Study On Energy Control For Driving System Of Electric Vehicle

Electric vehicle, for its low pollution to the environment, low working noise and being independent of traditional energy, has led the development of New Energy Vehicle. The main purpose of this dissertation is to deal with the energy control problem which EV experiences as working under complicated conditions. On the basis of the driving system of EV, the mathematical modeling, the charging modes of batteries and different conditions of EV are analyzed.A bi-directional DC/DC converter is used to deal with the complicated relationships between the voltage change of battery, the performance of the driving system and the recycle of regenerative braking energy. Based on the characteristics of the driving system, the topology of the bi-directional DC/DC converter is chosen and the control strategy is made to keep voltage stable in driving conditions and current stable in regenerative braking.State-Space Average Modeling is employed to model the bi-directional DC/DC converter. The working process and model characteristics are analyzed while the converter is working at different states. In addition, the battery voltage change and load current change which would cause the change of converter model are also studied by using MATLAB software.Models of Boost converter with negative voltage feedback and Buck converter with negative current feedback are established. Nonlinear PID control strategy is used to improve the performance and anti-noise ability of the energy control systems which are with traditional PID regulator.Modeling and anti-noise ability analysis of bi-directional DC/DC converter are carried out by MATLAB/SIMULINK. The performance of driving system with and without energy control converter are compared which leads to the conclusion that bi-directional DC/DC converter has effectively controlled the DC line input voltage and regenerative braking output current. Further more, energy control system employing Nonlinear PID control strategy is proved to have a better performance and anti-noise ability by comparing with the system with traditional PID regulator.