Design of a GaN-based Series Resonant Dual Active Bridge DC-DC converter for EV Charging Application

Dual active bridge (DAB) and series resonant dual active bridge (SRDAB) DC-DC converters are preferred for electric vehicle (EV) charging applications due to their narrow frequency variation and full bidirectional power flow capability. While DAB converters can introduce higher-order harmonics in the high-frequency link current, leading to increased conduction losses, SRDAB converters offer several advantages. These include lower RMS current, reduced turn-off switching loss, and lower harmonic content in the link current, which enhances efficiency during high-frequency operation. This paper presents the design and implementation of a high-frequency SRDAB converter using GaN HEMTs for EV charging applications. The converter operates with an input voltage of approximately 400 V, and its output voltage ranges from 280 V to 460 V, delivering a maximum power of 6.6 kW. Operating within a frequency range of 400 kHz to 600 kHz, the converter uses frequency variation to extend the zero voltage switching (ZVS) range. Commercially available 650 V GaN HEMTs are employed to optimize both conduction and switching performance. A hardware prototype was designed, fabricated, and tested at full power across various output voltages.