Current control type electric force converter output current waveform improving method thereof

Abstract

Provided is a current control type electric force converter capable of improving the waveform distortion of an output current. A harmonic shifting part (4) obtains a triple-frequency harmonic voltage component (V3') obtained by shifting a triple-frequency harmonic voltage component (V3) by a prescribed time Deltat using a phase voltage waveshape (Vu) as a reference. A signal subtration part (5) obtains a subtration signal (DeltaI3) by multiplying the triple-frequency harmonic voltage component (V3') by a gain (K1), and three-phase modified current command signals (Iux - Iwx) are obtained by subtracting three-phase current command signals (Iu_ref - Iw_ref) for feedback control by the subtration signal (DeltaI3). A grid signal generating circuit (2) outputs grid signals to six semiconductorswitching elements of a three-phase inverter circuit (IV) according to the three-phase modified current command signals (Iux - Iwx).

Description

technical field [0001] The present invention relates to a current control type power converter and an output current waveform improving method of the current control type power converter for improving the distortion of the output current waveform of the converter. Background technique [0002] Japanese Unexamined Patent Publication No. 2000-224862 (Patent Document 1) discloses a conventional three-phase four-wire type voltage control type power converter. In this voltage control type power converter, a pair of capacitors connected in series are provided between a pair of DC output terminals of the DC power supply, and a connection point of the pair of capacitors is used as a neutral phase. [0003] In addition, Japanese Patent Application Laid-Open No. 2007-274825 (Patent Document 2) discloses a three-phase, four-wire voltage-controlled power converter having a reactor. , a neutral phase arm (arm) connecting two sets of semiconductor switching elements in series is provided...

AI Technical Summary

Problems solved by technology

[0006] In the former three-phase four-wire voltage control type power converter, the output current waveform will produce relatively large distortion

In addition, in the latter voltage control type power converter, although the distortion of the output current waveform is small, it is necessary to provide a neutral phase arm and perform PWM control on the neutral phase arm, and the structure becomes complicated.

Furthermore, since conventional voltage-controlled power converters control the output voltage constantly, it is difficult to positively improve the distortion of the output current waveform.

Moreover, this problem is a common problem faced by current-controlled power converters using a multi-phase inverter circuit and using the connection point of a pair of capacitors as the neutral phase.

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