A Reconfigurable Dual-Active-Bridge Resonant Converter Designed for Wide-Load-Range High-Efficiency Operation

Switching loss and conduction loss are two main loss mechanisms in DAB converter and the degree to which they affect the efficiency of DAB converter depends on the chosen power modulation method. In general, no single modulation method will perform well in all operating conditions. In this paper, a hybrid modulation scheme and a new DAB converter topology designed for its realization are presented. The DAB converter is designed to switch between two operation modes: dynamic frequency matching (DFM) and enhanced dual-phase-shift (EDPS) modulation. Under DFM modulation, zero backflow power, zero circulating current, full ZVS are achieved, whereas under EDPS modulation, zero backflow power and full ZVS are achieved. These advantageous features are critical to ensuring high-efficiency operation of DAB converter. The proposed solution is experimentally verified using a 1.5-kW hardware prototype with efficiency exceeding 96% for all output power levels.