A new direct torque controller to reduce torque ripple for permanent magnet synchronous motor drives

The analysis of PMSMs shows that electromagnetic torque is proportional to the angle between the stator and rotor flux linkages and therefore fast torque response can be obtained by increasing the rotating speed of the stator flux linkage as fast as possible. The implementation of DTC in PMSM drives is discussed. A new DTC controller combining space vector modulation (SVM) technique, a torque regulator with variable proportional coefficient and a new reference voltage generator using rotor rotating speed is proposed in the paper. It is derived that the proportion coefficient of the torque regulator will change with the actual torque. The new controller is not dependent on the motor parameters except the stator resistance which affects only the low speed performance of the drive and can be compensated. 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.