Research On Energy Management Strategy Of Hybrid Off-road Vehicle With In-wheel Motors

Off-road vehicle has large full load weight and complex driving cycle,which requires high power/torque output capacity of power system.Hybrid vehicle has excellent dynamic performance,outstanding energy-saving effect,high safety and stability and so on because of multi-power sources and complementary output characteristic.Therefore,the application of hybrid technology in off-road vehicles can greatly improve the overall performance.In this thesis,an off-road vehicle is taken as research object.For power system dynamic response and fuel economy optimization problems of in-wheel motors drive hybrid vehicle,off-road driving cycle,power system match and energy management strategy and so on key problems are studied.Aim at off-road vehicle complex driving road conditions and changeable terrain,the off-road driving cycle is constructed by means of vehicle autonomous driving and complete driving cycle characteristic parameters' deviation degree and similarity degree analysis in off-road test road of DingYuan Automotive Proving Ground.The series hybrid system structure with inwheel motors is identified by analyzing hybrid vehicle configuration and off-road vehicle characteristics.In-wheel motors,engine,generator and battery are selected and matched by analyzing the requirement of typical conditions and off-road driving cycle.Based on hybrid vehicles power system characteristics and working mode analysis,the energy management strategy design principles are proposed.For the strategy key parameter—demand power,real-time power acquisition algorithm and an adaptive markov chain power prediction algorithm are designed.Considering off-road vehicle demand power time-variability,a variable area equivalent fuel consumption minimization strategy is designed to optimize vehicle fuel economy.Using the predicted demand power and driving power response feedback adjustment to improve power system response characteristics.A complex energy management strategy based on VAECMS optimization is established,which includes power control and energy management control.Hybrid vehicle model and energy management strategy model are established respectively in AVL/Cruise and Matlab/Simulink,and the correctness of vehicle model and off-road driving cycle are verified.Joint simulations under typical conditions and off-road driving cycle are carried out.The simulation results show that,compared with the composite rule energy management strategy,the strategy designed in this thesis can improve power system dynamic response characteristic,optimize vehicle fuel economy and maintain battery SOC stability.The complex energy management strategy proposed in this thesis combines optimal strategy with regular strategy,which has power response control and energy management control functions.The strategy can improve power system response characteristic and vehicle fuel economy,which has theoretical guidance and engineering application value.