Control method of engine auxiliary braking for hybrid electric vehicles

A control method of the engine auxiliary braking of parallel hybrid electric vehicles for driving safety and ride comfort is proposed in this paper. Firstly, through an analysis on vehicle driving characteristics on downhill section, the proper timing of bring in engine auxiliary braking is chosen, and the dynamic coordination processes of starting motor and clutch during the bring-in process of engine auxiliary braking are analyzed. Then in order to keep vehicle speed stable during the process, a coordinated control strategy for driving motor in the process is put forward. Finally the strategy is verified by real vehicle tests. The results show that the proposed method can not only enhance the driving safety of vehicle in downhill section and the service life of drive-train components, but also evidently improve the ride comfort of occupants. ©, 2014, SAE-China. All right reserved.