Study On Key Technology Of The Powertrain System In Fuel Cell Bus

Fuel cell bus is driven by electric motor using fuel cell as main power source and ultracapacitor or battery as assistant power. What FCB differs from traditional bus is its power sources and powertrain are mainly composed of electric components. Concerning environment protection and energy conservation, fuel cell buses have long term potential for future main stream buses. The dissertation discussed and analyzed some of the key technology of powertrain system in fuel cell bus.The dissertation introduced the conformation of FCB, the characteristics and safety quality of hydrogen energy and the hydrogen utilization equipment on vehicle. It also discussed several power train frameworks of three models in fuel cell bus which combines fuel cell with ultracapacitor as the power sources, and analyzed the advantages and disadvantages of different models. The control strategy of the powertrain was designed. According as the dynamic performance requirements and the power demand of the designed drive cycles, the parameters matching philosophies of powertrain was put forward. The related parameters of fuel cell, motor, ultracapacitor and the gear ratio of driveline were designed on the basis of theory deduction and engineering analysis.According to different requirements for communication in the vehicle, vehicle control network was built up based on CAN bus and LIN bus technology. The communication protocol and messages content of the VCU were designed. Message acknowledgment mechanism based on the PRI of ID was put forward to meet the vehicle communication requirement. The development and testing system of vehicle CAN bus network was designed and analyzed. It could simulate the function of the vehicle network and perform experiments to test the baud rate of network and correctness and veracity of messages to validate the design. The simulation model could be modified and optimized through adjusting the parameters of CAN communication. It offers the gist for the installation and debug of the CAN network in fuel cell bus.The function of the vehicle control unit was discussed and the energy flow control strategy of the powertrain system was presented. The working mode and power assignment of the powertrain system under different duty cycle were analyzed. The energy flow among the fuel cell engine, the ultracapacitor and the electric motor was designed.The dissertation expounds the philosophy of the V mode for developing the control system of the FCB powertrain system. Rapid Control Prototype technology and Hardware-in-Loop Simulation technology are also discussed. The test bench and control method of the hardware-in-loop-simulation experiments for the power train of the FCB was designed. It makes foundation for the R&D of the VCU.Simulation of the power train system was carried out in ADVISOR. The results show that the dynamic performance and the fuel economy fulfill the designed requirements for the FCB and the efficiency of the power train is satisfied. The parameter matching method is demonstrated to be feasible and valid. The experiments on the fuel cell and the electric motor were performed. The property of the current, voltage and power of the fuel cell meet the vehicle power requirement. The speed-torque property and power- efficiency property of the electric motor fulfill the dynamic requirement of the FCB.The vehicle performance experiments on the FCB were carried out. The results show that the maximum speed and acceleration time achieve or exceed the required index. On basis of the analysis of working principle in fuel cell, the theoretical method and experimental method of the fuel economy in fuel cell bus was discussed. It is useful for the analysis and estimation of the mileage of FCB and help to improve fuel economy.