Converter Design And Control In Fuel Cell And Supercapacitor Hybrid Power Generation System

Under the background of global energy crisis and people's increasing concern for environmental protection, the power generation based on fuel cell using the hydrogen as an energy source is one of the clean, green, and efficient renewable energy generation in the future. Its high efficiency, high power density, low noise, environmental protection and configuration flexibility features, makes the fuel cells are widely used in aerospace, transportation, communications, defense and other occasions. Fuel cells are electrochemical reaction due to internal, fast-switching in the load will make the the output voltage and current require the seconds-class adjustment of the time to reach a new balance, and this sudden change of load conditions may cause local index exceeded to affect its life. Therefore, due to the output characteristics of a fuel cell, the appropriate choice of auxiliary energy storage device, and the design of power electronic device for fuel cell power generation system, to compensate for its lack of dynamic response, stability, and efficient energy is very important research topic.In this thesis using the supercapacitor as as the energy buffer unit in fuel cell generation system, and designing the DC-DC converter after the fuel cell stacks, bidirectional DC-DC converters and the corresponding control method, to lay a good technical foundation for the future formation of a complete fuel cell-super capacitor hybrid power generation systemFirstly, the characteristics tests of fuel cell and supercapacitor are operated, and the experimental results can be used as basis provided for the design of the fuel cell and supercapacitor hybrid generation system. Secondly, a suitable DC-DC converter after the fuel cell which is proposed by our team is designed. Compared to the traditional single-phase boost converter, the topology can greatly improve the switching environment of the main switch, and the diode reverse recovery problem is effectively alleviated by the leakage inductance. The detailed analysis of its working principles, parameter design and experiment validation are presented in this thesis. Thirdly, a bidirectional DC-DC converter is proposed used for energy storage unit in a fuel cell system. By using coupled inductor interleaved structure, all the switches can achieve ZVS performance over a wide load. Phase-shifted plus PWM control technology is employed to reduce the rms of leakage current and improve change efficiency. The operational principles are analyzed and the the corresponding formula and the circuit parameter design method are presented, DSP digital controller is used to achieve the power control. Finally, the lkW experimental prototype is built to vertify the theoretical analysis.