A high efficiency isolated DC/DC converter using series connection on secondary side

This paper proposes a new circuit topology for a high efficiency isolated buck-boost DC/DC converter. The proposed converter consists of a high efficiency resonance half-bridge converter and a series converter. This proposed circuit regulates the output voltage by the series converter, which provides only the differential voltage between the input voltage and the output voltage. Therefore, the circuit achieves high efficiency when the input voltage is closed to the nominal input voltage, since only the resonance converter will operate. Experimental results are shown in order to demonstrate the advantages of the proposed converters in comparison with a conventional converter. The experimental results confirmed that the proposed circuit, which converts 48 V input to 12 V, achieves 94.0% maximum efficiency point at the nominal input voltage region.