| In recent years the rapid development of the automobile industry brings convenience to travel, but also brings lots of trouble. The traditional fuel vehicles rely on oil resource excessively, and causes air pollution by exhaust emissions which affects life seriously, so traditional cars need to be improved to new energy vehicles.Today electric vehicle is a hot development direction, but the energy storage technology is a key factor contain the development of electric vehicles. Single battery as the power source leads to insufficient power due to its low power density, long term influence on the battery is great. This dissertation studies the composite power supply system which joined super capacitor with high power density. By studying the structure and energy control strategy of the hybrid energy storage system improve the energy storage technology of the electric vehicle, in order to improve the development of the electric vehicle.This dissertation outlines the present situation of composite energy storage electric vehicle development at home and abroad. Then analyzed the working characteristic of the energy storage power, through charging and discharging experiments of the battery and super capacitor, designed the topological structure of composite energy storage system considering the characteristics of bi-directional DC/DC converter.Then analyzed the specific working conditions of DC/DC converter and the composite energy storage power in the operation of vehicle.According to the analysis of composite energy storage system working situation and the traditional logic threshold control strategy, designed the energy control strategy based on the composite energy storage system combining with the working characteristics of composite energy storage system, namely when the car is in acceleration, constant speed and braking mode, composite energy storage system has different working condition in order to meet the demand of the car. Then the electric vehicle was simulated based on the composite energy storage system with CRUISE,according to the simulation results preliminary verified the rationality of the composite energy storage system and its control strategy.According to the needs of the energy storage system designed the hardware and software. DSP TMS320F2812 of TI is adopted as main control chip of composite energy storage system. The design of hardware includes: super capacitor voltage detection circuit design, super capacitor monomer over-voltage protection circuit, car cruising, acceleration and braking mode detection circuit design, IGBT drive circuit design, power supply unit and CAN circuit design; the design of software includes function of GPIO configuration, AD conversion, CAN communication and PWM wave generation, etc.Finally, the composite storage systems and energy control hardware unit was built in accordance with the requirements of the design, this platform was debugged and experiment. The experimental results show that the composite energy storage system is rational, the energy control strategy is feasible, and the system runs stable. |
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