Expanding the Application Speed Range of Torque Ripple Suppression Control for PMSMs Using All-Pass Filters with Complex Coefficients

This paper proposes a novel torque ripple suppression control that uses an all-pass filter, expanding its application range to include medium to high rotational speeds. In conventional torque ripple suppression methods, a q-axis compensation current is generated to suppress the torque ripple. This current is superimposed onto the q-axis current command. The resulting q-axis current is PI-controlled. Therefore, the effectiveness of torque ripple suppression depends on the bandwidth of the PI controller. At medium to high rotational speeds, limited bandwidth of the controller impairs its ability to respond effectively, resulting in diminished suppression performance. Accordingly, this study focuses on the phase delay of the current control system and the proposed method compensates it using an all-pass filter. The simulation and experimental results indicate that the sixth-order torque ripple can be effectively suppressed by the proposed method in medium to high-speed ranges.