| Summary: | 碩士 === 國立成功大學 === 電機工程學系碩博士班 === 101 === This thesis proposes a buck converter with coupled inductor and switched-capacitor techniques. By employing the proposed topology, the DC-DC converter achieves high voltage conversion ratio. The switched-capacitor cell is not only used to achieve high step-down voltage gain, but eliminate the voltage spike induced by the trapped energy in the leakage inductance of the coupled inductor. Besides, the auxiliary switch in switched-capacitor cell has zero-voltage-switching (ZVS) feature. Thus, the main switch of the converter can sustain a lower duty ratio and a lower voltage stress. Moreover, the inductor current flows in the opposite direction while it drops to zero, and the main switch can be turned on with zero-voltage-switching. Since both main and auxiliary switches have ZVS feature, switching loss can be reduced, and conversion efficiency can, therefore, be improved significantly. A prototype circuit of 200W, 200V input-voltage, and 24V output-voltage has been implemented to verify the proposed converter. The experimental results have shown that voltage spike can be greatly suppressed and the maximum efficiency can reach 95.8% and the overall efficiency is almost above 93%.
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