Modified Direct Torque Control scheme for PMSM

This paper presents a high performance Direct Torque Control (DTC) scheme for Permanent Magnet Synchronous Motor (PMSM). This improved method can reduce the torque ripple keeping the simplicity of conventional DTC. Torque ripple is reduced by supplying adjustable switching vector in each sampling period. This method uses a duty ratio calculation technique to reduce the torque ripple. Here the duty ratio is calculated using torque error only. The torque error is independent of the width of hysteresis band. The switching pulses are generated according to switching rules and torque error. This method can also assure constant switching frequency. The effectiveness of the modified method is validated by simulation using MATLAB/SIMULINK.