Investigation On The Predictive Direct Torque Control For Permanent Magnet Synchronous Generator

With the aggravation of the energy crisis, wind power generation as the representative of new energy gets great attention and rapid development. Direct drive permanent magnet synchronous generation system plays an important role in the variable speed constant frequency wind power generation field because of its good operation performance, high efficiency and high reliability. Direct torque control(DTC) has simple structure and provides a fast torque response and robustness against machine parameters variations, DTC for permanent magnet synchronous wind generator can effectively improve the operation and generation performance of the system. DTC for permanent magnet synchronous generator(PMSG) is deeply investigated in this paper, including theoretical analysis, simulation study and experimental verification.Mathmatical model for PMSG in the stationary reference frame and rotating coordinate system are both built first, the basic principle of DTC is presented in detail, the control performance of stator flux linkage and electromagnetic torque are analysed. Simulation study and experimental verification for the traditional DTC based on look up table were carried out. Performance improvement is done towards the inferior steady performance of DTC based on look up table, including the hysteresis comparator study, zero vector study, DTC based on discrete space vector modulation. Simulation study are carried for traditional DTC and improvement strategy, the simulation results show that the proposed strategy improves the performance of traditional DTC.Although above strategy improve the steady performance to some extent, they don’t overcome unfixed switching frequency of DTC based on look up table. So DTC based on space vector modulation(SVM) is studied in this paper, the principle is introduced in detail and then the predictive DTC based on SVM is proposed. DTC based on model predictive control is proposed in this paper, the control strategy is introduced and the system diagram is built. The simulation study and experimental verification for the above three strategy are carried out, the comparision including theory and experimental results is carried out between three strategies.