Fundamental study on control strategies to increase efficiency of dual active bridge DC-DC converter

The dual-active-bridge (DAB) topology is ideally suited for bidirectional power transfer. However, the zero-voltage switching (ZVS) range of this topology is limited. Operating in ZVS mode can increase low range power transfer. This paper revised and simplified calculation of ZVS range for single pulse-width modulation (SPWM) and dual pulse-width modulation (DPWM) controls, and power transfer for different winding ratio. These control strategies are compared, combined, and manipulated by three variables: the phase shift between the primary and secondary transformer voltages, the primary voltage width, and secondary voltage width. Combination of these control strategies can reduce the power loss especially in lower range power transfer. A 6 kW, 40 kHz bidirectional isolated dc-dc converter between was simulated to validate the theoretical ZVS range and power transfer.