Smooth Speed Control for Low-Speed High-Torque Permanent-Magnet Synchronous Motor Using Proportional-Integral-Resonant Controller

This paper proposes a speed and current proportional-integral-resonant (PIR) control strategy to realize smooth speed control of the low-speed high-torque permanent-magnet synchronous motor (PMSM) drive system by minimizing the periodic torque ripples. Some non-ideal factors causing periodic torque ripples, such as harmonics of rotor flux, cogging torque, current measurement errors, and dead time of inverter, are mathematically modeled, and their effects on current and speed control are analyzed, according to their locations in the system. Stability analysis is carried out, considering the delays caused by current loop and speed measurement as they may make the whole system unstable under the proposed PIR control strategy, and the optimal phase adjustment parameters for resonant item to keep the system stable are then obtained through theoretical analysis and numerical simulations. Finally, experimental results achieved on a 10-kW setup prove that the proposed strategy effectively minimizes the periodic speed ripples of PMSM drive.