The Research Of Field Weakening Control Methodology For Induction Motor Used In Electric Vehicle

With the development of modern society, vehicle is more and morenormal in our daily life, meanwhile it indicates more oil consumption. Asit is estimated, the traffic oil consumption will take up62%of whole oilconsumption in2020. Electric vehicle, a clean energy vehicle solve thisconflict and is given more and more attention by plenty of countries.The research situation and developing direction is firstly introduced.Then compare different present control schemes. Conclude the motormodel as the basic of latter research based on the rotor flux-oriented usingthe coordinate transformation. Introduce the SVPWM and give the propersteps and calculation method in hardware.Divide the operation of AC motor into3control periods throughvoltage and current limitation in the coordinate. Analyze the operationsituation, especially torque and factors to restrict it in each district. Thenanalyze two conventional methods and come up with an improvedtorque-output field-weakening method. This algorithm uses the twoadjacent vector’s action time as the sign for the field-weakening and give the limitation of torque current through the analysis about the equation oftorque.The simulation model of the experimental induction motor is built inMATLAB/SIMULINK. The result shows that the speed response isquicker, the exciting current is more stable, output torque while highspeed is more realistic for the improved method than the voltage loopcontrol method. Then the simulation in the normal operating mode, highload mode and braking mode all verify the correctness and excellence ofthe algorithm which is reflected in the static stability and quick response,small overshoot while being influenced by outer atmosphere.The selection of induction motor and battery is given. Then choosethe ST company’s STM32F103x8as the CPU chip of the control circuitand Infineon’s FS400R06A1E3as the IGBT module of drive circuit andbuild the control and drive circuit. As for the software, the moduleprogramming thought is adopted and SVPWM calculation, current ADsampling module are programmed based on the main program.