Research On Control Algorithm Of Permanent Magnet Synchronous Motor For Low Speed Electric Vehicle

In recent years,eco-friendly and cost-effective low-speed electric vehicles(EV)have gradually become one of the important means of transportation in the city,its overall performance has been more and more concerned by the industry.Permanent magnet synchronous motor(PMSM)is the mainstream motor used in the drive system of low-speed electric vehicles.The performance of PMSM controller based on microcontroller is the key to the overall performance of EV.Therefore,the related algorithm research of optimizing controller performance becomes the current research hotspot.At present,the PMSM controller focuses more on the control performance of the motor at the rated speed,and its control algorithm tends to decrease when the motor is running at low speed.The dead zone effect of the inverter in the motor controller and the detection precision of the speed feedback in the speed closed-loop control are the important factors that affect the good operation of the electric vehicle in the low speed area.In view of the above problems,this paper has carried out the research on the low speed zone control algorithm applied to the low speed electric vehicle permanent magnet synchronous motor.(1)Aiming at the problem of the dead zone effect of the inverter,the vector control strategy is determined by analyzing the structure and working principle of PMSM,as well as the mathematical model under the two-phase rotating coordinate system.After analyzing the vector control principle of PMSM,the principle of voltage space vector pulse width modulation(SVPWM)technology in vector control is further analyzed,and a method of dead zone effect compensation based on time is proposed.The experimental results show that this method can effectively reduce the noise and torque ripple of PMSM.(2)In order to improve the accuracy of speed feedback in the speed control loop,a new parameter selection principle of variable parameter M/T speed measurement method is given by comparing and analyzing the error of the traditional motor speed measurement method.At the same time,the realization method on the controller system designed in this subject is given.The experimental data show that the improved speed measurement algorithm improves the control precision in the actual motor control and effectively controls the speed fluctuation of the motor when running at low speed.(3)In order to verify the proposed control algorithm,the permanent magnet synchronous motor and motor controller are assembled with the magnetic particle brake experimental platform.The main experimental contents include: dead zone compensation effect of SVPWM algorithm,improved variable parameter M/T method and vehicle field test data.Through the analysis of the experimental waveforms,data and field test results,it can be concluded that the proposed control algorithm and the designed controller system can meet the application requirements of low-speed electric vehicles.At the same time,without obviously increasing the hardware cost,the control algorithm proposed in this paper effectively improves the control accuracy of the motor,improves the fluctuation of the speed of the low-speed electric vehicle in the low-speed zone,improves the comfort of the driver,and has good application value.