Current Harmonics Suppression of Permanent Magnet Synchronous Motor Based on Repetitive Control

In permanent magnet synchronous motor (PMSM) drive systems, there are 5th, 7th, 11th, 13th and other low order current harmonics due to the non-ideal factors such as the distortion of the air-gap field and the nonlinear characteristics of the inverter. In order to suppress the current harmonics and improve the system performance, repetitive controller is employed in parallel with proportional integral (PI) controller of current loop in the synchronous rotating dq coordinate system in this paper. Repetitive control originates from the internal model principle of control theory, which has inhibitory effect on periodic disturbances. It can suppress integer harmonic of a given frequency and get high-accuracy output waveforms. This method does not need to increase any hardware, and is easy to implement. Simulations and experiments are carried out to verify the effectiveness of the proposed method for current harmonic suppression.