Permanent Magnet Synchronous Motor Control System For Electric Vehicle

With the gradual development of China's society and economy,the quality of people's life has been increased significantly.More and more people choose the car instead of walking in their daily commutes.Although driving cars accelerated the pace of people's lives and reduced the time spent on the road,it brought more energy consumption and greater environmental pollution.People are facing the huge problems of effectively controlling the car exhaust,reducing air pollution,and improving the energy efficiency.So pure electric vehicles will be an important development direction of the entire automotive industry.Electric vehicles are driven by motors,thus whether the motors' performance are good or bad determine the driving capacity of electric vehicles.The permanent magnet synchronous motor(PMSM)control technology developed rapidly in recent years.Its high power density characteristics is the reason why more and more car manufacturers choose to use it to provide power for electric vehicles.Electric vehicle control system is core of electric vehicles.Its performance directly affect the driving experience and safety of electric vehicles.This paper presents a PMSM control system for an electric vehicle that has a 6kW PMSM.It also presents a study on the control algorithms for PMSM regarding its characteristics.We first explain the mathematical model of PMSM and the transformation between different coordinate systems.And then we explain the control theory of the PMSM,and analyze two kinds of control methods in detail,namely vector control and direct torque control.Secondly,we designed and built the hardware circuit of the PMSM control system of the electric vehicle,which mainly includes the selection of the main control chip,the power management circuit,the motor drive circuit,the communication circuit,the driver operation signal acquisition circuit and the system self feedback signal detection circuit.In the hardware circuit design section,we analyzed the motor drive which consist of bootstrap IR2010 S driver and MOSFET MXP8835 in detail.Then we illustrated the software system design and its flow chart,which mainly includes the design of the main program of the system,the collection and processing of data,the current detection and over-current protection subroutine,the judgment of the vehicle condition,the software implementation of the PWM interrupt service and the CAN bus communication.The control algorithm of PMSM is built in Matlab / Simulink.The control algorithm of PMSM is simulated according to the model,and the system parameters are adjusted by software simulation,which reduces the workload of debugging.And then we analyzed and compared the simulated result of PI-regulator based vector control method with the traditional direct torque control method.Finally,we debugged and analyzed the whole system and came to the conclusion that the designed PMSM control system has good traits like fast response,small overshoot,good dynamic performance and anti-disturbance ability and it meets the performance requirements of the electric vehicle in the actual situation.