DAB with Switched Inductor (DAB-SI) for Reduced Effective Currents at Light-load Operation

The Dual Active Bridge Converter topology is widely recognized for its high power density in high-power applications, enabling soft switching and achieving high efficiencies in both buck and boost operation modes. However, under conventional phase-shift modulation, operation at light or no load results in hard-switching and high effective currents, leading to increased overall losses, one of its main drawbacks. These issues have been primarily addressed by implementing complex modulation strategies, leveraging from the multiple degrees of freedom in the control of the converter power, particularly the inner and outer shift angles of its bridges. Contrary to the traditional approach, this work proposes the modulation of the series inductance of the DAB converter by implementing a switched inductor, aiming for a simplified modulation strategy. The proposed method effectively achieves zero current under no-load conditions and significantly reduces effective currents at light loads compared to the traditional phase-shift modulation approach. Although an in-depth comparison with other modulation schemes is required, this work represents a stepping stone in the analysis of the topology and the comprehension of its trade-offs.