Research On The Optimal Direct Torque Control Of Open-Winding Permanent Magnet Motor System In The Variable Voltage Condition

Direct Torque Control(DTC)widely employed in applications with high dynamic performance and high reliability requirements due to the advantages of fast dynamic response,simple control structure,less dependence on motor parameters and high robustness.In order to further improve the poor steadystate performance of torque performacne for the traditional permanent magnet synchronous motor(PMSM),this paper studied the optimal strategy of DTC for open-winding PMSM based on switching table according to the four different types of the ratio of busbar voltage amplitude for the reduction of the asymmetry of the output torque,then,the open-winding PMSM driving system with DTC method could achieve good output performance in the variable voltage conditions.Firstly,the basic principle of DTC of open-winding PMSM is briefly introduced.In the view of the changing condition of busbar voltage amplitudes,the asymmetry characteristics of torque control is analyzed for several reasonable switching table schemes,then,the optimal switching table is established for each of the four intervals of busbar voltage amplitude ratio.Based on the simulation model of the open-winding PMSM driving system with DTC method by the software MATLAB,a typical case is selected in each of the four sections of busbar voltage amplitude ratio for the analysis and comparison of the output performance before and after the switch table optimization.Then,in the assumption of the condition that the bus voltage amplitude on one side remains constant and that on the other side decreases continuously,the output performance of the proposed system based on the switching table before and after optimization is verified by the simulation results.Finally,the experimental platform of open-winding PMSM drive system based on the controller of DSP28335 and CPLD is builted,and the output performance of the system with and without the switch table optimization method is compared,it can shown that the optimal strategy proposed in this paper has obvious improvement effect on DTC steady-state performance.