Torque ripple reduction and fast torque response strategy of direct torque control for permanent-magnet synchronous motor

Abstract

This paper proposes a simple method direct torque control (DTC) based on space vector pulse width modulation (SVPWM) of surface-mounted permanent-magnet synchronous motors (SPMSM). The proposed DTC method calculates the optimized voltage vector using the motor parameters and the analysis of the relationship between the stator flux, torque, and stator voltage to calculate the optimized voltage vector. Thus the overshoot does not occur and the fast and accurate torque control becomes possible. The voltage vector calculation is divided into three steps. First, the magnitude of the voltage vector is calculated using the reference torque. Second, even though the motor parameters are not precise, the accurate torque control can be achieved through the compensation of the voltage vector. Last, the angle of the voltage vector is calculated through the magnitude of the voltage vector and the stator flux error. The calculated voltage vector controls the motor instantly and accurately by operating the inverter through the DTC-SVPWM method. The effectiveness of the proposed DTC method is verified through simulation. The simulation result proves that new strategies provide low torque ripple and quick dynamic performance.