Modeling and Control for Open-Winding PMSM Under Open-Phase Fault Based on New Coordinate Transformations

In the open-winding permanent magnet synchronous motor (OW-PMSM) system fed by dual inverter with common dc bus, suitable control strategy should be adopted to suppress the torque ripple generated by the third harmonic flux and 0-axis current. However, the mathematical model will change when the motor is under open-phase fault so that the coordinate transformations and control strategy should be redesigned accordingly in order to suppress the torque ripple. In this article, the postfault OW-PMSM system is remodeled considering the third harmonic flux. Based on the postfault model, new coordinate transformations are designed to obtain a concise torque and decoupling voltage expressions for the simple and accurate control of torque. Moreover, the torque ripple is suppressed by modifying the current reference. In addition, a simple decoupling modulation is designed to directly obtain the switching signals for the dual inverter. Experimental results confirm the effectiveness of the proposed fault-tolerant control strategy.