A Control Strategy Study On Regenerative Braking System Of 4WD Hybrid Electric Vehicle

Hybrid Electric Vehicle (HEV) is a new style vehicle, which is combined coventional vehicle with electric vehicle. It is not only keeping low mission of Electric Vehicle, but also inheriting the excellent performance of conventional vehicle. So it can improve mission and fuel economy of conventional vehicle obviously, increase running distance of HEV, become the develping emphases of cleansing vehicle in the world now.Regenerative braking is one of the prominent excellent for HEV.When HEV is braking, regenerative braking system will make the motor become a generator for making kinetic energy to electric energy and supplying the whole braking forces or partial braking forces at the same time. Finally, electric energy is saved into the battery pack. Regenerative braking not only realizes the braking and deceleration, but also reduces the oil consuming and mission. So regenerative braking has a direct impact on fuel economy, emission and vehicle security, which is also one of key techniques for HEV.Regenerative braking energy effect lies on the driving format of vehicle. For 4WD HEV, the recycle effect is the best, front drive vehicle can but recycle portion energy. Focus on 4WD Hybrid Electric Vehicle. The deeply theoretical researching, system simulation and evaluate are completed in this paper. The main results include:1. Based on mild hybrid electric vehicle with ISG, the scheme on power-train of 4WD HEV is designed, and according on its characteristic, the working mode is establishing corresponding.2. According on the vehicle parameter and the power goal, the types of dynamical transmission parts (engine,front and rear motor,battery,trasmission) are selected, and their parameters are designed.3. The braking force distribution strategy on conventional vehicle is analyzed. The braking intension curve on front and rear motor is gotten according analyzing motor. A regenerative braking force distribution strategy of 4WD HEV is assure, which not only can keep the braking security, but also keep high efficient energy recovery.4. Basing on motor and battery experimentation, the changing rules of motor generating and battery charging efficiency are analyzed, a generating optimal working Line with high efficiency combined battery with motor is assured, and manual transmission (MT) shift strategy is proposed which makes motor work in the optimal line during braking.5. The driver model is built,the working mode of vehicle is built also.Based on forward modeling idea, according to bench experiment data of the engine,motor and battery, combined with numeric modeling and theory modeling, forward simulation model for regenerative braking system of 4WD hybrid electric vehicle is built.6. The evaluation indexes for regenerative braking system are proposed. The regenerative braking system models are simulated and analyzed under the typical braking modes on diffirent state of charge (soc) and speed, and are simulated and analyzed under the city cycles. The simulation results show that the regenerative braking control strategy not only can satisfy vehicle security but also keep high efficient energy recovery.