Analysis and optimization of LLC resonant converter with a novel over-current protection circuit

A novel over-current protection (OCP) method for a LLC resonant converter has been proposed in this paper. This method is very attractive for its inherent current limit ability, especially under short-circuit condition. Combined with the frequency increasing method, good current limit features can be achieved. Compared to the conventional LLC resonant converter with frequency increasing method, LLC with the proposed OCP method can reduce the maximum frequency to an acceptable value. Detailed theoretical analysis and optimization design considerations have been presented. An experimental prototype converter based on the proposed method has been built up to verify the theoretical analysis. Experimental results meet the theoretical analysis very well.