Optimization design of an isolated DC/DC converter using series compensation on the 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 voltage, since only the resonance converter will operate. The equivalent circuit of the proposed circuit is mentioned to clarify the circuit operation and circuit design. The experimental results confirmed that the proposed circuit, which converts 48-V input to 12-V output, achieves the maximum efficiency of 94.0% at the nominal input voltage region. Besides, the loss analysis is performed to optimize the circuit parameters.