| Summary: | 碩士 === 國立雲林科技大學 === 電機工程系碩士班 === 100 === A bridgeless isolated SEPIC converter with active-clamp snubber is presented. This converter uses the bridgeless topology to reduce the rectifier diodes and improve the efficiency. The proposed converter is operated on the fixed frequency, and its input current consists of CCM and DCM parts simultaneously. During some parts of the line frequency, the converter is operated in the DCM so it can achieve the high power factor and confirm to the requirement of IEC 61000-3-2 class D. Although the converter is partly operated in the CCM will decrease the power factor, the efficiency can be improved. In addition, the active-clamp topology can achieve the characteristic of zero voltage turn-on for all switches when the converter is in the CCM operation. The main switches in the DCM operation can also achieve the function of zero current turn-on.
The proposed converter is verified to be functionally worked by the experimental and simulation results based on the 150W prototype circuit and it also conforms to the requirement of IEC 61000-3-2 class D. Finally, the improved efficiency for the proposed converter can be further verified once the input current consists of the part of the CCM operation.
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