Novel direct torque control of PMSM based on expected voltage space vector modulation

To minimize the ripples of the electromagnetic torque and flux linkage produced in the conventional direct torque control (DTC) system for permanent magnet synchronous motors (PMSM), this paper proposes a space vector modulation (SVM) strategy of DTC. The expected voltage was produced by SVM. PI controller in this method was used in this strategy, instead of hysteresis controller and switching table in conventional direct torque control. At the same time, a novel stator flux estimator was introduced. This scheme estimated stator flux based on stator currents and rotor position. The experimental results show that the steady state performance of the proposed DTC is improved dramatically while keeping the dynamic performance almost as same as that of the basic DTC.