Research On Control Strategy Of Permanent Magnet Synchronous Motor For New Energy Vehicles

As a kind of high-performance motor,permanent magnet synchronous motor（PMSM）is widely used in new energy vehicles due to its advantages of light weight,small volume,large torque density,high power factor and wide speed range.Since new energy vehicles use batteries as energy,it is of great significance to study control strategies and improve the utilization efficiency of electric energy.Due to various operating conditions,such as acceleration and overtaking,it is necessary to study the flux-weakening control strategy of the motor,so that it can run stably above the rated speed.This paper first introduces the principle of vector control of motor,SVPWM technology for research,research on its principle and implementation methods,expounds the difference of five and seven section SVPWM vector insertion mode.Secondly,the mathematical model of PMSM is introduced,and the difference between the SPMSM and the IPMSM is analyzed by figures and words.For the control strategy below base speed of PMSM,the traditional vector control strategy of4)_{（9）=0 cannot use the reluctance torque of the IPMSM,so the power utilization efficiency is low.The control strategy of maximum torque per ampere（MTPA）can make full use of the permanent magnet torque and reluctance torque of the motor.The optimal working point trajectory of the stator current under the control of MTPA is obtained by solving the algorithm.Then the loss of the motor is analyzed,and the composition of the loss is analyzed.Since the d-axis component and the q-axis component of the stator current of PMSM are coupled,the stability and effect of control will be reduced during operation.Therefore,the decoupling idea is introduced to study the decoupling strategy based on voltage feedforward,which improves the dynamic stability of the system.Through the construction of simulation module,the vector control strategy of4(}（9）=0 and the control strategy of MTPA based on voltage feedforward decoupling are compared and analyzed,and the effectiveness and superiority of the control strategy of MTPA is verified.Aiming at the problem that PMSM needs to run above base speed in some working conditions,this paper analyzes the principle of flux-weakening control,studies the algorithm formula of flux-weakening control based on equation,expounds three operating regions,analyzes the operation process of the motor and the working point track of stator current.Because the flux-weakening control based on equation uses two current regulators,the dynamic performance of the vehicle needs to be improved in the process of high-speed operation,and the load capacity is weak.Therefore,the single-current flux-weakening control based on CCR-VQV is studied,and the control trajectory of the stator current and the given method of q-axis voltage under this method are analyzed.Finally,the simulation results show that the dynamic performance of the method is better and the load capacity is stronger.Finally,the control system platform of PMSM is built,and the design of hardware control system and software flow are introduced.The experiments of MTPA control strategy and single-current flux-weakening control based on CCR-VQV are carried out to verify the effectiveness and feasibility of the two control strategies.In this paper,there are 69 figures,6 tables and 86 references.