| Summary: | 碩士 === 龍華科技大學 === 電子系碩士班 === 93 === In recent year, the switching device of the switching power converter usually uses metal-oxide-semiconductor field-effect transistor (MOSFET) and insulated gate bipolar transistor (IGBT). However, these devices always result in some commutation losses when they are switched. For the individual characteristics of both semiconductor devices, this thesis proposes two soft-switching topologies which are zero-current-switching (ZCS) flyback converter and zero-voltage-switching (ZVS) flyback converter to improve this problem. The operating principle and circuit analysis for these soft-switching topologies will be explained in detail in this thesis. Conventional hard-switched flyback converters suffer from the problems of switching loss and severe voltage stress on the switching devices due to the inherent flyback transformer leakage inductance. In the proposed soft-switching flyback converter, the leakage inductor has been included in the soft-switching auxiliary circuit. Thus, the previous problem can be avoided in the thesis. The principle of operation, theoretical analysis, and experimental results of the soft-switching flyabck converter, rated 100W and operating at 80 kHz, are provided in this thesis to verify the theoretical predictions.
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