Two-three level DAB soft-switching and low current Triple Phase-Shift modulation

This paper explores modulation strategies for 2-3 level Neutral Point Clamped (NPC) Dual Active Bridge (DAB) converters. It focuses on a Triple Phase Shift (TPS) modulation technique and its comparison with other methods such as Minimum Current Stress (MCS), Quasi-Zero Voltage Switching (QZVS), and Single Phase Shift (SPS) modulation. MCS and QZVS are specifically tailored for optimizing 2-3 level NPC DAB converters, with MCS designed to minimize peak current stress and QZVS focused on achieving Zero Voltage Switching (ZVS) for enhanced efficiency while maintaining minimum current stress. Although TPS modulation is well known for its superior performance, in the context of multilevel converters, other strategies offering higher degrees of freedom may yield better results. Nonetheless, TPS still provides notable advantages in this context by reducing RMS current and promoting ZVS, thereby enhancing overall system performance. The study presents a detailed analysis of TPS, including its theoretical background and simulation results. The comparison demonstrates that while TPS maintains competitive performance in terms of reducing RMS current and achieving ZVS, it also simplifies the modulation implementation, presenting a practical and effective alternative to other methods.