Research On Driving System Of Permanent Magnet Synchronous Motor Used For New Energy Vechicles

Nowadays,the problems of energy crisis and environmental pollution make the new energy vehicles been rapidly developed.Permanent magnet synchronous motor has the advantages of high running efficiency,high torque density,wide range of constant power speed range and high speed operation stability.It has been widely used in the field of new energy vehicles.Motor drive control system is one of the key parts of new energy vehicles,which is of great significance to study.The main work of this paper is as the following:Firstly,the paper analyzes the development status and trends of new energy vehicle drive system.The permanent magnet synchronous motor is selected as the object.Then,the corresponding mathematical model of permanent magnet synchronous motor is established.Secondly,this paper analyzes the vector control strategy that is commonly used in permanent magnet synchronous motor.A new type of sliding speed controller is designed as the speed controller of the vector control system.The new sliding mode speed controller based on the new double power reaching law is proposed to improve the sliding mode speed controller.Compared with the traditional sliding mode control,it solves the problems of reaching slowly and poor performance that the traditional single power reaching law approaches has when it is far away from the sliding surface.At the same time,it solves the problem that the traditional double power law is difficult to transit the sliding mode switching point smoothly.Which improves the response speed and stability of motor speed control system.In the new energy vehicles with permanent magnet synchronous motor vector drive system,a new composite control method combining sliding mode control and flux weakening control strategy is adopted in order to increase the speed range.When the permanent magnet synchronous motor is running below the rated speed,the new sliding mode control is applied to i_d=0 vector control system.When the permanent magnet synchronous motor is running above the rated speed,the new slip mode control and the flux weakening control strategy are used together to control the torque current.In this paper,the actual operating conditions of new energy vehicles are simulated,and the low speed and high speed operation conditions of the permanent magnet synchronous motor are simulated respectively.The simulation shows that the sliding speed controller of the system improves the response speed and anti-load disturbance ability of the system,makes the system have better robustness.The new composite control method not only meets the new energy vehicles running at low speed when the output requirements of large torque conditions,but also meets the new energy vehicles running high-speed operation of the small torque operating conditions.At the same time,the high and low speed switching operation can be achieved smoothly.The proposed control method is compared with the fuzzy adaptive PI control technology.The comparison results show that the new sliding mode controller has faster response speed and smaller torque ripple,which is more adapted to the new energy vehicles operating conditions.It shows the superiority of the new double power reaching law sliding mode control strategy.