Smart Control Scheme for Light-Load Conversion Efficiency Enhancement of Three-Phase Dual Active Bridge DC-DC Converters

Electric vehicles and energy storage systems are developing rapidly, leading to an increasing demand for highpower DC-DC bidirectional power converters. However, these converters often have low conversion efficiency at light loads, resulting in energy wastage. This paper represents a smart control scheme to enhance the light-load conversion efficiency of a Three-Phase Dual Active Bridge (TPDAB) DC-DC converter by dynamically exchanging the single-phase and three-phase modes according to the load conditions. A rigorous loss analysis for the TPDAB converter operated in the three-phase and single-phase modes is derived first. The current point, phase shifts, and arm selection for mode exchange are then designed to optimally control the proposed control scheme. This paper implements a prototype of the TPDAB DC-DC converter, which has a rated high voltage of 380V, a rated low voltage of 48V, and a rated power of 720W. Experimental results show the effectiveness of the proposed smart control scheme, which achieves about 10% conversion efficiency improvement at light loads for the implemented TPDAB DC-DC converter. The proposed smart control scheme can enhance light-load conversion efficiency and achieve energy conservation without hardware reinforcement; therefore, the proposed scheme can be effortlessly integrated into the TPDAB DC-DC converters.