Simple expressions for suppression of torque and speed vibrations in PMSM drives

Torque ripples exist in permanent magnet synchronous motors (PMSMs) mainly due to non-sinusoidal flux density distribution around the air-gap. These torque ripples vary periodically with rotor position and are reflected as speed ripple, which degrades the PMSM drive performance, particularly at low speeds. In this paper, a simple expression based on the harmonic compensation technique and Fourier series analysis is presented which provides appropriate current shapes to drive a PMSM with less torque ripple. Unlike the intricacy of new schemes based on adaptive control or iterative optimization methods, the proposed approach provides torque ripple minimization without any complexity and it does not need many computations for implementation. To evaluate the effects of this control system a simulation model of PMSM drive based on the MATLAB/ Simulink with detailed authentic results are presented.