A novel direct torque control method with the compensation of rotating EMF to reduce torque ripple for permanent magnet synchronous motor drives

Classical direct torque control (DTC) for permanent magnet synchronous motor (PMSM) has some drawbacks of more torque/flux ripples, and variable switching frequency. On the basis of an analysis of surface mounted PMSM, a novel DTC method combining space vector modulation (SVM) technique, a torque regulator with variable proportional coefficient, and a reference voltage generator with the compensation of rotating electromotive force (EMF) is proposed in the paper so as to solve the above problems. It is derived that the proportion coefficient of the torque regulator will change with the actual torque. And the EMF compensation principle is given. Its simulation model and experiment system were built up. The experiment results show that it has the advantages of the small current distortion, low torque ripple in full region, rapid response with changes of input and good anti-interference performance.