A Study On Regenerative Braking System In A Series-parallel Hybrid Electric Bus

The regenerative braking is a key technique for electric vehicles to save energy and reduce emissions. During the regenerative braking, the vehicle’s braking energy is converted to the electricity and stored in the energy storage system for later use in acceleration or startup, meanwhile, the braking torque is produced to make the vehicle slow down. The regenerative braking system need to coordinate both the electric braking system and the mechanical braking system to ensure the braking safety and stability, and recycle braking energy as much as possible to improve the energy utilization efficiency of the vehicle. This thesis chooses a rear-wheel drive series-parallel hybrid electric bus as the study object. A novel regenerative braking control strategy is proposed for the hybrid electric bus through the theoretical analysis and the simulation model of the regenerative braking system is set up and analyzed in the ADVISOR software.Firstly, by the method of theoretical research, the braking dynamics Analysis of the hybrid electric bus is made and the critical components of the regenerative braking system are studied and analyzed. By means of the traditional vehicle’s braking force distribution method, a novel regenerative braking control strategy is developed based on the braking intensity on the premise of meeting the ECE braking regulations.Secondly, since the software ADVISOR has some limitations, the rear-wheel drive vehicle simulation model is got by a secondary development of the ADVISOR. According to the regenerative braking control strategy proposed in this thesis, the simulation model of the regenerative braking system of the hybrid electric bus is set up in the ADVISOR software.Lastly, the typical city driving cycle of China is selected as the test cycle of the simulation for the regenerative braking system, and the dynamic performances and the fuel economy of the hybrid electric bus are got. Besides, the effect of the braking energy recovery in the city driving cycle and different braking intensity driving cycles are also analyzed. The simulation results indicate that the braking energy recovery efficiency of the regenerative braking system is quite well and the proposed regenerative braking control strategy is feasible and effective. What’s more, the influences of some components’ parameters on the braking energy recovery are studied, which has some reference value to the research and development of the regenerative braking system.