Study On Optimization Algorithm For Hybrid Electric Power System Used In Electric Vehicles Cruise Control

With the challenges of energy and environment crisis, electric vehicle(EV) hasbecame an important developing direction for the future new energy vehicles becauseof its advantages of high efficiency, low nosie and zero emission. But there are stillmany problems in the development of EV, mainly on the continues mileage in onecharge、battery life、motor and its control technology and some other issues. Based amicro EV, this dissertation focuses on the system configuration optimization andenergy management. Selected the hybrid electric power system(HEPS) andmaster-slavemotor drive system(MMDS) as the research object, than optimized andmatched the parameters of MMDS. After that, the hierarchical vehicle control strategyis designed, an energy optimization algorithm of electric vehicle cruise control systemand power distribution optimization algorithm of HEPS is proposed, in order toprotect the battery、reducing the system energy consumption and extending thedriving range.Firstly, the topology structure of HEPS and mechanical structure of MMDS aredetermined, based on analysis and comparison of different system configurations ofelectric vehicles. Then building mathematical model of those key components, i.e.lithiumionbattery, super capacitor, DC/DC converter and drive motor. Further,optimized and matched the parameters of MMDS. By using the MATLAB/Simulinkand ADAMS software, the feasibility of MMDS is verified through simulation.After that, an optimization algorithm of electric vehicle cruise control system isproposed based on direct multiple shooting algorithm(DMSA), in which the lookahead road grade information over spatial-domain is considered. The control modelsare converted from the time-domain to the spatial-domain, and a performanceobjective function for both energy economy and tracking safety is proposed. Thecontrol effects of the optimization algorithm have been verified by usingMATLAB/Simulink. The simulation results indicate that, for the electric vehicle isable to guarantee its tracking safety, and the operating efficiency of the electric motoris improved, which increases more than3.8%(comparing with the conventional cruisecontrol system) especially for those cases with large variation of the road grade.Finally, the hierarchical vehicle control strategy is designed, upper algorithm ismotor efficiency optimization algorithm of cruise system, and the lower algorithm ispower allocation optimization algorithm of synergic electric power system. Then thecontrol effects of power allocation optimization algorithm of HEPS have been verifiedby using MATLAB/Simulink. The simulation results indicate that, the super capacitorhad a prominent impact on smoothing performance of the battery within synergic electric power system. It is benefit to extend the battery cycling lifetime and improvesystem efficiency.