Deadband Effect and Accurate ZVS Boundaries of GaN-Based Dual-Active-Bridge Converters with Multiple-Phase-Shift Control

Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) are promising for the next-generation power switching applications due to their low on-resistance, high-frequency operation, and small gate capacitances, which are essential for the power density and efficiency improvement. However, with the increase of the switching frequency, the deadband effect will become a challenging issue for the high-efficiency converter design over a wide operation range. In this article, a comprehensive theoretical analysis and experimental verification of the deadband effect in the GaN-based dual-active-bridge (DAB) converters with multiple-phase-shift (MPS) control is presented. First, resonant transitions for various switching conditions with different initial currents by using MPS controls are discussed, and the effect of the stray capacitance of GaN HEMTs is analyzed. On this basis, the accurate boundaries among zero-voltage switching (ZVS), partial ZVS, and hard switching with MPS control can be obtained. A deadband compensation strategy is proposed by considering different switching conditions. Finally, a DAB prototype based on GaN HEMTs was built, and main experimental results were provided to verify the effectiveness of the proposed resonant transition analysis, ZVS boundaries, and the deadband compensation strategy.