Abstract: For bidirectional DC-DC converters in energy storage, automotive, and DC microgrid applications, this work develops a SiC-based steady-state loss model covering conduction, switching, Coss/diode, magnetic, and auxiliary losses. An electro-thermal co-iteration scheme and a compact thermal-network equivalence are proposed. Using a DAB prototype and double-pulse tests, we perform parameter identification and calibrate the model. Results show that, under representative operating conditions, the predicted efficiency and temperature deviate from measurements by about 10%, meeting thermal-margin and real-time requirements and demonstrating strong potential for engineering deployment.