Simulation And Control Strategies Of Electric Vehicle With Composite Power System

On the background of energy saving, developing electric vehicles industry is an important way to deal with environmental pollution and depletion of resources. Because of its characteristics of energy saving, environmentally friendly and efficient, many countries increase the investment of electric vehicles industry. Due to the current technical barriers of battery power, the insufficient mileage still restricts the development of electric vehicles. As an emerging power, the ultracapacitor has an advantage of high specific power, fast charging and discharging, and long lasting. So the combination of it and battery has obviously advantages, which is an effective way to extend the driving range of electric vehicles.The performance of various power storage devices are analyzed in this article, and the advantages and disadvantages of them are compared. From the technical requirements of vehicle power supply, choosing battery and ultracapacitor to finalize the composite power; then the operating characteristics of batterry, ultracapacitor and bi-directional DC/DC converter are analyzed. On the basis of it the structure of composite power system is determined. While the simulation models of composite power and its components are built in Matlab/Simulink; focus on the control strategies of composite power, which are studied based on the works of pure electric vehicles, then designed three different power allocation strategies: logic threshold, fuzzy control and fuzzy neural network; and designed two structures of fuzzy controller. On the basis of completing ADVISOR secondary development, the two structures of fuzzy controller and three control strategies are simulated and comparative analyzed. Verifying the program of composite power and the control strategies are effective and adaptable.Simulation results show that: by the ultracapacitor "load shifting", discharging current of the battery in the composite power is significantly reduced, the change of its soc slows down, and the driving range of electric vehicle is increased, verifying the scheme of composite power is feasibility and superiority. In the three control strategies, the power allocation strategy based on fuzzy neural network can achieve power distribution better, ultracapacitors can play a better proactive regulatory role in the system.