Research On Permanent Magnet Motor Drive System For Electric Vehicle

With the development of China’s economic,people’s living standards have improved a lot.At the same time,the rapid growth of private car ownership has made it an indispensable part of people’s life.Although cars have brought convenient to people’s life,environment problem caused by exhaust emission also appears as well.Therefore,electric vehicles(EV)based new energy vehicles have become one of the most important developing direction in China’s automotive industry.Permanent magnet synchronous machine(PMSM)drive system,which is commonly used in EV is studied in this article.Taking the special need of driving system in EV application as a starting point,key technologies such as vector control,flux-weakening control,regenerating brakes are analyzed theoretically.Matlab/Simulink is used to justify the correctness of them.In the article,the developing history of EV,key technology of it,advantages and disadvantages of it comparing to traditional combustion engine vehicle is introduced first.This part also contains overview of the composition of electric vehicle motor drive system and the selection problem of driving motor and battery.Then,the math model od PMSM,coordinate transformation,FOC control,MTPA control,flux-weakening control and decoupling control algorithm are introduced.Regeneration braking problem is also studied under the specific application background of EV.Finally,simulation model of PMSM control system is built in Matlab/Simulink.SVPWM and several MTPA algorithms are realized.The advantage and disadvantage of different MTPA algorithm are deeply compared under variable motor parameter condition.An improved variable step searching MTPA algorithm is proposed after.Besides,flux-weakening algorithm is also included in the model and smooth transition between two operation regions is realized.