Soft-Switching Bidirectional Three-Level DC-DC Converter with Simple Auxiliary Circuit

This paper suggests a soft-switching bidirectional three-level DC-DC converter with a simple auxiliary circuit. The proposed converter uses auxiliary LC resonant circuits so that the power switches operate under a soft-switching condition. The resonant operation of the LC circuits makes power switches turn on at zero voltage, eliminating the turn-on switching power losses. The proposed converter improves the power efficiency, not using complex power switching circuits, but using simple LC resonant circuits. The operation of the proposed converter is described according to its operation modes. Experimental results for a 1.0 kW prototype are discussed to verify its performance. The proposed converter achieved the power efficiencies of 97.7% in the step-up mode and 97.8% in the step-down mode, respectively, for the rated load condition.