Fundamental Duty Modulation of Dual-Active-Bridge Converter for Wide-Range Operation

This paper proposed a modulation scheme for the dual-active-bridge (DAB) converter to reduce rms current in wide-range operating conditions. The operating principle of the proposed fundamental duty modulation (FDM) is formulated based on the fundamental component analysis of the DAB converter. By modulating the PWM signals in the fundamental component domain, the optimal operation is implemented with a simple controller structure not requiring an operating mode classification, offline calculation, or current information. Operating characteristics including rms current level and ZVS characteristics are analyzed to compare loss breakdowns of the proposed scheme to those of recent related works. The proposed FDM achieves high efficiency under wide operation conditions due to reduced conduction level and wide ZVS range. Experimental results are obtained under various voltage gain and load conditions to confirm the operation of the proposed modulation scheme. A thorough experimental comparison with other sophisticated modulation schemes has verified the efficiency improvement of FDM.