Abstract：LLC resonant converter is a kind of practical soft-switching DC-DC converter, which can realize soft switch in the range of full load. In the occasion of low-voltage input and high-voltage output, this paper studies the secondary side leakage inductor has effect on the actual gain curve of LLC resonant converter. The methods of improving the external characteristics and efficiency are proposed. Faced with the need of high step-down converters, the structure of PSSP sharing the switching network is proposed to reduce the resonant leakage inductance in order to improve the external characteristics. This paper presents the analysis of high step-down LLC transformer and the design using. Besides, this paper analyzes how the differences of transformer parameters affect the current unbalance of PSSP. The methods of designing and debugging LLC resonant DC-DC transformer are given. An experimental prototype converter of 250W has been built.
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2015, Vol. 30 
