| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 98 === In recent years, the environmental pollution causes global warming, acid rain, destruction of ozone layer, etc. Because the environmental pollution has become more and more serious, the emissions of exhaust must be controlled. The demands of generation for clean energy, such as solar cells, wind turbines and fuel cells, etc, are increasing. Since fuel cells are not affected by the climate and can continuously generate energy by keeping supplying fuel required, they are more appropriate than solar cells or wind turbines. However, fuel cells are not like the conventional secondary batteries, so they can not store energy. When the load increases, the output voltage will drop substantially. Nevertheless, they feature high power density, high output current capability, clean generation and high efficiency, etc. Because the output voltages of fuel cells are of low level and wide variation, a DC-DC converter must be introduced between fuel cells and loads to provide a stable output voltage for the loads.
In this thesis, a 2-kW step-up DC-DC converter, of which the configuration is a current-fed full-bridge topology, is studied and implemented. The current-fed step-up full-bridge converter and design procedures will be analyzed and proposed, respectively. Due to hard switchings, voltage spikes will be occurred across the switches at turn-offs. In order to prevent the switches from destruction, snubbers are adopted. Finally, a 2-kW current-fed step-up full-bridge converter is implemented and tested to verify the theoretical analysis.
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