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-module permanent magnet synchronous motor (PMSM) drive systems are receiving increasing attention in wheel motor applications with high-reliability requirements. The torque ripple introduced by pulsewidth modulated voltage excitation, which is difficult to be eliminated by the current loop design, seriously affects the system performance. An adaptive optimal carrier phase shift method is designed in this article. Compared with the traditional average carrier phase shift method, the proposed method achieves optimal suppression of torque sideband harmonics even in subhealth submodule derating operation. Especially, a novel mathematical model of the torque sideband harmonics is developed for the
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-module PMSM drive system. Then, two carrier phase shift methods are designed to optimize the carrier phase by combining structural characteristics to reduce the dimensionality of the optimization search. Furthermore, two optimization objectives are set: minimizing the peak value of the torque sideband harmonics and the amplitude of the torque sideband harmonics at a specific frequency. Based on the designed parallel grid search method, the best solution can be obtained with less computational stress. Finally, the proposed method's torque sideband harmonic suppression performance based on the optimal objective at different fundamental frequencies and output current is verified in a 5.6 kW four-module in-wheel motor drive system.
