Research On Drive And Regenerative Braking Control Strategy For Plug-in Four-wheel Drive Hybrid Vehicle

With the increasing shortage of energy and the tightening of emission regulations,the traditional automobile industry is in urgent need of transformation to the new energy automobile industry.Because plug-in four-wheel drive hybrid vehicles combine the advantages of pure electric vehicles and traditional vehicles,they can reduce emissions and save energy,and have great development prospects in the future.The hybrid system is more complicated while the drive and regenerative braking control strategy is the most important part of the vehicle control strategy.It is necessary to research and solve the problems of energy recovery and utilization,which can have the certain theoretical significance and application value to improve the power and economy of the vehicles.In the process of studying the vehicle control strategy of the hybrid vehicle,the related research on the drive and regenerative braking is carried out.Firstly,the system structure of the hybrid system is analyzed.The powertrain parameters are matched according to the dynamic target and the cyclic working condition.Based on the logic rule control theory,the battery state of charge and the demand torque ar e used as the control variables and determine the defining conditions for driving mode switching.In series mode,the engine is operated at a constant economic operating point,and in parallel mode,the low battery level and high demand torque are separately controlled,and the signals of clutche,CVT,generator and so on are controlled in each working mode.The working principle,advantages and disadvantages of the pedal decoupling and undecoupled braking system are compared and analyzed.The braking analysis of the cycle working condition and the emergency braking test of the actual vehicl e are provided to theoretical guidance for the research of the regenerative braking strategy.Considering the safety of power battery charging and discharging,a regenerative braking strategy suitable for pedal decoupling system is studied.The optimized regenerative braking control strategy based on dual motor arrangement are proposed,which can improve the braking stability and energy recovery rate.The vehicle control strategy model was built in Matlab/Simulink and the vehicle model built in AVL-Cruise was joint simulated.The results of simulation verified the effect of power matching and the influence of control strategy on vehicle energy consumption.After a series of co-simulation experiments,the vehicle control strategy of the plug-in four-wheel drive hybrid vehicle studied in this paper can meet the dynamic design goals.Compared with the unoptimized regenerative braking control strategy,the improved control strategy has nearly doubled the contribution of the NEDC pure electric mode driving range.Under the WLTC cycle working condition,the energy recovery rate can reach 55.2%,an increase of 17.3%.In addition,the saving rate of fuel in the comprehensive fuel consumption assessment of 100 kilometers is about 19.7%,an increase of 6.5%.Therefore,the improved vehicle control strategy has obvious advantages and can reduce the energy consumption and emissions of the vehicles.