| 摘要 |
An overmodulation PWM control unit (200) includes a voltage amplitude calculating unit (245) for calculating a voltage command amplitude VA of an original voltage command (Vd#, Vq#) based on current feedback control, a voltage amplitude correcting unit (270) for performing linear compensation on the voltage command amplitude so that a fundamental amplitude of a pulse width modulation voltage provided from an inverter (14) may match the original voltage command amplitude (VA), and a harmonic determining unit (300) for determining presence or absence of superimposition of a three-order harmonic component on a phase voltage command. The harmonic determining unit (300) performs switching between presence and absence of the three-order harmonic component based on transition of the original voltage command amplitude (VA) to avoid passing through a change point where discontinuity occurs in the voltage amplitude characteristics representing a relationship between a fundamental amplitude obtained in advance for each of the cases of presence and absence of the superimposition of the three-order harmonic component and the voltage command amplitude required for achieving the fundamental amplitude.
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