Dual Active Bridge (DAB) DC–DC converters are commonly used in high-power isolated systems, including on-board and off-board electric vehicle chargers, because of their inherent bidirectional power transfer capability and compact design. However, as charging power levels and efficiency targets continue to rise in modern EV infrastructures, the associated increase in semiconductor losses and device temperatures makes thermal performance a critical design concern. Despite the advantages, traditional DAB converters with single-phase shift (SPS) control tend to incur considerable switching losses, especially at high power levels, which can raise semiconductor junction temperatures. In particular, the lack of a detailed, application-oriented comparison between the thermal loss behavior of conventional DAB converters and resonant-assisted variants under realistic EV charging conditions limits designers’ ability to select the most thermally efficient topology. For this reason, the power-loss characteristics and thermal response of a conventional DAB converter, related to its switches, are evaluated and compared with those of an LLL-tank-assisted DAB topology. The two converter topologies are modeled in MATLAB/Simulink and PLECS and tested under identical operating conditions, including power level and control method, so that the results can be directly compared. Semiconductor losses are then estimated by considering both conduction and switching components, with switching energy values taken from the IGBT manufacturer’s datasheet. Junction temperature is then estimated through a steady-state thermal resistance model that relates total power dissipation to ambient conditions. The influence of the LLL resonant tank on converter current profiles and thermal stress is analyzed. Simulation results show that introducing the LLL resonant tank reduces switching and conduction losses, thereby lowering the junction temperature of the power semiconductor devices compared with the conventional DAB converter. This improvement is achieved without altering the original SPS control approach. The outcomes of this work offer valuable guidance for thermally optimized design of high-power isolated DC–DC converters used in electric vehicle charging systems, bridging an important gap between efficiency-oriented analysis and comprehensive thermal loss evaluation for practical EV charger applications.
This work presents a systematic comparative thermal loss analysis of a Dual Active Bridge (DAB) converter operating with and without an LLL resonant tank, specifically for high-power EV charger applications. Unlike prior studies that primarily focus on efficiency enhancement or soft-switching performance of resonant-assisted DAB topologies, this study provides a detailed device-level evaluation of thermal and loss distribution under identical operating conditions. The proposed comparison framework quantifies conduction and switching losses and the resulting impact on system-level thermal management requirements. This approach enables a clearer understanding of the trade-offs between conventional DAB and LLL-assisted configurations in terms of efficiency, thermal performance, and practical constraints for EV charger implementation.