Design Of Switched Reluctance Motor Control System For Four-wheel-independent-driven Electric Vehicle

With increased environmental pollution and energy crisis, etc., the electric vehiclewill be the inevitable direction of the future automotive industry, and four-wheel-independent-drive electric vehicle is regarded as the electric final drive form, as it hascompact structural arrangement, high transfer efficiency, fast response and so on. Motordrive system is one of the core components of electric vehicle, which directly affect thedynamic performance, ride comfort and handling stability of the car. Switchedreluctance motor is one kind of electric vehicle drive motor with great potential fordevelopment, because it has simple and reliable structure, low cost, small startingcurrent, big starting torque, wide speed range and high system efficiency. But, However,the switched reluctance motor has the problem of larger torque ripple, and the torqueripple directly act on the wheel, which deteriorate the vehicle’s ride and handlingstability. Therefore, the research and development of high-performance switchedreluctance motor control system has important academic significance and practicalvalue. In this paper, the control methods is studied to solve the problem of high torqueripple in switched reluctance motor from the view of motor control, and the hardwarecircuit of motor control system is designed. The main contents of the dissertationinclude the following:①The design parameters of switched reluctance motor are calculated accordingto the parameters and the designed dynamic performance of electric vehicle. Theworking principle of SRM is introduced, and the basic equations and nonlinear model isestablished.②Three basic control methods of SRM is analyzed, and for the angular positioncontrol, the impact of turn-on angle and turn-off angle on motor performance isanalyzed. The simulation model of the angular position control of the SRM isestablished on the basis of switching angle optimization, and simulation results showthat the angular position control performs well under variable operating conditions.③For the defects of the conventional control method, the direct torquedistribution control to improve the torque ripple is studied. The simulation model ofdirect torque distribution control system is built based on Matlab/Simulink. Theterminal sliding mode controller is designed. And the comparisons and evaluationsamong terminal sliding mode control, PID control and angular position control are carried out. The simulation results show that the terminal sliding mode control not onlyreduces motor torque ripple, but also improves the robustness of the system.④The hardware circuit of the control system is designed based on Freescalemicrocontroller MC9S12XF512, which includes the minimum system circuit, the phasecurrent detecting circuit, the phase voltage detecting circuit, the rotor position detectingcircuit and the driving circuit. The test results show that the hard ware circuit isreasonable and the entire control system hardware can work properly.