Research On Voltage Vector Selection Strategy Of Direct Torque Control Strategy In Permanent Magnet Synchronous Motor For New Energy Vehicle

The Direct Torque Control(DTC)technology bases on the stator flux linkage and uses the torque as the control object directly.It avoids the large amount of calculation when rotating coordinate transformation,and independent of the motor parameters.Its dynamic performance is good,the torque response time is short,and has the big development space in the traction domain.In this paper,the motor control system of new energy vehicles is studied.This paper focuses on the selection of voltage vector and its optimization method in surface permanent magnet synchronous motor(SPMSM),which has a certain significance to apply DTC technology in the new energy vehicle motor control system.Based on the principle of DTC,this paper analyzes the traditional SPMSM-DTC system realized by switch table.The irrational torque ripple is simulated and the effect of the voltage vector is not always satisfied.The view that the change of torque angle is equivalent to the change of torque is not always true.When the torque angle is large,the voltage vector of the switching table is opposite to the control requirements of the stator flux and torque,and the torque change is inconsistent with the expected,the change is consistent with the variation of the stator flux amplitude,which causes the torque ripple.The interval table of voltage vector's selection established by the analysis of the effect of the voltage vector on the stator flux and torque.A simple selection strategy of voltage vector is proposed.The selected voltage vector synthesized by space vector modulation.Simulation results show that the selection strategy of simple voltage vector can always meet the control requirements of the amplitude of stator flux and torque of the SPMSM-DTC system,weakening the unreasonable torque ripple caused by the switching table.Finally,the optimal selection of voltage vector studied by predictive control.An optimal selection strategy of voltage vector is proposed.Simulation results show that the optimal selection strategy of voltage vector can improve the accuracy and rapidity,reduce the torque and flux error,and its comprehensive control effect is better than the simple strategy of voltage vector selection.