Research On Controller Of Switched Reluctance Motor For Electric Vehicle

Firstly, the thesis presented the development and current situation of electric vehicle(EV). According to the requirement of electric vehicle drive motor, switched reluctance motor(SRM) was chosen for the electric vehicle drive system and relevant controller was also designed. Secondly, the basic major parts and mathematical equations were introduced for switched reluctance drive. And the equations were mainly about the phase voltage, flux linkage and torque of SRM. The system employed phase shifted current hysteresis control way as the control method, and embraced speed closed-loop regulation or average torque closed-loop regulation as the control strategy. In additional, the basic fundamental was introduced for the fuzzy regulator and fuzzy-PI regulator. Thirdly, the hardware circuit was briefly introduced for electric vehicle controller. A microcontroller,PIC16F1933, was adopted as the core control chip and some peripheral circuit designed correspondingly, which would include processing circuit of rotor position signal and A/D sampling signal, minimum microcontroller system and logic output circuit of control signal. Also, the MOSFET drive circuit was established with a bootstrap operating mode,which could provide two charging ways for bootstrap capacitor. The first charging way would loop through main power circuit and MOSFET drive circuit, and the other one could form charging circuit only by the unique bootstrap capacitor’s charging circuit. And the operating conditions were analyzed for four different switch forms to demonstrate the MOSFET driver’s application range. To squeezing the hardware cost, a parallel structure of power switches and diodes was applied into building the asymmetric half-bridge power converter. A capacitor snubber circuit was recommended to suppress the phase voltage spike and protect the power MOSFET switches. Besides, a flux detecting circuit was put forward to measure the flux linkage and internal resistance of winding coils, which would consist of a cascade connection of subtractor circuit and passive RC integrator. Then, the software design was suggested for electric vehicle controller. The paper has employed MPLAB development tool to design the main program and interrupt subroutine. The interrupt subroutine mainly contained phase shifted current hysteresis control procedure,average torque closed-loop control subroutine with fuzzy algorithm, rotor speed closed-loop control subroutine with fuzzy-PI algorithm and function subroutine of the controller. Lastly, the experimental platform was built up to test the electric vehicle controller. The operation property of MOSFET drive circuit was inspected under verifying working circumstances. The function test experiment was also conducted to testthe working performance of motor start-stop, speed acceleration, speed deceleration and braking response. Additionally, the paper performed some experiments to verify the average torque closed-loop control strategy.