Improvement and comparison of efficiency and low cost drive system based on DTC and DTC-SVM

In this paper, an optimal reference stator flux strategy is proposed to improve the drive system efficiency under direct torque control (DTC) and DTC with space vector modulation (SVM) strategies. A low cost (LC) interior permanent magnet synchronous machine (IPMSM) is introduced and tested. Based on the easily implementable loss model control (LMC), the controllable electrical losses which consist of copper loss, iron loss and permanent magnet (PM) loss have been minimized under optimal reference stator flux. The loss model takes into account the current harmonics produced by inverter. The nonlinear machine parameters are also considered. The accuracy of loss model is improved and verified by two dimensional (2D) finite element method (FEM). The steady-state and dynamic response and system efficiency of the proposed schemes (DTC with LMC and DTC-SVM with LMC) are validated and compared in experiment.