Research On Adaptive High-efficiency Control Of Permanent Magnet Synchronous Motors For Vehicles

Permanent magnet synchronous motors are widely used in new energy vehicles because of their advantages of simple structure,light weight,small size,low noise,large power density,and high control accuracy.In the environment of energy saving,emission reduction and environmental protection,the optimization of the loss efficiency of the motor has also become a hot spot for many scholars.In this paper,the method of combining vector control and loss model control is used to improve the loss efficiency of the motor;combining the identification of the least squares parameter with the loss model of the motor,an optimal control strategy for the loss model efficiency based on the least square method is proposed.Magnetic synchronous motors realize adaptive high-efficiency control.The thesis mainly includes the following:(1)First,the generalization and development status of the permanent magnet synchronous motor are introduced,and the vector control strategy and direct torque control strategy of the permanent magnet synchronous motor drive system and several commonly used schemes for efficiency optimization of the permanent magnet synchronous motor are summarized.(2)The mathematical model of PMSM two-phase static and rotating coordinates is established,the principle of SVPWM is studied and its simulation model is built.The PMSM double closed-loop control strategy is built,and the simulation analysis based on the vector control strategy is carried out.(3)The PMSM loss model is established.According to the steady-state equation of the motor,the optimal stator excitation current when the motor loss is minimized is derived analytically.On this basis,the influence of iron loss resistance,stator resistance and flux linkage on the loss model is analyzed.The sensitivity analysis of the motor parameters provides an important reference for the optimal control strategy of the loss model based on the least square method.(4)A search method based on the loss model is proposed to avoid the motor jitter caused by the conventional search method;for the influence of the parameter change of the motor on the motor loss efficiency during the operation process,a recursive least square method(Recursive Least Square)is proposed,RLS)control strategy combining parameter identification and motor loss model.This control strategy uses RLS to identify the motor parameters online,update the loss model in real time,and enhance the robustness of the motor loss model to the parameters,thereby improving the efficiency of the motor control system.The simulation results show the correctness and effectiveness of the optimal control strategy of the loss model based on the least square method proposed in this paper.