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Multiple power conversion apparatus and multiple transformer

A power conversion device and power converter technology, which is applied to transformers, fixed transformers, output power conversion devices, etc., can solve problems such as residual high-order harmonic current, and achieve the effect of reducing high-order harmonic current.

Active Publication Date: 2011-07-13
HITACHI IND PROD LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] However, in the techniques of each patent document, when the phases are collectively shifted one by one by 60 / n degrees, in the case of a small number of stages such as n=2, there are 11th, 11th, and 11th harmonic orders that cannot be reduced. 13 or more, compared with n=3 or 4, the problem of residual low-order high-order harmonic current
In addition, when a part of several windings of each phase are combined as in Patent Document 1, there is a possibility of generating higher harmonic currents other than (6k+1), (6k-1) (k is a positive integer) order

Method used

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  • Multiple power conversion apparatus and multiple transformer
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no. 1 approach

[0020] The multiple power conversion device of this embodiment adopts a two-stage multiple system with n=2.

[0021] figure 1 Among them, the multiple power conversion device 100 includes: a multiple transformer 20 connected to a three-phase domestic power supply 1 with m=3; and six single-phase unit inverters 3a, 3b, 3c, 3d, 3e and 3f are connected to the motor 4 after three-phase connection of two single-phase unit inverters 3a and 3b, 3c and 3d, and 3e and 3f whose outputs are connected in series. Among them, two-stage single-phase unit inverters 3a and 3b whose outputs are connected in series constitute a multiple power converter, and single-phase unit inverters 3c and 3d and single-phase unit inverters 3e and 3f also constitute a multiple power converter. . That is, the multiple power conversion device 100 includes multiple transformers 20 and three sets of multiple power converters whose outputs are connected in three phases. In addition, in figure 1 Among them, the ...

no. 2 approach

[0084] Next, the second embodiment of the present invention will be described focusing on the points of difference from the first embodiment. In the first embodiment, the phases of the U, V, and W phases are advanced by 10 degrees one by one in the order of the U, V, and W phases, while in the second embodiment, the phases are delayed by 10 degrees one by one. Thus, although the calculation formula is not shown, similarly to the first embodiment, the 11th and 13th harmonic components due to the direct current voltage VDC are reduced, and as the harmonic components based on Vdc ripple, the second embodiment 13 and 15 components are generated in the middle.

[0085] Figure 5 The multiple power conversion device 110 of the present invention is the same as the first embodiment in that the phases of the secondary windings of the multiple transformers 21 are adjusted, and the single-phase unit inverters (3a and 3b, 3c and 3d , 3e and 3f), respectively have a phase difference of 6...

no. 3 approach

[0089] In the first embodiment, the case where n=2 is described in which two single-phase unit inverters are connected in series for each phase, but four single-phase unit inverters can also be connected in series for each phase. Figure 6 Among them, in the multiple power conversion device 120 according to the third embodiment of the present invention, n=4 single-phase unit inverters 31 a to 31L are multiple-connected to each of the U, V, and W phases. The multiple transformers 22 are respectively 0 degree, -15 degree, -30 degree, -45 degree (U phase), -5 degree, -20 degree, -35 degree, -50 degree according to the input phases to each single-phase inverter Degree (V phase), -10 degree, -25 degree, -40 degree, -55 degree (W phase), adjust the secondary winding phase.

[0090] Additionally, in addition to Figure 6 In addition, as long as the input to the four single-phase unit inverters (31a-31d, 31e-31h, 31I-31L) of each phase has a phase difference that lags behind or leads...

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Abstract

A multiple power conversion apparatus, having a multiple transformer (20) that distributes m phase alternating current input to an initial winding to (m*n) secondary windings; a m groups of multiple power converters. The multiple power converters are formed by connecting n level single phase inverters (3a to 3f) that convert alternating current induced by each secondary winding to that of variable voltage or variable frequency in series; the secondary windings of the multiple transformer (20) has a phase difference with 60 / n degrees among n level single phase inverters (3a to 3f) corresponding to output in same phase and a phase difference with 60 / (n*m) degrees among m*n single unit inverters corresponding to all m phase. Therefore, high order harmonic current in lower order can be reduced.

Description

technical field [0001] The present invention relates to a multiple power conversion device in which multiple single-phase cell inverters are connected in series, and multiple transformers used therein. Background technique [0002] In variable-speed operation of a high-voltage (for example, 3 kV or higher) motor, multiple power conversion devices in which single-phase unit inverters are connected in series are often used in order to increase the capacity of the inverter and improve the output waveform. This multiple power conversion device uses a multiple transformer (multiple transformer) that outputs multiple three-phase AC voltages with different phases from a three-phase AC power supply. For example, in Patent Document 1, it is proposed that one of each U, V, and W phase The secondary windings are shifted by 20 degrees one by one, and the phases of the remaining six secondary windings are shifted by 10 degrees one by one. Thus, the combination of 18-pulse rectification ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/497H02M1/12H01F27/28H01F30/04
Inventor 永田浩一郎冈松茂俊片山敏男
Owner HITACHI IND PROD LTD