Development Of Hybrid System For Hybrid Electric City Bus

Electric vehicle (EV) is facing a development apex under the pressure of resource and environmental crisis. More and more EV products have been put into market with the development of electric technologies. Pure EV is difficult to meet sufficient distance, so hybrid electric vehicle (HEV) has been paid more attention recently.Vast operating data of the city bus have been acquired with the aid of data-acquisition system of the EV developed by writer. The data show the fact that the working conditions of the city bus exist lower speed driving, frequent acceleration and long-range engine idle operation which lead to bad fuel economy and emission. The series hybrid electric bus (SHEB) is referred according to the characters both of the city bus and HEV, and the concept of characteristic bus is concerned which can be described as "one route one bus".Based on the hybrid system, this thesis analyzes its components with detail. The advantages and disadvantages of the hybrid system have been researched compared to the classic vehicle, and the conclusion of efficiency optimization has been acquired.It's the key to realize the optimal efficiency of the hybrid system that set up an effective control strategy. Compared with the other control model, this thesis proposes a novel strategy that the power of the APU is adaptively regulated based on the power balance of the driving cycle. This strategy effectively solves the power distribution between the APU and batteries during the drive of the HEB. The power control model and multi-torque switching strategy of the driving motors control the charging-recharging current of the batteries within a wide range, which contribute to the improvement of the efficiency. The foundation of type selection and optimal matching for the hybrid system is established.APU system, AC induction motors driving system, multi-torque output system, regenerative braking system and battery management system make of the hybrid system. All the subsystems are integrated systematically by themulti-energy resource management system.Operating-data-acquisition system for EV developed by writer has the characters as follow: high sampling frequency, vast storage, anti-jamming, general-purpose interface bus, data transmission ability and etc. The system can well adapt to the EV operating data acquisition, which provides true and correct data for the valuation of the EV performance and following research work.