| Summary: | 碩士 === 國立高雄第一科技大學 === 電子工程研究所 === 100 === Compared with conventional hard-switching mode, the soft switching technique causes smaller losses in applications of Switching Power Supply (SPS). The asymmetrical half-bridge converter with synchronous rectification and soft-switching technique uses turn-on and turn-off hours to achieve soft switching mode for reducing losses at high frequency, voltage and current stresses between two power switches. To reduce losses, multiplication of forward voltage and current, and increase efficiency of asymmetrical half-bridge converter, the super fast diodes are replaced with the synchronous rectification technique in secondary side of transformer. In this experiment, the turns ratio of transformer is designed to match duty cycles for devices with asymmetrical and complementary operation. Moreover, operating principle of circuit, analysis of steady-state and transient state, and design consideration are all discussed in this thesis.Finally, A 300 W prototype with 400Vdc input and 24Vdc output operating with PWM IC-L6591 is built and tested, and the efficiency at full load is 92.09% which verifies the feasibility of theoretical analysis.
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