A Dual‐Transformer Hybrid‐Bridge Resonant Converter With Extended ZVS Capability and Reduced Current Stress

To address the limited zero‐voltage switching (ZVS) operating range, backflow power, and hard‐switching losses of isolated DC–DC converters, a dual‐transformer hybrid‐bridge resonant converter (DTHBRC) is proposed. The proposed topology consists of a primary‐side hybrid bridge, two high‐frequency transformers with unequal turns ratios, and an LC resonant tank. Through this configuration, primary‐side voltage superposition is achieved, and the turns‐ratio coefficient is introduced as an additional design parameter for ZVS boundary optimization. Based on the fundamental harmonic approximation, an equivalent circuit model is established, and analytical expressions for the resonant current, transferred power, and ZVS boundaries are derived. A ‐dependent ZVS‐retention index is introduced to quantify the improvement in ZVS capability. From the primary‐side ZVS boundary conditions, the optimal turns‐ratio coefficient is analytically obtained as , which provides an explicit guideline for transformer turns‐ratio design. In addition, a minimum‐current‐trajectory (MCT) control strategy is employed to align the secondary‐side voltage with the resonant current. Consequently, synchronous rectification is achieved, and both backflow power and conduction loss are reduced. The proposed DTHBRC is validated by simulation and experimental results obtained from a 300 W prototype. ZVS operation is maintained over the full tested load range at and for load levels above 40% of the rated power at . An additional test at 600 W using the same prototype further demonstrates stable operation at a higher power‐transfer level. The measured peak efficiency reaches 96.5%, and improved light‐load efficiency is achieved compared with the dual‐bridge series resonant converter (DBSRC) benchmark.