| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系 === 106 === Resonant converter with wide input voltage and low current ripple is proposed in this thesis, and applied to low input voltage and high voltage output systems such as fuel cells and renewable energy. The proposed circuit is a two-stage architecture. A conventional boost topology is employed in the first stage to increase the input voltage range and a current-fed resonant converter adopted in the second stage for galvanic isolation and dc/dc conversion. The second stage topology are combined with an interleaved boost and a full-bridge LLC resonant converter, to reduce the number of components counts, and make the advantages of the two gathered in the circuit. The pulse-frequency modulation (PFM) control is employed in the second stage, to reduce the input current ripple. The output side of the proposed converter is composed of voltage doubler rectifiers, for high voltage output application. Based on the characteristics of the LLC resonant converter, the zero voltage switching (ZVS) for whole power switches can be achieved under all load conditions, and the zero current switching (ZCS) of the output rectifier diodes at heavy load is reached. Therefore, the switching losses on power switches and the reverse recovery current losses on the output rectifier diodes are significantly reduced.
Finally, the design and the operation modes of the proposed converter will be analyzed in depth. A 800W prototype with an input voltage of 24V-76V and an output voltage of 400V has been built and tested to verify the operational principle analysis.
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