Permanent Magnet Synchronous Motors (PMSMs) are widely used in servo systems due to their high efficiency, high power density, high reliability, and simple structure. However, when operating at low speeds, the motor torque experiences significant ripples due to external disturbances, increased nonlinear effects in the system, and limitations in the resolution of position sensors. These torque ripples affect the system's stability during low-speed operation. This paper addresses the periodic torque ripples caused by load fluctuations, friction torque variations, cogging torque, electromagnetic torque, and inverter dead-time effects at low speeds.To suppress these torque ripples, we propose an integrated control strategy combining an Integral Proportional (IP) controller with a Quasi-Proportional Resonant (QPR) controller. Compared to traditional control schemes, this combined approach significantly enhances the suppression of torque ripples, optimizing the performance of PMSMs, especially during low-speed operations. This method reduces speed ripples by approximately 82%, thereby improving both the steady-state and dynamic performance of the servo system at low speeds.
 

Motor Drive System; Torque Ripple Suppression; Quasi-Proportional Resonant Control