Digital Realization Of A Bidirectional DC/DC Converter In Electric Vehicle

The exhaustion of petroleum resources and the pollution of the environment are the common concerned important problems at home and abroad in recent years. Electric vehicle can largely reduce the dependence on oil resources. It becomes the main way of realizing the sustainable development of the world automobile industry. Because fuel cell has the advantages of the low pollutant emission and high efficiency, it has attracted worldwide attention. The fuel cell electric vehicle becomes an important development direction of new energy car. However, the dynamic response of fuel cell electric vehicle is always slow. The fuel cell electric vehicle can not be quick to recover energy and cannot be quick to provide greater traction power, which restricts the development of the fuel cell electric vehicle. The auxiliary storage system of electric vehicle can greatly improve its shortcomings. The auxiliary storage system is mainly composed of super capacitor, bidirectional DC/DC converter and its control circuit. It recovers the feedback energy through the bidirectional DC/DC converter and provides the required additional energy through the super capacitor. Bidirectional DC/DC converter is the key to energy bidirectional flow. The thesis introduces a interleaved dual phase half-bridge bidirectional DC/DC converter as an energy management unit, which is suitable for auxiliary storage system of electric vehicle.First, the thesis analyses all kinds of isolation and non-isolation bidirectional DC/DC converter and selects the smaller voltage and current stress for bidirectional DC/DC converter. In order to further reduce current of the individual power switching device and in order to improve the working efficiency of the converter, two half-bridge bidirectional DC/DC converter are paralleled and interleaved dual phase half-bridge bidirectional DC/DC converter are composed.Then, according to the design requirements of auxiliary storage system, the main circuit parameters and control strategy of interleaved dual phase half-bridge bidirectional DC/DC converter are designed. In the Matlab/Simulink environment, the simulation control system is tested about the thesis. The simulation tests lay a foundation for suitable main circuit parameters, good control strategy and appropriate PI parameters.Finally, the master circuit and control system hardware test platform are set up with power of300W for interleaved dual phase half-bridge bidirectional DC/DC converter, including main circuit, Metal-Oxide-Semiconductor Field-Effect Transisitor (MOSFET) drive circuit, MOSFET protection circuit, voltage sampling circuit and conditioning circuit, current sampling circuit and conditioning circuit, auxiliary power supply circuit, etc. The DSP TMS320F2812is used as the core of the digital control system. Each subroutine of system is narrated in detail and the control system is debugged with C language in Code Composer Studio (CCS) compiler environment. Test show that the design of the interleaved dual phase half-bridge bidirectional DC/DC converter comply with the design requirements, and digital control has a good performance about the super capacitor charging and discharging test.