Novel Burst-mode Control Strategy for Dual Active Bridge Converters to Improve Light-load Efficiency

The dual active bridge (DAB) converter is widely used in many applications. Nonetheless, efficiency degrades significantly under light load conditions due to high switching and conduction losses. Burst mode control techniques have been widely employed to increase efficiency under light load conditions. However, in previous research, the burst mode was applied to the DAB converter without taking into account optimal operating conditions. The optimal burst mode control for the light load condition region is proposed in this paper. The DAB converter is designed to operate in the ZVS condition regions and at a minimum backflow power condition. Therefore, the switching loss and conduction loss are simultaneously minimized, significantly improving the light load efficiency. The 4 kW DAB converter prototype is built to verify the analysis. The experiment results show an approximately 30% increase in efficiency when compared with the conventional single phase-shift modulation (SPSM) method at very light load conditions.