Research On Direct Torque Control Of Permanent Magnet Synchronous Motor For Electric Vehicle

As a representative of the new energy vehicles, Electric vehicles eased the pressure of energy shortage and environmental pollution of the automotive industry facing with its advantages of less polluting, lower noise, easy maintenance and simple structure. The development of electric vehicles will be brought into a higher stage by permanent magnet synchronous motor (PMSM) for the characteristics of a small size, light weight, high control performance. Therefore, researching on PMSM drive control algorithm is valuable for electric vehicles engineering.Firstly, by establishing the PMSM mathematical model in a two-phase rotating coordinate system, PMSM model is built using s-function module in MATLAB/SIMULINK environment which is used for dSPACE hardware in loop (HIL) simulation platform. The dynamic characteristics of electric vehicle performance are analyzed, and the traction characteristic curve of PMSM witch meets requirements of electric vehicle drive is given in the paper.Secondly, the direct torque control (DTC) theory of PMSM is analyzed, and a PMSM stator flux estimation method is proposed by comparison for the stator flux calculation of PMSM and asynchronous induction motor, In addition, the maximum torque angle of the motor and the stator flux reference value limits are calculated. Based on the operating characteristics of frequent acceleration and deceleration of electric vehicle, the operation of low velocity zone and high-speed zone is simulated. To realize the design and research of constant torque control and constant power control algorithm, two models based on switching table structures and space vector PWM algorithm for DTC is set up using the MATLAB/SIMULINK tool. The detail of the implementation method of each module is introduced respectively. The results of the simulation for the electric vehicles dynamic characteristics show that the system has a good steady-state performance and fast response.Finally, the main circuit model is built in the dSPACE hardware in loop simulation platform, and the ControlDesk PC monitor interface is designed. By programming the DTC algorithm of PMSM based on TMS320F2812DSP, the constant torque start-loop simulation experiment on DTC of PMSM for electric vehicles is completed. Simulation results show that the speed of the motor can follow the changes of motor torque well, and the system has good dynamic response and small ripple in steady-state operation.