Design And Prototyping Of Vehicle Control Unit For A Pure Electric Vehicle With Battery-Ultracapacitor Dual Energy Sources

With the increasing seriousness of environmental pollution and energy shortage, developing the Electric vehicle (EV) have been considered as one of the effective solutions to alleviate the two big problems. The power system of pure electric vehicle in this research adopting the "Battery+Ultra-capacitor" combined energy structure, gives full play to not only the high specific energy of battery but also fast charge and discharge characteristics and high specific power of ultra-capacitor to extend the battery’s life and improve the vehicle power performance through their coordination work. Vehicle control unit, as the core component of EV control system, will affect the vehicle performance and fuel economy directly. Therefore, it is significant for EV technology development to design VCU for electric vehicles with Battery-Ultracapacitor dual energy sources and give full play to the dual energy sources.In the paper, it analyses the power system structure of pure electric vehicles with dual energy sources and determines the parameters of the key components. According to vehicle driving requirements and dual energy sources characteristics, it makes two different vehicle control strategy and designs the vehicle control system model including the motor model, the dual energy source model and the control strategy model, which is based on the MATLAB/Simulink software. Then its control strategy is determined by comparing the simulation results of the different ones. The VCU design is according to the technical and function requirement, including the hardware design and software design. Considering the actual requirement in EV, in this paper, it defines the application layer protocol based on the SAE J1939. And the vehicle communication system is tested by the CANoe/MATLAB co-simulation. At last, the function of VCU is verified by HILS, which is based on the dSPACE platform.The simulation and experimental results indicate that the vehicle control strategy can achieve the target of vehicle control and give full play to the advantages of dual energy sources. According to the CANoe/MATLAB simulation, the data transmission in bus system can reach the requirement of transmission real-time and accuracy. And HILS shows that the VCU is accordance with the requirements of the set.