Experimental Characterization of Switching Losses in SiC-based DAB Converters

Accurate determination of switching losses is critical for the design and operation of soft-switched converters such as the Dual Active Bridge (DAB), particularly at high switching frequencies. In these converters, turn-off loss remains a major contributor to overall switching losses. Additionally, low current at the switching instant can result in only partial zero-voltage switching (ZVS) turn-on, leading to further increases in switching losses. Analytical loss-modeling approaches become increasingly complex due to the presence of nonlinear output capacitance, device parasitics, and printed-circuit-board (PCB) layout effects. This paper presents an experimental methodology to accurately characterize switching losses, including turn-off and partial ZVS turn-on losses, across various operating modes of the DAB converter. Using the actual converter setup, the necessary equivalent circuits are identified for loss characterization across different DAB operating modes. The proposed methodology is validated using SPICE-based simulations and experiments conducted on a 40kW SiC-based DAB hardware prototype.