This paper proposes a simple control method for improving direct torque control (DTC) of permanent-magnet synchronous motor (PMSM). Although conventional torque regulator minimizes torque ripples and fixes switching frequency, it has a slow torque dynamics especially in low-speed region. This is due to the utilization of small voltage vectors during torque increment. The small voltage vectors have a small duty-cycle, which is very useful in torque ripple reduction during steady-state operation of the PMSM. However, these small voltage vectors are short compared to large voltage vectors in shorten the settling-time during dynamic operation of the PMSM especially in low-speed region. Therefore, a proposed torque regulator is used during transient-state operation of PMSM with large duty-cycle to achieve fast-dynamic response, while maintaining the conventional torque regulator merits in minimizing torque ripples during steady-state operation. Simulation results are presented to prove the effectiveness of proposed method.
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20194030202370, No. 20206910100160).