An Effective Compensation Technique for Speed Smoothness at Low-Speed Operation of PMSM Drives

This paper proposes a simple and effective method to reduce speed ripples of permanent magnet synchronous machines (PMSMs) under low-speed working conditions. The treated issue is related to the periodic torque ripples, which induce speed oscillations that deteriorate the drive performance. The main idea of the proposed method is to modify a conventional PMSM controller by superposing an appropriate compensation signal to the quadratic-current reference. The proposed approach allows the reduction of speed ripples at low speed through a simple compensation signal and does not require a hard calculation cost. A theoretical analysis is presented, and both simulation and experimental results are presented to validate the proposed compensation method.