Analysis and Suppression Method of Motor Current Fluctuation Caused by DC-Link Voltage Ripple in PMSM Drives

The motor phase current fluctuation phenomenon in PMSM drives has been reported in recent years, but the problem has not been well solved even in many commercial motor drive products. In this paper, the Hilbert Transform is used to perform a more general analysis of the current fluctuation envelope. The relationship between the frequency of the phase current fluctuation, the frequency of the DC-link voltage ripple, and the output frequency of the inverter is explained. A suppression method based on the feedback of the amplitude of the motor stator current and a repetitive controller in parallel with the current controller is proposed. Both simulation and experimental results on a single-phase and a three-phase PMSM drive with diode rectifier input have confirmed the mathematical analysis and the effectiveness of the suppression strategy.