Loss Analysis of a High Efficiency GaN and Si Device Mixed Isolated Bidirectional DC-DC Converter

High conversion efficiency is always desired in energy storage device (ESD). In this work a high efficiency GaN and Si device mixed isolated bidirectional dc-dc converter is proposed in the distributed ESD application. To optimize the efficiency of the bidirectional half-bridge push-pull active clamp converter over a wide input/output voltage and load range, it is necessary to accurately predict the dissipated power for each power component so as to identify and properly design the heavily loaded components. This paper describes a universal method to predict the power losses of the converter. Loss models are provided to calculate total component losses using the current and voltage information derived from the steady state inductor current calculator. Details of loss breakdown are given. With the presented converter prototype, a top efficiency of 98.3% and an output power of 1 kW in a wide input/output voltage range is achieved. The loss analysis provides valuable information for designing an efficiency optimized converters in the application.