PWM Strategy With Minimum Harmonic Distortion for Dual Three-Phase Permanent-Magnet Synchronous Motor Drives Operating in the Overmodulation Region

Abstract

This study presents a novel overmodulation strategy for a six-phase voltage source inverter (VSI)-fed dual three-phase permanent-magnet synchronous motor. The proposed strategy can achieve minimum harmonic injection in the overmodulation region. Four-vector space vector pulse width modulation (SVPWM) renders mathematic foundations for this given method. However, the classical four-vector SVPWM used in six-phase VSI has asymmetrical pulse width modulation waveform, which makes it difficult for hardware implementation. In this paper, the modulation algorithms in both linear and overmodulation regions have been unified and implemented with the double zero-sequence injection PWM strategy. This strategy is able to overcome the inherent shortcomings of the four-vector SVPWM, and it achieves smooth transitions from linear to overmodulation region. Simulation analysis and experimental results demonstrate the effectiveness and feasibility of the proposed strategy.