Research on Control Strategy for Regenerative Braking of a Plug-In Hybrid Electric City Public Bus

Regenerative braking is an efficient method to achieve better fuel economy and lower emission. The control strategy of regenerative braking for one plug-in hybrid electric city public bus with ABS system is studied. Under Qingdao urban working cycle, the scheme of the regenerative braking system has been developed, the control strategy is given out and simulated. The ideal braking force distribution on front wheel and rear wheel are analyzed. In the control strategy, power is supplied by regenerative braking when lower braking intensity is required and by proportionally combination of regenerative braking and frictional braking deduced by fuzzy-logic control strategy when higher braking intensity is required. And front wheel with rear wheel frictional braking and unchanged motor torque are combined by ideal braking force distribution when braking intensity up to motor´s max torque. And the logistic upper & lower limit value of ABS controller is correspondingly adjusted. The results indicate that, the new control strategy for regenerative braking of plug-in hybrid electric city public bus with ABS system can recover more braking energy with good brake drive ability, and can cooperate with ABS system to guarantee braking safety. And it improves the braking directional stability of the PHEV bus. It also conforms to ECE laws and regulations. Especially under the situation of urban working cycle of Qingdao, the energy consumption can be reduced by 15% ~20%.