Zero-Sequence Current Suppression Strategy of Open-Winding PMSG System With Common DC Bus Based on Zero Vector Redistribution

The open-winding configuration with a common dc bus provides a zero-sequence current loop which allows the zero-sequence current flowing. With the application in permanent magnet synchronous generator (PMSG) systems, the existing zero-sequence current is inevitably caused by the common mode voltage generated by pulsewidth modulation (PWM) techniques and the third back EMF by the inherent flux harmonic component. With the mathematical modeling analysis, the zero-sequence equivalent circuit based on the PMSG system is proposed. Meanwhile, a zero-sequence current suppression controller is designed. In this paper, a zero vector redistribution PWM technique is proposed. With this technique, the dwell times of zero vectors (000) and (111) for both converters are determined. Meanwhile, it gives the zero-sequence component overmodulation analysis. Both the control method and improved PWM technique are implemented in a 1-kW open-winding PMSG experimental setup, and the experimental results are discussed.