JP2023019118A - Power conversion device - Google Patents

Abstract

To allow generation of DC power without using an AC/DC converter by converting three-phase power into multi-phase power.SOLUTION: A multi-phase transformer 3 comprises: a first winding 11 constituting a primary side winding L1; and windings generating four different three phases of second to fifth windings 12 to 15 constituting a secondary side winding L2, wherein all the windings are constituted by being wound around a common iron core 8, all of the second to fifth windings 12 to 15 are star-connected, the third winding 13 is constituted by being wound around the iron core so that polarity is inverted to the second winding 12 with the number of windings of 0.73 times of the second winding 12, and connecting neutral points of the second winding 12 and the third winding 13, the fourth winding 14 and the fifth winding 15 are generated by branching from a common predetermined part in the middle of the second winding 12, and each of the second to fifth windings 12 to 15 outputs three-phase power of different phases, and outputs multi-phase AC voltage.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power converter that converts high-voltage AC power into low-voltage AC power and then generates DC power.

When generating DC power from three-phase AC power, a configuration in which DC is generated by an AC/DC converter is widely adopted. For example, in Patent Document 1, a direct current is generated using a converter circuit using IGBTs.
There is also a configuration that uses a multiphase transformer as a configuration that does not use an AC/DC converter. For example, in Patent Document 2, a 6-phase transformer having a star-connected winding and a delta-connected winding on the secondary side is used to full-wave rectify the generated 6-phase voltage to generate DC power. bottom.

JP 2017-163839 A JP 2008-295155 A

However, when an AC/DC converter is used to generate a direct current, there is a problem that high-frequency switching noise is generated, which adversely affects surrounding electronic equipment and communication equipment. In addition, the converter circuit requires a semiconductor element with a high withstand voltage, which is costly and troublesome to maintain.
In addition, the configuration using a multiphase transformer does not generate high-frequency noise, but since each phase has independent windings, the core cannot be made smaller, and the transformer becomes large.

Therefore, in view of such problems, the present invention provides a compact multiphase transformer that can generate DC power without using an AC/DC converter by converting three-phase power into multiphase power. It is an object of the present invention to provide a power converter equipped with

In order to solve the above problems, the invention of claim 1 converts three-phase power to polyphase AC power using a polyphase transformer, and uses a full-wave rectifier circuit for the converted polyphase AC power. a power conversion device for converting into DC power, wherein the multi-phase transformer includes a first winding that constitutes the primary side winding and second to fifth windings that constitute the secondary side winding. a winding for generating four different three-phase phases, all the windings are wound around a common iron core, the second to fifth windings are all star-connected, and the third winding is The wire is wound on the core such that the polarity is reversed with respect to the second winding at 0.73 times the number of turns of the second winding, and the neutral points of the second and third windings are The fourth winding and the fifth winding are generated by branching from a predetermined common part in the middle of the second winding, and each of the second to fifth windings has three different phases. It is characterized by outputting electric power and outputting multi-phase AC voltage.
According to this configuration, multiphase AC power is generated and converted to DC by a full-wave rectifier circuit to generate DC power. Therefore, it is possible to generate DC with small ripples, and an AC/DC converter that performs switching operation at high frequencies is used. It is possible to generate stable DC power without
In addition, among the four windings that make up the secondary side, the third winding is 0.73 times the second winding, and the fourth and fifth windings are the second winding. Since it is formed by branching from the middle, the number of turns can be reduced compared to winding each phase independently, and the size of the multiphase transformer can be reduced. As a result, the power converter can be made smaller.

The invention according to claim 2 is the structure according to claim 1, wherein the fourth winding and the fifth winding are formed by branching from the second winding at a position 51.8% from the neutral point, and the number of turns is is 41.4% of the second winding, and the R-phase winding of the fourth winding is branched from the S-phase winding of the second winding to form a common leg with the R-phase winding of the second winding. and the S-phase winding of the fourth winding is branched from the T-phase winding of the second winding and wound on the common leg with the S-phase winding of the second winding, and the fourth winding The T-phase winding of the line is branched from the R-phase winding of the second winding and wound on a common leg with the T-phase of the second winding, and the R-phase winding of the fifth winding is: Branched from the T-phase winding of the second winding and wound on the common leg with the R-phase of the second winding, the S-phase winding of the fifth winding is connected to the R-phase winding of the second winding. The T-phase winding of the fifth winding is branched off from the S-phase winding of the second winding and wound on a common leg with the S-phase winding of the second winding, and the T-phase winding of the fifth winding is branched off from the second winding. It is characterized in that it is wound on a common leg with the T-phase of the winding.
According to this configuration, the number of turns of the fourth winding and the fifth winding is 41.4% of the number of the second winding, so the number of turns is small and the multiphase transformer can be made compact.

According to the present invention, multiphase AC power is generated and converted to DC by a full-wave rectifier circuit to generate DC power. Therefore, an AC/DC converter that can generate DC with small ripples and performs switching operation at high frequencies is used. It is possible to generate stable DC power without
In addition, among the four windings that make up the secondary side, the third winding is 0.73 times the second winding, and the fourth and fifth windings are the second winding. Since it is formed by branching from the middle, the number of turns can be reduced compared to winding each phase independently, and the size of the multiphase transformer can be reduced. As a result, the power converter can be made smaller.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows an example of the power converter device which concerns on this invention. 1 is a configuration diagram of a polyphase transformer; FIG. FIG. 3 is a vector explanatory diagram of the polyphase transformer shown in FIG. 2; FIG. 3 is a diagram for explaining phases on the secondary side of the polyphase transformer shown in FIG. 2; 5 is an explanatory diagram showing how the output between R1 and T1 of the second winding of the secondary winding shown in FIG. 4 is applied to the load; FIG. 5 is an explanatory diagram showing how an output between the R1 terminal of the second winding and the R4 terminal of the fifth winding of the secondary windings shown in FIG. 4 is applied to the load; FIG. 5 is an explanatory diagram showing how an output between the R1 terminal of the second winding and the R2 terminal of the third winding of the secondary windings shown in FIG. 4 is applied to a load; FIG. FIG. 3 is a vector explanatory diagram showing positions from which third to fifth windings of the polyphase transformer shown in FIG. 2 are drawn;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a power converter according to the present invention. It shows the configuration for conversion to
Specifically, a 12-phase transformer 3a is used as the polyphase transformer 3 to output 12-phase voltage, and a rectifier circuit 4 having four 3-phase full-wave rectifier circuits generates a set of DC outputs. showing configuration.

2 to 8 are explanatory diagrams showing a specific configuration of the 12-phase transformer 3a. Hereinafter, the 12-phase transformer 3a will be specifically described with reference to these figures.
FIG. 2 shows a block diagram. As shown in FIG. 2, the 12-phase transformer 3a includes a first winding 11 forming a primary winding L1, and four windings (a second winding 12, a secondary winding L2) forming a secondary winding L2. It has three windings 13, a fourth winding 14 and a fifth winding 15).
Each winding has three windings (11a-11c, 12a-12c, 13a-13c, 14a-14c, 15a-15c) corresponding to the input three-phase power.

The first winding 11 may be delta-connected or star-connected, but the case of star-connection is shown here. High-voltage three-phase AC power is connected to three terminals (Rin, Sin, Tin).
The second to fifth windings 12, 13, 14, 15 are all star-connected (however, as will be described later, the fourth winding 14 and the fifth winding 15 are completely star-connected). Nana). Hereinafter, the three phases will be described as the R phase, the S phase, and the T phase.

The secondary side of the 12-phase transformer 3a includes output terminals R1, S1 and T1 of the second winding 12, output terminals R2, S2 and T2 of the third winding 13, and output terminals R3 and S3 of the fourth winding 14. , T3 and output terminals R4, S4, T4 of the fifth winding 15, providing a total of 12 terminals.
The star-connected neutral points Q of the second winding 12 and the third winding 13 are connected to each other, and the third winding 13 is wound around the iron core 8 so that the polarity of the second winding 12 is reversed. , and the number of turns is 0.73 times that of the second winding.
Further, the fourth winding 14 and the fifth winding 15 are formed by branching from the same point in the middle of the second winding 12, and the fourth winding 14 and the fifth winding 15 are formed by branching from the second winding. The neutral point Q of 12 is also used.

The fourth winding 14 and the fifth winding 15 are specifically wound around the iron core 8 as follows. In the fourth winding, the T-phase winding 14a is branched out from the middle of the R-phase winding 12a of the second winding 12 and wound around the leg core 8c common to the primary side T-phase. there is The tip is the output terminal T3.
The R-phase winding 14b is branched out from the middle of the S-phase winding 12b of the second winding 12 and wound around the leg core 8a common to the R-phase of the first winding 11 . The tip is the output terminal R3.
The S-phase winding 14c is branched out from the middle of the T-phase winding 12c of the second winding 12 and wound around the leg iron core 8b common to the primary side S-phase. The tip is the output terminal S3.

In the fifth winding 15, the S-phase winding 15a is branched from the middle of the R-phase winding 12a of the second winding 12, which is the same part as the fourth winding 14, and is drawn out. It is wound around the leg iron core 8c common to the S phase. The tip is the output terminal S4.
The T-phase winding 15b is branched out from the middle of the S-phase winding 12b of the second winding 12, which is the same part as the fourth winding 14, and is a common leg with the T-phase of the first winding 11. It is wound around the iron core 8c. The tip is the output terminal T4.
The R-phase winding 15c is branched out from the middle of the T-phase winding 12c of the second winding 12, which is the same part as the fourth winding 14, and is connected to the R-phase of the first winding 11. It is wound around the core 8a. The tip is the output terminal R4.

FIG. 3 is a vector explanatory diagram of individual windings of the secondary winding L2, showing each phase with reference to the R1 phase of the second winding 12. As shown in FIG. As shown in FIG. 3, the three-phase windings 12a, 12b, and 12c of the second winding 12 output voltages having a phase difference of 120 degrees in the same manner as the input three-phase power to the output terminals R1 and S1. , T1.
The phases of the windings 13a, 13b, 13c of the third winding 13 exhibit opposite polarities with respect to the second winding 12 as described above, and the phases of the output terminals R2, S2, T2 are the phases of the second winding 13. It has a phase difference of 180 degrees with respect to each phase of R1, S1 and T1 of the winding 12. FIG. Note that the number of turns of the third winding 13 is 0.73 times (√3−1 times) that of the second winding 12 .

The phases of the output terminals R3, S3, T3 of the windings 14a, 14b, 14c drawn from the second winding 12 of the fourth winding 14 generate voltages of the same phase as those of the third winding 13. do. Further, the phases of the output terminals R4, S4, T4 of the windings 15a, 15b, 15c drawn from the second winding 12 of the fifth winding 15 are the same as those of the fourth winding 14. A voltage having the same phase as that of the corresponding output terminals R2, S2, and T2 of each phase is generated.

FIG. 4 is a phase explanatory diagram of the secondary side, showing the output phases of the third winding 13, the fourth winding 14 and the fifth winding 15 with the phase of the R1 terminal of the second winding 12 as a reference.
As shown in FIG. 4, the voltage absolute value between the R1 terminal of the second winding 12 and the R4 terminal of the fifth winding 15 is The values are equal and the phase is delayed by 15 degrees. Also, the voltage absolute values between the R1 terminal of the second winding 12 and the R2 terminal of the third winding 13 are equal, and the phases are delayed by 30 degrees. Furthermore, the absolute values of the voltages between the R1 terminal of the second winding 12 and the S3 terminal of the fourth winding 14 are equal and the phases are delayed by 45 degrees.

5 to 7 are explanatory diagrams showing how the specific phase-to-phase voltage shown in FIG. is applied to the load 6.
FIG. 5 shows how the output across the R1-T1 terminals of the second winding 12 is applied to the load 6, and FIG. 7 shows how the output is applied to the load 6, and FIG. 7 shows how the output between the R1 terminal of the second winding 12 and the R2 terminal of the third winding 13 is applied to the load 6. FIG.
In this manner, phase-to-phase voltages having equal absolute values are rectified and applied to the load 6 .

The relationship between the phases is such that the output phases of the third winding 13, the fourth winding 14, and the fifth winding 15 with respect to the phase of the S1 terminal of the second winding 12, and the T1 of the second winding 12 The output phases of the third winding 13, the fourth winding 14, and the fifth winding 15 with respect to the terminal phase are the same, and phase-to-phase voltages with equal absolute values are generated and applied to the load 6. FIG.

FIG. 8 is a vector explanatory diagram showing the positions at which the fourth winding 14 and the fifth winding 15 are pulled out from the second winding 12. Hereinafter, with reference to this vector diagram, the fourth winding 14 and the fifth winding The position X for pulling out 15 will be specifically described.
Assuming that the voltage across the R1-R2 terminals shown in FIG. 8 is 200V, the voltage (A+B) across the R1-R4 terminals is also 200V.
and the voltage E1 between Q and R1 is the output voltage of the second winding 12,
E1=200/√3=115.4V.
And voltage A = voltage B/tan15°
Therefore, considering voltage A = 200 - voltage B,
Voltage A=200/(1+tan15°)=157.73V
becomes,
Voltage B = 200 - Voltage A = 200 - 157.73 = 42.27V
becomes.

Here, in order to obtain the pull-out position Z of the 4th and 5th windings, if the X point where (R1-X)×cos15°=A is set between Q and R2,
Voltage between R1-X points=A/cos15°=157.73/0.966=163.3V
Also, since the voltage between Z and R4 is equal to the voltage between Q and X,
Q-X voltage = (R1-X voltage) - (R1-Q voltage)
= 163.3 - 115.46 = 47.83V
becomes. And this is also the voltage across Z-R4 (the voltage of the fifth winding 15) E3.

Also, (voltage between R1-X)×sin15°×√2=voltage between X-R4,
Voltage across QZ=Voltage across X-R4=163.3×0.259×1.41=59.7V.
Therefore, the drawing position Z of the fourth and fifth windings is
(Voltage between Q-Z)/(Voltage between Q-T1) = 59.7/115.4 = 0.518
becomes.
That is, the pull-out position is 51.8% from the neutral point Q.

Looking at the turns ratio between the second winding 12 and the fourth winding 14 (the turns ratio between the second winding 12 and the fifth winding 15),
E3/E1=47.8/115.5=0.414
As a result, the fourth winding 14 and the fifth winding 15 are 41.4% of the second winding 12 .

From these results, looking at the turns ratio of each winding on the secondary side,
2nd winding: 3rd winding: 4th winding: 5th winding = 1:0.73:0.41:0.41
becomes.
The voltage between Q and R2=200-(voltage between R1-Q)=200-115.4=84.54V.

In this way, since multiphase AC power is generated and converted to DC by a full-wave rectifier circuit to generate DC power, it is possible to generate DC with small ripples and use an AC/DC converter that performs switching operation at high frequencies. It is possible to generate stable DC power without
In addition, among the four windings forming the secondary side, the third winding 13 is 0.73 times the second winding, and the fourth winding 14 and the fifth winding 15 are the second winding. Since it is formed by branching from the middle of the winding 12, the number of windings can be reduced compared to winding each phase independently, and the size of the multiphase transformer can be reduced. As a result, the power converter can be made smaller.
Specifically, since the number of turns of the fourth winding 14 and the fifth winding 15 is 41.4% of the number of turns of the second winding 12, the number of turns is small and the multiphase transformer can be made compact.

In the above embodiment, the voltage between the R1 terminal of the second winding and the R2 terminal of the third winding is described as 200 V, but the generated voltage is arbitrary and the output voltage can be changed according to the load form. is.

DESCRIPTION OF SYMBOLS 1... Power converter, 3... Polyphase transformer, 3a... 12-phase transformer, 4... Rectifier circuit, 8... Iron core, 11... First winding, 12... Second winding, 13... 3rd winding, 14... 4th winding, 15... 5th winding, L1... primary side winding, L2... secondary side winding

Claims (2)

A power conversion device that converts three-phase power to multiphase AC power using a polyphase transformer and converts the converted polyphase AC power to DC power using a full-wave rectifier circuit,
The multiphase transformer includes a first winding that constitutes the primary winding and second to fifth windings that constitute the secondary winding, which generate four different three-phase phases. and all the windings are wound on a common core,
The second to fifth windings are all star-connected,
The third winding is wound around the iron core such that the number of turns of the third winding is 0.73 times that of the second winding and the polarity is reversed with respect to the second winding. The neutral points of the three windings are connected to each other,
The fourth winding and the fifth winding are generated by branching from a predetermined common part in the middle of the second winding,
A power converter, wherein each of said second to fifth windings outputs three-phase power with different phases and outputs multi-phase AC voltage. The fourth winding and the fifth winding are formed by branching from the second winding at a position 51.8% from the neutral point, and the number of turns is 41.4% of the second winding,
The R-phase winding of the fourth winding is branched from the S-phase winding of the second winding and wound on a common leg with the R-phase of the second winding,
The S-phase winding of the fourth winding is branched from the T-phase winding of the second winding and wound on a common leg with the S-phase of the second winding,
The T-phase winding of the fourth winding is branched from the R-phase winding of the second winding and wound on a common leg with the T-phase of the second winding,
The R-phase winding of the fifth winding is branched from the T-phase winding of the second winding and wound on a common leg with the R-phase of the second winding,
The S-phase winding of the fifth winding is branched from the R-phase winding of the second winding and wound on a common leg with the S-phase of the second winding,
The T-phase winding of the fifth winding is branched from the S-phase winding of the second winding and wound around a common leg with the T-phase winding of the second winding. The power converter according to claim 1.

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