Design And Optimization On Switched Reluctance Motor Drive System Used In Electric Vehicle

With the rapid development of automobile industry, the resources shortage and environment pollution becomes increasingly serious. Research and development on electric vehicles has become the major developing trend of automotive industry, which can protect environment and save energy. SRM has no permanent magnetic materials on its internal structure, and has the advantages of simple structure, easy maintenance, small starting current, frequently starting and large starting torque. Therefore, SRM has been attracted more and more attention in the field of electric vehicle.First of all, the operation principle and linear model of SRM drive system used in electric vehicle are introduced in this paper. And the finite element analysis software FEMM and simulation software MATLAB/simulink are used to build the nonlinear model of a 12/8 pole SRM with the rated voltage 60V and the rated power 4kW. Co-simulation of the electromagnetic analysis and the dynamic control of the motor are performed, comparing the simulation results of different torque share functions (TSF). From the simulation results, it can be seen that the coefficient of low-speed torque ripple can be decreased to about 12% by using the optimized TSF, which proves that the control strategy is very helpful to improve the low-speed torque ripple for SRM used in electric vehicle.Secondly, the control strategy of SRM drive system used in electric vehicle is introduced in the paper:the double closed loop control method based on acceleration feedback is adopted to ensure that the electric vehicle can be started quickly in all kinds of road conditions; the adaptive turn on angle control approach and current chopping control are both adopted to make the drive system has advantages of energy saving; in order to reduce the torque ripple of SRM, the traditional cosine TSF is optimized in the turn on angle and the function of turn off phase; to ensure that the electric vehicle can be slowed down and stopped safely and quickly, the EABS braking system is adopted which can achieve the electric and mechanical combined braking.Finally, based on the control strategies and the simulation results above, the experiment platform including power converter circuit, position detection circuit, protection circuit was build, which has a test prototype as control object, and DSPIC33FJ128MC706 as master chip. Meanwhile, the software system including the main program, interrupt program, speed calculation program and the implementation program of control strategies was designed based on the modularization method The expected results have been achieved such as smooth quick start, operation with load, the inhibition of low speed torque ripple and so on, on the experiment platform. The entire drive system are debugged and tested on the scene, the entire drive system are debugged and tested on a vehicle, and the experiment results show that the proposed control strategy is feasible in engineering practice which can make the electric vehicle is of faster starting performance, higher efficiency, more than 11% once charging mileage.