| Summary: | 碩士 === 國立成功大學 === 電機工程學系碩博士班 === 101 === Three-port converters are popular for stand-alone renewable system applications because of less components and smaller volume. Conventionally, non-isolated three-port converters are not suitable for high conversion ratio applications, because the voltage gain is limited by the parasitic elements of circuit. Isolated three-port converters can achieve high conversion ratio by adjusting the turns ratio of the transformer, but the component count is high and the leakage inductance of the transformer will reduce the efficiency of the circuit. In this thesis, a novel three-port converter with high conversion ratio is proposed. The converter combines techniques of high step-up converters with a non-isolated three-port converter; therefore, a higher conversion ratio can be achieved with a lower turns ratio and a reasonable duty ratio. Also, the converter can achieve a high conversion ratio and high efficiency simultaneously. Operating principles, steady-state analysis, and boundary analysis of the converter are presented and discussed. Finally, a prototype of the proposed converter with a low input voltage port for PV source, a bidirectional port for storage elements, and a high voltage port for output is implemented to verify the theoretical analysis. The power flow control of the converter is also built and tested with a digital signal processor (DSP).
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