Study On FOC Of AC Asynchronous Motor For Electric Vehicles Based On Model

This thesis focuses on the vector control system of AC asynchronous motor for Electric Vehicles.Firstly,the paper carries on comparation of several drive motor,contrast vector control and DTC control,and gives the advantages of MBD(model based design)relative to traditional development process.For providing a theoretical basis for simulation and controller,this paper gives a detailed introduction of Clark and Park transformation.Starting with conversion of rotor to stator,this paper strictly derived the mathematical model of AC asynchronous motor in all sorts of coordinate systems and finally basic equations of vector control are obtained.The principle,method and essence of the SVPWM modulation is systematically introduced.In the terms of maximizing torque of full speed range,this article systematically elaborates the field-weakening theory based on voltage and currentlimit conditions.In Matlab/Simulink interactive development platform,simulation model of the whole vector control system is established,and the vector transform,the rotor flux observer,SVPWM,field-weakening are verified by simulation.Furthermore,the paper gives system dynamic response curve of each parameter of no field-weakening and field-weakening,respectively.Meanwhile,the simulation results are analyzed and illustrated in detail.The simulation results reveal that in the speed range of constant torque,constant power and constant voltage,rotor flux,speed and current can realize fast following response,and the motor torque has excellent dynamic performance and small torque ripple.The paper adopts the method of MBD(Model-based Design)to develop asynchronous motor controller software.The code generation tool of Matlab software product family-Embedded Coder,is used to transform simulink model of top level control strategy into C code for TI,C28x series DSP.Then,the bottom hardware driver of TMS320F28335 is written manually.Finally,the bottom hardware driver and top level control strategy is integrated in Code Composer Studio.The paper gives power-supply circuit,phase current sampling circuit,signal processing circuit for the optical encoder,CAN communication circuit of motor controller(using the customd protocol),PWM level shift circuit and BTS6143 highside driver circuit.A joint test hardware platform of VCU and motor controller is built to debug the software and hardware of the controller,the testing result demonstrates that the inverter can achieve good sinusoidal output current waveform,motor speed can track quickly and precisely,and the system has excellent dynamic response characteristics.