Torque ripple reduction of an interior PM synchronous motor for electronic power steering

Back emf harmonics of a PM synchronous motor is one of the major sources of the torque ripples. This paper presents the torque ripple reduction method for an interior PM synchronous motor that has back emf harmonics. To reduce the torque ripples due to the back emf harmonics, the harmonics of the back emf are analyzed through FFT analysis. The compensation dq currents to cancel the torque ripples caused by the back emf harmonics are calculated from the nominal dq currents for MTPA operation proposed method is verified by the simulation and experiments.