A Harmonic Suppression Strategy for Improving Estimation Accuracy of Sensorless PMSM Drives Considering Non-sinusoidal Back EMFs

In this article, an harmonic suppression strategy of rotor position error utilizing synchronous reference frame filter (SRFF) is proposed to enhance sensorless control performance of permanent magnet machines (PMSMs) considering non- sinusoidal back electromotive force (EMF). SRFF strategy is proposed and integrated into sliding mode observer (SMO)- based observer to extract the fundamental wave of the back EMF before applying to the phase-locked loop. Although the LPF is incorporated into the SRFF strategy, it will not introduce phase delay and amplitude attenuation because LPF has no effects on the phase of the direct-current input signals. Therefore, the estimated accuracy of rotor position as well as the speed ripple can be improved. Finally, an experimental platform is established, and the proposed method is validated and compared with the conventional method.