Nonparametric Sensorless Drive Method for Open-Winding PMSM Based on Zero-Sequence Back EMF With Circulating Current Suppression

This paper proposes a novel sensorless method for open-winding (OW)-permanent magnet synchronous machine (PMSM) (OW-PMSM) with circulating current suppression. First, a zero-sequence steerable space vector pulse width modulation together with zero-sequence controller (ZSC) is implemented to suppress the circulating current existing in the OW-PMSM drive system with common dc bus. Afterward, the zero-sequence back EMF reconstructed from the output signal of the ZSC is utilized to extract the position information via synchronous phase-locked loop-based position observer. Hence, the voltage transducer and resistance network used in the conventional zero-sequence back-electromotive force-based sensorless methods can be consequently eliminated. Moreover, the proposed method requires no machine parameters, such as winding resistance, d- and q-axis inductances which are indispensable for the conventional fundamental back-EMF-based methods. The voltage disturbance components due to the resistance, inductance, and rotating cross coupling voltage drops can be avoid. Therefore, stronger robustness against the variation of machine parameters due to load or temperature variation can also be obtained. Finally, the proposed method is validated via experiments on a 3-kW OW-PMSM drive system.