Torque Ripple Reduction for BLDC Permanent Magnet Motor Drive using DC-link Voltage and Current Modulation

Abstract

T This paper proposes a torque ripple reduction for brushless DC (BLDC) permanent magnetic (PM) motor drive based on the DC-link voltage pulse amplitude modulation (PAM). BLDC drives have the better inverter efficiency and requires low position sensing resolution. However, both freewheeling current during the diode conduction and discontinuous motor phase current cause high torque ripples. These drawbacks limit the BLDC drive on some applications where noises are primarily concerned. In this paper, a front-end DC/DC converter is added to improve the BLDC reflected torque ripples. On the basis, the DC bus voltage is modulated during diode conduction while the DC current is dynamically manipulated every BLDC commutation period. The proposed torque ripple compensation of BLDC drive is verified by both simulation and experiment on a 320W PM motor. According to experimental results, around 50% torque ripple reduction is demonstrated using the proposed BLDC drive with DC voltage modulation.