Analysis on the influence of the secondary parasitic capacitance to ZVS transient in LLC resonant converter

This paper analyzes the (zero voltage switching) ZVS process mechanism considering the parasitic capacitance of the secondary rectifier in an LLC resonant converter and presents the design considerations to guarantee the fully realization of the soft switching. When an LLC resonant converter is used as an unregulated converter (DCX) in telecom applications, the secondary parasitic capacitance has a significant influence on the ZVS process, and the dead time calculation is different from the conventional method. This influence, which is rarely analyzed in the literatures, is presented in this paper. Experimental results of an LLC converter prototype are provided to verify the theoretical analysis.

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