Hybrid Phase-Shift Modulation Strategy for Dual Active Bridge Converters to Improve Full Power Range Efficiency

To the purpose of improving the dual active bridge converter effectiveness in the full power range, a hybrid phase-shift (HPS) modulation strategy is proposed in this paper, which combines the asymmetric duty (ADM) modulation strategy with the symmetric duty (SDM) modulation strategy in different combinations for different power ranges. Firstly, the typical waveforms of HPS at light load are generated by ADM and SDM combination, followed by the typical waveforms of HPS at medium load as well as heavy load by ADM and ADM combination. Secondly, the inductor current peak-to-peak value as well as the transmitted power for both modes are obtained based on the constraints of the degrees of freedom. The optimal solution of the control degrees of freedom is solved by applying the Karush-Kuhn-Tucker (KKT) condition with the peak-peak value of inductor current as the optimisation objective, and the direct power control strategy based on HPS is proposed. In conclusion, an experimental platform with a rated power of 300 W is built, and the preliminary outcome validates that the HPS modulation strategy can effectively improve the efficiency of the entire power range DAB converter.