Adaptive Torque Ripple Suppression Methods of Three-Phase PMSM During Single-Phase Open-Circuit Fault-Tolerant Operation

In this project, adaptive torque ripple suppression methods by utilizing resonant controllers during single phase open-circuit fault-tolerant operation of three-phase star connected Permanent Magnet Synchronous Motor (PMSM) is proposed. A zero-sequence current is supposed to be injected to maintain the post fault torque same as pre-fault torque. 

According to post-fault PMSM model, feed-forward voltage compensation can be adopted to inject the zero-sequence current and hence attenuate the post-fault speed and torque ripples in vector control framework. However, the feed-forward voltage compensation which is related to phase resistance and leakage inductance may be inaccurate due to temperature variation, etc., and hence an unexpected 2nd harmonic torque ripple still exists. 

In this paper, adaptive suppression methods of the 2nd harmonic torque are proposed: the first one constructs a novel closed current loop of zero axis and the second one modifies the controllers in dq axis current loop. These methods are based on resonant controllers which can adaptively compensate the voltage needed for the zero-sequence current injection. simulations are implemented based on a four-leg inverter, and the performance comparison between feed-forward compensation and adaptive compensation validate that the proposed methods can effectively suppress the post-fault torque and speed ripple. The proposed system is modelled and simulated in MATLAB/SIMULINK.

Keywords: Fault-tolerance, resonant controller, torque ripple suppression, three-phase PMSM.