Abstract:

This paper deals with the emulated engine compression braking （EECB） of parallel hybrid electric system. When the vehicle is in a coasting mode, the electric clutch is disengaged, and the electric motor （EM） provides negative torque to emulate the engine drag torque for charging the battery, thus making full use of the coasting energy. Then, by taking into account the EM generation efficiency and the battery charging efficiency, an EM torque optimization （ETO） control algorithm is proposed to maximize the actual electric power recuperated by the battery and to obtain the optimal EM torque and the corresponding optimal shift-control rule of the automatic me- chanical transmission. Simulated results indicate that the EECB with ETO offers a greatly improved battery state of charge.

Key words: hybrid power system, emulated engine compression braking, electric-motor torque optimization, effi-ciency