Model Predictive Control Of Permanent Magnet Synchronous Motor For Vehicle

China is rich in mineral resources.With China’s increasing research and development efforts on rare earth permanent magnet materials and the improvement of related manufacturing processes and the continuous expansion of its application range,permanent magnet synchronous motors have high efficiency,high power density And the advantages of simple structure and high efficiency,so it is widely used in aerospace,electric vehicles,CNC machine tools and electric vehicles.Permanent magnet synchronous motors for electric vehicles are affected by many factors during operation,such as external environmental interference,load changes,and time-varying system parameters,which results in unsatisfactory operating performance.Therefore,in order to improve their work efficiency and system performance,further Improve the development of related control technologies.Direct torque control is widely used because of its high robustness,low parameter sensitivity,and good dynamic control performance.However,due to the inherent problems of the hysteresis comparator,the system has large torque and flux ripple,as well as unstable switching frequency,which affects the life of the inverter.This paper mainly contains the following contents:(1)The current development status of the permanent magnet synchronous motor drive system is introduced,and the classic vector control and direct torque control schemes of permanent magnet synchronous motor and several commonly used efficiency optimization methods are described.According to the principle of space coordinate conversion,the mathematical model in the three-phase stationary coordinate system(A-B-C)of the permanent magnet synchronous motor and the motor equation in the two-phase rotating coordinate system are established.Based on traditional(Direct Torque Control,DTC)and vector control,DTC and vector control models of permanent magnet synchronous motors are built.The advantages and disadvantages of DTC and vector control are studied by simulation.At the same time,the structure and working principle of SVPWM are introduced and simulation model.(2)The basic idea,structural composition,working principle of the model predictive control and its two application methods on the permanent magnet synchronous motor are expounded.:Model predictive current control and model predictive torque control.Model predictive control solves the problems of flux linkage and large torque ripple in traditional direct torque control.Through simulation experiments and comparison with DTC,the torque amplitude fluctuation drops by about 43%,which proves the feasibility of model predictive control.Effectiveness and correctness.At the same time,in order to further reduce torque ripple,an optimized strategy for predictive torque control of permanent magnet synchronous motors based on duty cycle modulation is proposed.The duty cycle calculation formula is derived based on the torque ripple prediction,and a simulation model is built and verified.(3)A model predictive torque control method based on expanded voltage vector is proposed.By expanding the number of candidate voltage vectors in the limited control set,using two-step prediction to obtain the optimal voltage vector,reducing the steadystate torque fluctuation of the motor and reducing the switching loss of the inverter,by increasing its candidate vector,the torque and The degree of freedom of flux control is established,and a simulation model is established,and compared with the traditional MPC and duty cycle MPC,the proposed strategy torque fluctuations are reduced by 14% and 7% respectively,the speed is more stable,and the fluctuation range is 59% of MPC.It is 72% of the duty cycle MPC,which verifies the effectiveness and superiority of the proposed strategy.