Regenerative braking system for series hybrid electric city bus

Abstract

Regenerative braking is an efficient method to achieve better fuel economy and lower emission and to decrease the energy crisis and the environment pollution. The regenerative braking technique for one series hybrid electric bus is studied. The scheme of the regenerative braking system, RBS, is designed, the control strategy is given out and simulated, and the system is tested on the hardware-in-the-loop environment and the actual vehicle. In the new RBS, the friction braking force can be adjusted, based on the analysis and modification of the former braking system. The RBS is mainly made up of the adjustable friction braking system, the motor and battery, which arc components of the hybrid electric power train. The simulation model of the RBS is built. The control strategy is designed and analyzed. The affection of the initial vehicle speed, the SOC(State Of Charge) of battery, the limit of max charge current of battery, etc. to the energy regeneration efficiency is analyzed by simulation. The performance of the RBS is also analyzed based on the Chinese Urban Bus Driving Cycle. The hardware-in-the-loop test-bed of RBS is constructed. The test-bed consists of a braking subsystem built according to the braking system of the bus, the simulative motor & battery and other parts of the bus in dSPACE, and the measurement subsystem. The performance of the friction braking force adjusting, the ABS system, the regenerative braking, and the coordinative control of the regenerative braking system and ABS system, is tested on the hardware-in-the-loop test-bed and the actual vehicle. The results indicate that, the new RBS can recover more braking energy with good brake driveability, and can cooperate with ABS system to guarantee braking safety. Copyright © (2007) by the Electric Drive Transportation Association.