core of the AC interphase reactor 32,
N ₁ : N ₂ : N ₃ = √3: 1: 1
To design. As a result, as in Non-Patent Document 2, the function of a parallel 12-pulse rectifier circuit is to be obtained.

Further, FIG. 10 is the same circuit in principle as the circuit described in Non-Patent Document 3.
This circuit includes AC interphase reactors 31 and 33, and the AC interphase reactor 31 includes windings 31U ₁ , 31U ₂ , 31U ₃ , 31V ₁ , 31V ₂ , 31V ₃ , 31W ₁ , 31W ₂ , 31W ₃ , AC interphase reactor 33 is provided with a winding _{33U 1, 33U 2, 33V 1} , 33V 2, 33W 1, 33W 2.
The windings _33U 1 AC interphase reactors _33, 33V 1, 33 W ₁ is connected between the three phase input terminals U, V, W and the rectifier 1A, the winding _{33U 2,} 33V _2, 33W 2 is 3-phase It is connected between the input terminals U, V, W and the windings 31U ₃ , 31V ₃ , 31W ₃ of the AC interphase reactor 31.
Further, the windings 31U ₁ , 31V ₁ and 31W ₁ of the AC interphase reactor 31 are connected to the rectifier 1B, and the windings 31U ₂ , 31V ₂ and 31W ₂ are connected to the rectifier 1C.

The number of turns N ₁ , N ₂ , N ₃ of the windings wound on the same iron core of the AC interphase reactor 31 (for example, windings 31U ₁ , 31U ₂ , 31U ₃ )
N ₁ : N ₂ : N ₃ = 2.88: 1.88: 1
Are in a relationship.
Thereby, the effective values of the input currents of the rectifiers 1B and 1C connected to the AC interphase reactor 31 are equal and the phase difference is 40 degrees.

On the other hand, the AC interphase reactor 33 does not have a phase shifting function because two in-phase windings are magnetically coupled, but has a function of setting the ratio of the current flowing through the rectifier 1A and the current flowing through the AC interphase reactor 31 to a predetermined value. .
Turns _N 4, _{N 5} turns _N 4 of wound windings on the same core of the AC phase between reactors 33, _{N 5} (e.g. windings _33U 1, 33U ₂₎ is
N ₄ : N ₅ = 1.88: 1
As a result, the effective values of the input currents flowing through the rectifiers 1A, 1B, and 1C are equal, and the phase differences are 0 degrees, +20 degrees, and -20 degrees, respectively, with respect to the rectifier 1A.

  The above phase difference coincides with the phase difference in the case of configuring the 18-pulse rectifier circuit, and the circuit of FIG. 10 is intended to obtain the function of the parallel 18-pulse rectifier circuit. In this case, ideally, the fifth, seventh, eleventh, and thirteenth harmonics do not flow to the power source, and a rectifier circuit having a larger capacity and fewer harmonics than the parallel 12-pulse rectifier circuit is formed. Can do.

"Electrical Engineering Handbook (6th edition)", The Institute of Electrical Engineers of Japan, 20 editions, Power Electronics, pages 846-847 "A New 12-Pulse Rectifier Circuit with Line-Side Interphase Transformer and Nearly Sinusoidal Line Currents" by Manfred Depenbrock and Clemens Niermann, Proc. Of 6th Conference on PEMC, vol.2, pp.374-378 (1990) "A New 18-Pulse Rectifier Circuit with Line-Side Interphase Transformer and Nearly Sinusoidal Line Currents" Proc. Of 1990 IPEC-Tokyo, Vol.1, pp.539-546 (1990) JP 2000-358372 A (Claims 1 and 4, paragraphs [0019] to [0025], FIG. 1, FIG. 2, etc.)

Now, in a DC power source for inverters applied to the induction heating field of metals and a DC power source for electrolysis used in the production of non-ferrous metals, for example, a voltage of several hundred volts and an output of several thousand kW or more are low voltage and large capacity. A DC power supply is required. Since this type of DC power supply is desirably obtained from a high-voltage commercial power supply of 6 kV class or higher, a step-down transformer is required.
In the field as described above, for example, by using the circuit of FIG. 7 described in Non-Patent Document 1, the three-winding transformer 2 is a step-down transformer, thereby constructing a low-voltage and large-capacity rectifier circuit (DC power supply). In addition, the harmonics of the power supply can be reduced. However, in that case, the following problems occur.

For example, when trying to finally obtain a DC voltage of several hundreds V from an AC high voltage of 6 kV or higher, the number of turns of the secondary winding of the three-winding transformer 2 cannot be increased. For this reason, it is necessary to use a step-down three-winding transformer 2 with a large transformation ratio. In this type of three-winding transformer, there is an error in effective value between two sets of secondary voltages on the star side and the delta side. Is likely to occur.
This voltage effective value error appears as a DC voltage error of the two three-phase bridge rectifiers 1A and 1B. However, since the DC voltage error cannot be compensated for by the DC interphase reactor 5, the DC current flowing between the rectifiers 1A and 1B. Ingredient cross current becomes excessive. As a result, the three-phase bridge rectifiers 1A and 1B and the three-winding transformer 2 having a large capacity are required. At the same time, the secondary current of the three-winding transformer 2 includes many fifth and seventh harmonics, and this harmonic also causes an increase in the capacity of the three-winding transformer 2.

  Although not shown in the figure, three units in which the phase difference of the three secondary windings is set to 0 degree, +20 degree, and -20 degrees using a four-winding insulated transformer connected in a staggered manner, and the DC side is connected in parallel. If a bridge rectifier is connected to each secondary winding of the transformer, a parallel 18-pulse rectifier circuit can be constructed. However, this case is the same as the parallel 12-pulse rectifier circuit of FIG. 7 in that the cross current of the DC component flowing between the rectifiers becomes excessive.

On the other hand, the conventional techniques described in Non-Patent Documents 2 and 3 and Patent Document 1 are characterized in that an insulating transformer and a DC interphase reactor are not required. However, with these conventional techniques, as described above, when the AC high voltage is stepped down to finally obtain a predetermined DC voltage, a DC interphase reactor is certainly unnecessary, but it is an alternative to a three-winding transformer. Large and expensive AC interphase reactors 31 and 32 are required.
The reason why the AC phase reactor is large and expensive will be described below.

First, as a first reason, the inter-phase reactors 31 and 32 in Non-Patent Documents 2 and 3 and Patent Document 1 have phase shift characteristics. For this reason, if the phase of the output voltage is changed with respect to the input voltage of the AC phase reactor, a voltage drop of the fundamental wave component due to the phase shift occurs between the input and output of the AC phase reactor, and further, the harmonics A voltage drop due to minutes occurs.
Here, the capacity of the reactor between the AC phases is determined by the product of the voltage obtained by adding the voltage drop of the fundamental component and the voltage drop of the harmonic component and the current flowing through the reactor between the AC phases.

  The capacity of the AC interphase reactor is determined by the voltage drop of the fundamental wave component. However, in determining the capacity of the DC phase reactor 5 shown in FIG. 7, the component corresponding to the voltage drop of the fundamental wave component is determined. There is no. That is, when the AC interphase reactors 31 and 32 are used, the capacity of the AC interphase reactors 31 and 32 is made larger than the capacity of the DC interphase reactor 5 by the voltage drop of the fundamental wave component that is dominant in determining the capacity. There is a need to.

  Further, the AC interphase reactors 31 and 32 of the parallel 12-pulse rectifier circuit shown in FIGS. 8 and 9 perform a phase shift of ± 15 degrees. However, the AC interphase reactor 31 of the parallel 18-pulse rectifier circuit shown in FIG. 10 performs a phase shift of ± 20 degrees. Since the capacity of the reactor increases as the phase shift angle increases, the parallel 18-pulse rectifier circuit of FIG. 10 has a problem in terms of downsizing and cost reduction.

Furthermore, a zero-phase component such as a third-order harmonic also exists in a cross current that flows between a plurality of three-phase bridge rectifiers. If the zero-phase component is to have a cross current suppressing effect, for example, a single-phase reactor is required, and in the case of the parallel 18-pulse rectifier circuit shown in FIG. 10, a total of six single-phase reactors are included. I need it. Therefore, an increase in the number of devices is a factor in increasing the size as compared with the case where a DC phase reactor is used.
In addition, in the parallel 12-pulse rectifier circuit as shown in FIGS. 8 and 9, since the 11th and 13th harmonics exist, there is a case where a harmonic filter must be used together. This will increase the number and size.

  Therefore, the problem to be solved by the present invention is that it is possible to use an AC interphase reactor with a small phase shift angle for a low voltage and large capacity application that requires an insulating transformer for stepping down, thereby reducing the size of the AC interphase reactor and thus the entire circuit. Another object of the present invention is to provide a parallel 24-pulse rectifier circuit that enables a reduction in price.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that, among the first and second three-phase AC power supplies that are insulated from each other and whose output voltage has a phase difference of approximately 30 degrees,
The output of the first three-phase AC power supply is input to the input terminal group of the second interphase reactor via the first input terminal group and the output terminal group of the first interphase reactor,
The output of the second three-phase AC power supply is input to the input terminal group of the third interphase reactor via the second input terminal group and the output terminal group of the first interphase reactor,
The first output terminal group of the second interphase reactor is connected to the input terminal group of the first three-phase rectifier,
A second output terminal group of the second interphase reactor is connected to an input terminal group of the second three-phase rectifier;
The first output terminal group of the third interphase reactor is connected to the input terminal group of the third three-phase rectifier,
The second output terminal group of the third interphase reactor is connected to the input terminal group of the fourth three-phase rectifier,
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is
When the effective value of the current flowing through the first input terminal group and the output terminal group is equal to the current flowing through the second input terminal group and the output terminal group, and the phase difference between these currents is approximately 30 degrees The windings are magnetically coupled to each other so that the magnetomotive force acting on the reactor core is almost zero,
The second and third interphase reactors are
When the effective value of the current flowing out from the first output terminal group of each interphase reactor and the current flowing out from the second output terminal group are equal and the phase difference between these currents is approximately 15 degrees, A plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the reactor core is substantially zero.

In the invention according to claim 2, the three-phase AC power supply is input to the input terminal of the first three-phase isolation transformer via the first winding group of the first interphase reactor, and the first interphase Connected to the input terminal of the second three-phase isolation transformer via the second winding group of the reactor,
The output terminal of the first three-phase isolation transformer is connected to the input terminal group of the first three-phase rectifier through the input terminal group of the second interphase reactor and the first output terminal group,
The output terminal of the first three-phase isolation transformer is connected to the input terminal group of the second three-phase rectifier through the input terminal group and the second output terminal group of the second interphase reactor,
The output terminal of the second three-phase isolation transformer is connected to the input terminal group of the third three-phase rectifier via the input terminal group of the third interphase reactor and the first output terminal group,
The output terminal of the second three-phase isolation transformer is connected to the input terminal group of the fourth three-phase rectifier through the input terminal group and the second output terminal group of the third interphase reactor,
The phase difference between the output voltage of the first three-phase isolation transformer and the output voltage of the second three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
In the first interphase reactor, the number of turns of the first winding group and the second winding group is equal, and the windings wound on the same iron core are magnetically coupled with opposite polarities.
The second and third interphase reactors are
When the effective value of the current flowing out from the first output terminal group of each interphase reactor and the current flowing out from the second output terminal group are equal and the phase difference between these currents is approximately 15 degrees, A plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the reactor core is substantially zero.

In the invention according to claim 3, the three-phase AC power supply is connected to the input terminal of the first three-phase isolation transformer via the input terminal group and the first output terminal group of the first interphase reactor, Connected to the input terminal of the second three-phase isolation transformer via the input terminal group and the second output terminal group of the first interphase reactor,
The first output terminal of the first three-phase isolation transformer is connected to the input terminal group of the first three-phase rectifier through the first input terminal group and the output terminal group of the second interphase reactor,
The second output terminal of the first three-phase isolation transformer is connected to the input terminal group of the second three-phase rectifier through the second input terminal group and the output terminal group of the second interphase reactor,
The first output terminal of the second three-phase isolation transformer is connected to the input terminal group of the third three-phase rectifier through the first input terminal group and the output terminal group of the third interphase reactor,
The second output terminal of the second three-phase isolation transformer is connected to the input terminal group of the fourth three-phase rectifier through the second input terminal group and the output terminal group of the third interphase reactor,
The phase difference between the voltage at the first output terminal and the voltage at the second output terminal of the first three-phase isolation transformer is approximately 30 degrees;
The phase difference between the voltage at the first output terminal and the voltage at the second output terminal of the second three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is
When the effective value of the current flowing out from the first output terminal group is equal to the current flowing out from the second output terminal group and the phase difference between these currents is about 15 degrees, the current of the reactor core The windings are magnetically coupled to each other so that the acting magnetomotive force is almost zero,
The second and third interphase reactors are
When the effective value of the current flowing through the first input terminal group and the output terminal group is equal to the current flowing through the second input terminal group and the output terminal group, and the phase difference between these currents is approximately 30 degrees In addition, a plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the core of the reactor becomes substantially zero.

In the invention according to claim 4, the three-phase AC power supply is connected to the input terminal group of the second interphase reactor via the input terminal group of the first interphase reactor and the first output terminal group, and the first Are connected to the input terminal group of the third interphase reactor via the input terminal group of the interphase reactor and the second output terminal group,
The first output terminal group of the second interphase reactor is connected to the input terminal group of the first three-phase rectifier through the first three-phase isolation transformer,
A second output terminal group of the second interphase reactor is connected to an input terminal group of the second three-phase rectifier through a second three-phase isolation transformer;
The first output terminal group of the third interphase reactor is connected to the input terminal group of the third three-phase rectifier through the third three-phase isolation transformer,
A second output terminal group of the third interphase reactor is connected to an input terminal group of the fourth three-phase rectifier through a fourth three-phase isolation transformer;
The phase difference between the output voltage of the first three-phase isolation transformer and the output voltage of the second three-phase isolation transformer is approximately 30 degrees;
The phase difference between the output voltage of the third three-phase isolation transformer and the output voltage of the fourth three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is:
When the effective value of the current flowing out from the first output terminal group is equal to the current flowing out from the second output terminal group and the phase difference between these currents is about 15 degrees, the current of the reactor core The windings are magnetically coupled to each other so that the acting magnetomotive force is almost zero,
The second and third interphase reactors have the same number of turns of the first winding group connected to the first output terminal group and the second winding group connected to the second output terminal group. In addition, the windings wound on the same iron core are magnetically coupled with opposite polarities.

  According to the present invention, for a low-voltage and large-capacity application that requires an insulation transformer for step-down, the phase-shift function of the insulation transformer, the phase-shift function of the reactor between the AC phases, and the action of current balancing are combined. Thus, a small, inexpensive, and parallel 24-pulse rectifier circuit with less harmonics can be realized.

That is, in the first aspect of the invention, the phase shift function at the output of the second and third AC interphase reactors is ± 7.5 degrees at the maximum, and the increase in the capacity of the AC interphase reactors accompanying the phase shift is suppressed, so The reactor and the entire circuit can be reduced in size and price.
According to the invention of claim 2, while the first AC interphase reactor is connected to the primary side of the first and second isolation transformers, that is, the high voltage side, the current of the AC interphase reactor is reduced, The simplification of the winding configuration associated with can contribute to further miniaturization of the AC phase reactor and the entire circuit.

In the invention of claim 3, it is possible to reduce the size by connecting the first AC interphase reactor to the primary side of the first and second insulation transformers, and the cross current is generated by the action of the insulation transformer. Since it does not flow, it is possible to use a three-phase, three-legged core for the AC interphase reactor, thereby reducing the size and price of the AC interphase reactor.
In the invention of claim 4, since all the AC interphase reactors are connected to the primary side of the insulating transformer, that is, the high voltage side to reduce the current, the reactor can be reduced in size, and compared with claim 3. Thus, the winding configuration of the second and third AC interphase reactors can be simplified.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a first embodiment of the present invention corresponding to claim 1. In FIG. 1, three-phase input terminals U, V, and W connected to a three-phase AC power source have primary windings of a three-winding transformer 2 having first and second secondary windings 21 and 22, respectively. Line 20 is connected.
As shown in the figure, when the first secondary winding 21 is star-connected and the second secondary winding 22 is delta-connected, the phase difference between the output voltages of the first and second secondary windings 21 and 22 is shown. Will be 30 degrees. For this reason, the three-winding insulation transformer 2 having the first and second secondary windings 21 and 22 constitutes the first and second three-phase AC power sources in claim 1.

The secondary winding 21, 22 of the insulating transformer 2 shows one winding and winding turns is N ₄ for each phase is N ₅ wound around and the same core (3-phase 3-legged iron core) above Is connected to the first AC interphase reactor 3 </ b> A. Note that the windings 3AU ₁ , 3AV ₁ , 3AW ₁ having N ₄ turns are connected to the first secondary winding 21, and windings ₃ AU ₂ , 3AU ₃ , 3AV ₂ , 3AV ₃ , 3AW having N ₅ turns are connected. ₂ and 3AW ₃ are connected to the second secondary winding 22. Furthermore, the winding 3AU ₂ in 3AW _3, the winding 3AV ₂ is 3AU _3, winding 3AW ₂ are connected to the 3AV _3.
Here, the turn ratio of the winding is
N ₄ : N ₅ = √3: 1
It has become.

FIG. 2 is a phasor diagram for explaining the operation of the AC interphase reactor 3A.
In FIG. 2, I _U1 , I _V1 , and I _W1 are currents on the windings 3AU ₁ , 3AV ₁ , 3AW ₁ side connected to the secondary winding 21 of the star connection (advanced side), I _U2 , I _V2 , I _W2 is the current on the windings 3AU ₂ , 3AU ₃ , 3AV ₂ , 3AV ₃ , 3AW ₂ , 3AW ₃ side connected to the secondary winding 22 of the delta connection (slow phase side) (note that the specification text) (The dot indicating the vector is omitted.) The broken line indicates the product of the number of turns acting on the U-phase iron core and the current, that is, the magnetomotive force.
The currents I _U1 and I _V2 are magnetically coupled in the same polarity, the current I _U2 is magnetically coupled in the opposite polarity to these, and the winding turns ratio N ₄ : N ₅ is set as described above. The resultant magnetomotive force acting on the phase iron core is a closed triangle as shown in the drawing, that is, zero.

  By the way, the AC interphase reactor acts so that the sum of magnetomotive forces by the windings wound on the same iron core is ideally zero. Therefore, when there is an error in the effective value in the voltage of the secondary windings 21 and 22 of the isolation transformer 2, the magnetomotive force acting on the same iron core acts so as to become zero. , 22 are equal to each other. In this case, the AC interphase reactor 3 </ b> A does not have a phase shift function, but has only a function for compensating for a secondary voltage error of the isolation transformer 2. This is because the input voltage of the AC interphase reactor 3 </ b> A is phase-shifted by the insulation transformer 2.

Further, the windings 3AU ₁ , 3AV ₁ , 3AW ₁ of the first AC interphase reactor 3A are connected to the second AC interphase reactor 3B, and the windings 3AU ₃ , 3AV ₃ , 3AW ₃ of the reactor 3A are the third It is connected to AC phase reactor 3C.
Here, in the second and third AC interphase reactors 3B and 3C, three windings are magnetically coupled per phase, and 3U ₁ , 3U ₂ , 3U ₃ , 3V ₁ , 3V ₂ , 3V ₃ , 3W ₁ , 3W ₂ and 3W ₃ denote windings. Note that the number of turns of the windings 3U ₁ , 3V ₁ , 3W ₁ is N ₁ , the number of turns of the windings 3U ₂ , 3V ₂ , 3W ₂ is N ₂ , and the number of turns of the windings 3U ₃ , 3V ₃ , 3W ₃ is N ₃ . To do.

The windings 3U ₁ , 3V ₁ , 3W ₁ of the second AC interphase reactor 3B are connected to the AC circuit of the first three-phase bridge rectifier 1A, and the windings 3U ₂ , 3V ₂ , 3W ₂ are the second three-phases. It is connected to the AC circuit of the bridge rectifier 1B. The windings 3U ₁ , 3V ₁ , 3W ₁ of the third AC phase reactor 3C are connected to the AC circuit of the third three-phase bridge rectifier 1C, and the windings 3U ₂ , 3V ₂ , 3W ₂ are connected to the fourth It is connected to the AC circuit of the three-phase bridge rectifier 1D.
The DC circuits of the first to fourth three-phase bridge rectifiers 1A to 1D are connected in parallel, and a smoothing capacitor 4 is connected between the positive and negative DC terminals P and N.

In the second and third AC interphase reactors 3B and 3C, when the direction of the current flowing through the first to fourth three-phase bridge rectifiers 1A to 1D is defined as the positive direction of the AC current, the windings 3U ₁ , 3V ₁ , 3W ₁ and windings 3U ₃ , 3V ₃ , 3W ₃ are magnetically coupled with the same polarity, and windings 3U ₂ , 3V ₂ , 3W ₂ are magnetically coupled with the opposite polarity.
The configuration of the second and third AC interphase reactors 3B and 3C is the same as that of the AC interphase reactor 31 of FIGS. 8 and 10, but here, the turn ratio described above is
N ₁ : N ₂ : N ₃ = 7.08: 6.08: 1
Is set to
In practice, the turn ratio may be 7: 6: 1.

As a result, the phase shift function at the outputs of the two sets of the second and third AC interphase reactors 3B and 3C is ± 7.5 degrees.
As a result, assuming that the input phase of the three-phase bridge rectifier 1D is a reference phase, the input phases of the three-phase bridge rectifiers 1A to 1D are 45 degrees, 30 degrees, 15 degrees, and 0 degrees. Operates as a rectifier circuit.
In the present embodiment, the three-winding insulation transformer 2 is used as the insulation transformer. However, similar effects can be obtained by using two two-winding transformers. Further, in order to smooth the direct current, the output terminals of the three-phase bridge rectifiers 1A to 1D may be connected in parallel via a direct current reactor.

  The phase shift function of the AC phase reactors 31 and 32 for the conventional parallel 12-pulse rectifier circuit shown in FIGS. 8 and 9 is ± 15 degrees, and the conventional AC phase reactor for the parallel 18-pulse rectifier circuit shown in FIG. 31 has a phase shift function of ± 20 degrees, but according to this embodiment, since the phase shift function is ± 7.5 degrees at the maximum, the capacity of the reactors 3B and 3C between the AC phases accompanying the phase shift By suppressing the increase, the reactor and the entire circuit can be reduced in size and cost. A parallel 24 pulse rectifier circuit can provide a rectifier circuit with a large capacity and less harmonics.

Next, FIG. 3 is a circuit diagram of a second embodiment of the present invention corresponding to claim 2. The same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different portions will be mainly described.
In the second embodiment, the first AC interphase reactor 3D is connected to the primary side of the first and second insulation transformers 2A and 2B.
In the low-voltage and large-capacity rectifier circuit, the output current becomes a large current, which may make it difficult to manufacture the reactor. For this reason, in this embodiment, AC phase reactor 3D is connected to the primary side of insulation transformer 2A, 2B, ie, a high voltage circuit, and an electric current value is reduced. Further, the AC phase reactor 3D is connected to the primary side of the isolation transformers 2A and 2B, so that the currents flowing through the first output terminal group and the second output terminal group of the AC phase reactor 3D have the same phase. . As a result, the AC interphase reactor 3D can be configured with two windings having the same number of turns magnetically coupled to the opposite polarity on the same iron core, and thus the configuration can be simplified and the size can be reduced.

The AC interphase reactor 3D includes windings 3DU ₁ , 3DU ₂ , 3DV ₁ , 3DV ₂ , 3DW ₁ , 3DW ₂ connected to the three-phase input terminals U, V, W, and windings 3DU ₁ , 3DV ₁ , 3DW. ₁ is connected to the primary winding 2A ₁ of the first isolation transformer 2A, winding _{3DU 2,} 3DV 2, 3DW ₂ is connected to the primary winding 2B ₁ of the second isolation transformer 2B The Each of the two windings connected to the three-phase input terminals U, V, and W is magnetically coupled to each other with a reverse polarity.
Even if there is an error in the transformation ratio of the insulation transformers 2A and 2B, the primary currents of the insulation transformers 2A and 2B become equal due to the action of the two windings magnetically coupled to the opposite polarity of the AC interphase reactor 3D. As a result, the secondary current is also substantially equal.

Since the primary windings 2A ₁ and 2B ₁ of the isolation transformers 2A and 2B are both delta connections, one of the secondary windings 2A ₂ is a star connection and the other secondary winding 2B ₂ is a delta connection. The phase difference between the secondary voltages of the isolation transformers 2A and 2B is 30 degrees.
The secondary winding 2A _{and second} isolation transformer 2A is connected to a second AC interphase reactor 3B, the secondary winding 2B ₂ insulating transformer 2B is connected to a third alternating interphase reactors 3C. The connection and turn ratio of these AC interphase reactors are the same as those of the AC interphase reactors 3B and 3C in FIG. 1, and the phase shift function at the two sets of outputs of the reactors 3B and 3C is ± 7 as in the first embodiment. .5 degrees.
Similarly, the AC circuits of the first to fourth three-phase bridge rectifiers 1A to 1D are connected to the output terminals of the reactors 3B and 3C, as described above.

Also in this embodiment, assuming that the input phase of the three-phase bridge rectifier 1D is a reference phase, the input currents of the three-phase bridge rectifiers 1A to 1D have the same effective value, and the input phases are 45 degrees, 30 degrees, 15 degrees, Since this is 0 degree, this rectifier circuit operates as a parallel 24-pulse rectifier circuit.
According to this embodiment, the first AC interphase reactor 3D is connected to the primary side of the first and second isolation transformers 2A and 2B, that is, to the high voltage side for the purpose of the present invention, thereby reducing the current. In addition, the winding configuration of the reactor 3D can be simplified accordingly, so that the reactor and the entire circuit can be reduced in size.

  Next, FIG. 4 is a circuit diagram showing a third embodiment of the present invention corresponding to the third aspect. The characteristic part in comparison with the first embodiment is that the first AC interphase reactor 3B having a phase shift function of ± 7.5 degrees is the first and second three-winding insulation transformers 2, 2 ′. It is connected to the primary side.

The first AC interphase reactor 3B has the same configuration as the AC interphase reactor 3B (and 3C) in FIG. 3, and the windings 3U ₃ , 3V ₃ , 3W ₃ are connected to the three-phase input terminals U, V, W. ing. The windings 3U ₁ , 3V ₁ , 3W ₁ are connected to the primary winding of the first three-winding insulation transformer 2, and the windings 3U ₂ , 3V ₂ , 3W ₂ are the second three-winding insulation. It is connected to the primary winding of the transformer 2 ′. For this reason, the primary voltages of the first and second three-winding isolation transformers 2 and 2 ′ have a phase difference of ± 7.5 degrees.

The configuration of the first and second three-winding insulation transformers 2 and 2 ′ is the same as that of the insulation transformer 2 in FIG. 1, and in each case, the primary winding is a delta connection and the first secondary winding is a star. The connection and the second secondary winding are delta connections.
The first and second secondary windings of these transformers 2 and 2 'are connected to second and third AC interphase reactors 3A and 3E having the same configuration as the AC interphase reactor 3A in FIG. Incidentally, the AC phase between reactors 3A, in _{3E, 3AU 1, 3AV 1,} 3AW 1, 3EU 1, 3EV 1, 3EW 1 the winding of the turns is _{N 4, 3AU 2, 3AU 3} , 3AV 2, 3AV 3, 3AW 2 , 3AW ₃ , ₃ EU ₂ , ₃ EU ₃ , ₃ EV ₂ , ₃ EV ₃ , ₃ EW ₂ , ₃ EW ₃ are windings with N ₅ turns, and these windings are secondary winding voltages of the transformers 2, 2 ′. It has a function to compensate for the RMS value error.
The two sets of three-phase output terminals of the second and third AC interphase reactors 3A and 3E are respectively connected to the AC circuits of the first to fourth three-phase bridge rectifiers 1A to 1D in which DC circuits are connected in parallel. It is connected.

  According to this embodiment, when the input phase of the three-phase bridge rectifier 1D is a reference phase, the input current of the three-phase bridge rectifiers 1A to 1D has the same effective value, and the input phase is 45 degrees, 15 degrees, Since 30 degrees and 0 degrees, this rectifier circuit operates as a parallel 24-pulse rectifier circuit.

In particular, in this embodiment, the phase shift of ± 20 degrees is conventionally performed only by the AC interphase reactor, but by using the isolation transformers 2 and 2 ′ that perform the phase shift of ± 30 degrees, The voltage drop of the fundamental wave component in the AC interphase reactors 3A and 3E is almost zero, and the first AC interphase reactor 3B that performs a phase shift of ± 7.5 degrees can be connected to the high voltage circuit to reduce the current. As a result, the AC phase reactors 3A, 3E, 3B can be reduced in size and price.
In the first and second embodiments, in order to suppress the cross current flowing between the first and second three-phase bridge rectifiers 1A and 1B and the third and fourth three-phase bridge rectifiers 1C and 1D, the second As the third AC interphase reactors 3B and 3C, it is necessary to use three single-phase reactors or three-phase reactors having a five-legged core. On the other hand, in this embodiment, since the above-mentioned cross current does not flow by the action of the insulation transformers 2 and 2 ′, an inexpensive three-phase three-legged core can be used, which further contributes to downsizing and cost reduction. .

Next, FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention corresponding to the fourth aspect.
The characteristic part when compared with the first embodiment is that the first to third AC interphase reactors 3B, 3D, 3F are connected to the primary side of the insulation transformer, and as an insulation transformer Uses first to fourth two-winding insulation transformers 2A to 2D.

The first AC interphase reactor 3B has the same configuration as the AC interphase reactor 3B (and 3C) in FIG. 3, and the windings 3U ₃ , 3V ₃ , 3W ₃ are connected to the three-phase input terminals U, V, W. ing. Further, the output voltages of the windings 3U ₁ , 3V ₁ and 3W _{1 and} the output voltages of the windings 3U ₂ , 3V ₂ and 3W ₂ have a phase difference of ± 7.5 degrees. The second and third AC interphase reactors 3D and 3F have the same configuration as the AC interphase reactor 3D in the second embodiment of FIG. 3, and each have the same number of turns (N ₄ ) magnetically coupled to the opposite polarity on the same iron core. ) Windings 3DU ₁ , 3DU ₂ , 3DV ₁ , 3DV ₂ , 3DW ₁ , 3DW ₂ and windings 3FU ₁ , 3FU ₂ , 3FV ₁ , 3FV ₂ , 3FW ₁ , 3FW ₂ .

The first and third isolation transformers 2A and 2C have a delta connection for the primary winding, a star connection for the secondary winding, and the primary windings for the second and fourth isolation transformers 2B and 2D. The delta connection and the secondary winding are also delta connections.
The windings 3DU ₁ , 3DV ₁ , 3DW ₁ of the second AC interphase reactor 3D are connected to the primary winding of the first isolation transformer 2A, and the windings 3DU ₂ , 3DV ₂ , 3DW ₂ are the second The winding 3FU ₁ , 3FV ₁ , 3FW ₁ of the third AC interphase reactor 3E is connected to the primary winding of the third insulation transformer 2C and is connected to the primary winding of the insulation transformer 2B. Lines 3FU ₂ , 3FV ₂ , 3FW ₂ are connected to the primary winding of the fourth isolation transformer 2D.
Further, the secondary windings of the first to fourth two-winding isolation transformers 2A to 2D are connected to the AC circuits of the first to fourth three-phase bridge rectifiers 1A to 1D, respectively, and these DC circuits are connected in parallel. It is connected to the.

According to this embodiment, the input phase of the three-phase bridge rectifier 1D is obtained by the action of the first to third AC interphase reactors 3B, 3D, 3F and the first to fourth two-winding insulation transformers 2A to 2D. Assuming the reference phase, since the effective values of the input currents of the three-phase bridge rectifiers 1A to 1D are equal and the input phases are 45 degrees, 15 degrees, 30 degrees, and 0 degrees, this rectifier circuit operates as a parallel 24-pulse rectifier circuit. To do.
In this embodiment, all the AC interphase reactors 3B, 3D, 3F can be connected to the primary side of the isolation transformers 2A to 2D, that is, the high voltage side in the intended use of the present invention to reduce the current. Compared with the embodiment, the configuration of the windings of the AC interphase reactors 3D and 3F can be simplified, and thus there is an effect that the AC interphase reactor and the entire circuit can be further reduced in size and cost.

1 is a circuit diagram showing a first embodiment of the present invention. It is a phasor figure for demonstrating the effect | action of the reactor between alternating current phases in 1st Embodiment. It is a circuit diagram which shows 2nd Embodiment of this invention. It is a circuit diagram which shows 3rd Embodiment of this invention. It is a circuit diagram which shows 4th Embodiment of this invention. It is a circuit diagram of the prior art described in the nonpatent literature 1. It is a circuit diagram of the prior art described in the nonpatent literature 1. It is a circuit diagram of the prior art described in the nonpatent literature 2. It is a circuit diagram of the prior art described in Patent Document 1. FIG. 6 is a circuit diagram of a conventional technique described in Non-Patent Document 3.

Explanation of symbols

1A, 1B, 1C, 1D: Three-phase bridge rectifiers 2, 2 ', 2A, 2B, 2C, 2D: Insulation transformers 3A, 3B, 3C, 3D, 3E, 3F: Reactor between AC phases 4: Smoothing capacitors U, V , W: 3-phase input terminal P, N: DC output terminal

Claims (4)

Of the first and second three-phase AC power supplies that are insulated from each other and have an output voltage having a phase difference of approximately 30 degrees,
The output of the first three-phase AC power supply is input to the input terminal group of the second interphase reactor via the first input terminal group and the output terminal group of the first interphase reactor,
The output of the second three-phase AC power supply is input to the input terminal group of the third interphase reactor via the second input terminal group and the output terminal group of the first interphase reactor,
The first output terminal group of the second interphase reactor is connected to the input terminal group of the first three-phase rectifier,
A second output terminal group of the second interphase reactor is connected to an input terminal group of the second three-phase rectifier;
The first output terminal group of the third interphase reactor is connected to the input terminal group of the third three-phase rectifier,
The second output terminal group of the third interphase reactor is connected to the input terminal group of the fourth three-phase rectifier,
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is
When the effective values of the current flowing through the first input terminal group and the output terminal group are equal to the current flowing through the second input terminal group and the output terminal group, and the phase difference between these currents is approximately 30 degrees The windings are magnetically coupled to each other so that the magnetomotive force acting on the reactor core is almost zero,
The second and third interphase reactors are
When the effective value of the current flowing out from the first output terminal group of each interphase reactor is equal to the effective value of the current flowing out from the second output terminal group, and the phase difference between these currents is approximately 15 degrees, A parallel 24-pulse rectifier circuit, wherein a plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the core of the reactor is substantially zero. A three-phase AC power supply is input to the input terminal of the first three-phase isolation transformer via the first winding group of the first interphase reactor, and the second winding group of the first interphase reactor. Is connected to the input terminal of the second three-phase isolation transformer via
The output terminal of the first three-phase isolation transformer is connected to the input terminal group of the first three-phase rectifier through the input terminal group of the second interphase reactor and the first output terminal group,
The output terminal of the first three-phase isolation transformer is connected to the input terminal group of the second three-phase rectifier through the input terminal group and the second output terminal group of the second interphase reactor,
The output terminal of the second three-phase isolation transformer is connected to the input terminal group of the third three-phase rectifier via the input terminal group of the third interphase reactor and the first output terminal group,
The output terminal of the second three-phase isolation transformer is connected to the input terminal group of the fourth three-phase rectifier through the input terminal group and the second output terminal group of the third interphase reactor,
The phase difference between the output voltage of the first three-phase isolation transformer and the output voltage of the second three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
In the first interphase reactor, the number of turns of the first winding group and the second winding group is equal, and the windings wound on the same iron core are magnetically coupled with opposite polarities.
The second and third interphase reactors are
When the effective value of the current flowing out from the first output terminal group of each interphase reactor and the current flowing out from the second output terminal group are equal and the phase difference between these currents is approximately 15 degrees, A parallel 24-pulse rectifier circuit characterized in that a plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the core of the reactor is substantially zero. The three-phase AC power source is connected to the input terminal of the first three-phase isolation transformer via the input terminal group and the first output terminal group of the first interphase reactor, and the input terminal of the first interphase reactor Connected to the input terminal of the second three-phase isolation transformer via the group and the second output terminal group,
The first output terminal of the first three-phase isolation transformer is connected to the input terminal group of the first three-phase rectifier through the first input terminal group and the output terminal group of the second interphase reactor,
The second output terminal of the first three-phase isolation transformer is connected to the input terminal group of the second three-phase rectifier through the second input terminal group and the output terminal group of the second interphase reactor,
The first output terminal of the second three-phase isolation transformer is connected to the input terminal group of the third three-phase rectifier through the first input terminal group and the output terminal group of the third interphase reactor,
The second output terminal of the second three-phase isolation transformer is connected to the input terminal group of the fourth three-phase rectifier through the second input terminal group and the output terminal group of the third interphase reactor,
The phase difference between the voltage at the first output terminal and the voltage at the second output terminal of the first three-phase isolation transformer is approximately 30 degrees;
The phase difference between the voltage at the first output terminal and the voltage at the second output terminal of the second three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is
When the effective value of the current flowing out from the first output terminal group is equal to the current flowing out from the second output terminal group and the phase difference between these currents is about 15 degrees, the current of the reactor core The windings are magnetically coupled to each other so that the acting magnetomotive force is almost zero,
The second and third interphase reactors are
When the effective value of the current flowing through the first input terminal group and the output terminal group is equal to the current flowing through the second input terminal group and the output terminal group, and the phase difference between these currents is approximately 30 degrees A parallel 24-pulse rectifier circuit characterized in that a plurality of windings are magnetically coupled to each other so that the magnetomotive force acting on the core of the reactor is substantially zero. A three-phase AC power source is connected to the input terminal group of the second interphase reactor via the input terminal group and the first output terminal group of the first interphase reactor, and the input terminal group of the first interphase reactor and It is connected to the input terminal group of the third interphase reactor via the second output terminal group,
The first output terminal group of the second interphase reactor is connected to the input terminal group of the first three-phase rectifier through the first three-phase isolation transformer,
A second output terminal group of the second interphase reactor is connected to an input terminal group of the second three-phase rectifier through a second three-phase isolation transformer;
The first output terminal group of the third interphase reactor is connected to the input terminal group of the third three-phase rectifier through the third three-phase isolation transformer,
A second output terminal group of the third interphase reactor is connected to an input terminal group of the fourth three-phase rectifier through a fourth three-phase isolation transformer;
The phase difference between the output voltage of the first three-phase isolation transformer and the output voltage of the second three-phase isolation transformer is approximately 30 degrees;
The phase difference between the output voltage of the third three-phase isolation transformer and the output voltage of the fourth three-phase isolation transformer is approximately 30 degrees;
In the rectifier circuit in which the DC terminals of the first to fourth three-phase rectifiers are connected directly or in parallel via a DC reactor,
The first interphase reactor is:
When the effective value of the current flowing out from the first output terminal group is equal to the current flowing out from the second output terminal group and the phase difference between these currents is about 15 degrees, the current of the reactor core The windings are magnetically coupled to each other so that the acting magnetomotive force is almost zero,
The second and third interphase reactors have the same number of turns of the first winding group connected to the first output terminal group and the second winding group connected to the second output terminal group. A parallel 24-pulse rectifier circuit, wherein windings wound around the same iron core are magnetically coupled with opposite polarities.

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