Internal Power Loss Modeling and Efficiency Evaluation of Full-Bridge DC–DC Converters Based on Load-Current-Dependent Loss Coefficients

In this paper, a theoretical methodology is proposed for the systematic analysis of the power conversion efficiency of a full-bridge converter. Using the steady-state analysis results derived from the equivalent circuit, we introduced the concept of “loss coefficients” by categorizing parameters based on their correlation with load power and current. In particular, the loss factors for key components were organized in a tabular format according to their respective contributions to the load current. Furthermore, this study presented the contribution of the rectifier’s internal loss and overall power conversion efficiency through graphical representations to facilitate intuitive understanding. Finally, to verify the validity of the efficiency analysis incorporating the proposed loss factors, a loss and efficiency analysis was conducted on a 300 W-class full-bridge converter, and the results were compared with measured data from an experimental prototype. The results demonstrate that, at maximum load power, the discrepancy between the experimental and theoretical power conversion efficiency values ranged from a maximum of 1%. Consequently, it was confirmed that the proposed analysis method based on effective currents of key components and loss coefficients reflecting internal parasitic elements provides a valid approach for characterizing internal power loss and conversion efficiency relative to load current.