Research On Optimal Braking Energy Recovery Strategy For Switched Reluctance Motor In Electric Vehicle

As urban smog phenomenon occurring frequently, the government of our country has begun to adopt appropriate policies to reduce automobile exhaust as main pollutants, and promote the development of new energy vehicles. Although electric vehicles(EV) does not produce pollution on driving process, but capacity of on-board batteries as an energy source in EV has been limited and the technology of batteries has been into the bottleneck, that will cause EV insufficient battery life. Study on regenerative braking energy recovery systems in EV will alleviate the above problems. The efficiency of the driving motor as energy conversion devices will impact on the performance of regenerative braking energy recovery directly, the optimization research of driving motor working on braking process has very important significance.Firstly, several driving motor for electric vehicles(EV) or hybrid electric vehicles(HEV) is introduced briefly in this thesis, and advantages and disadvantages of driving motor are analyzed respectively and compared, SRM was selected as a driving motor for EV in this thesis. Secondly, domestic and abroad studying status and application prospects of SRM for all kinds of fields are introduced. Through comparison of structural characteristics of SRM, 12/8 pole is selected. And then its working principle of regenerative braking process is elaborated when SRM works at braking process, the linear model of SRM is qualitative analyzed, and mathematical relationship of current with inductors and rotor position angle is derived. Finally, SRM non-linear models is created by Ansoft, main sizes is optimized by Ansoft/RMxprt, meanwhile, study on effects of main structural sizes on output power. Creating dynamic model of SRM by Maxwell, and the angle is optimized in controller. Braking process based on precise nonlinear of SRM model is studied in detail to ensure the accuracy the data and correctness of analysis results in this thesis, which is significantly different from the traditional method.By post processing function of Ansoft, optimizing turn-on and turn-off angle by grid method to realize maximize braking energy recovery when 50 kW SRM working at braking process. By simulation analysis and data calculation, turn-on/turn-off/power and efficiency curve will be obtained. And combination of turn on angle and turn off angle corresponding speed will be list. Conclusion verification, the simulation results show that the method of optimization is selected in this thesis has more advantages and effectiveness compare with traditional principle based on minimization of torque ripple, and more regenerative braking energy will be recovery with this optimization method.