双侧零回流功率、最小环流电流及宽范围ZVS的优化与调制——基于宽电压增益五电平NPC-DAB谐振变换器

The neutral-point-clamped (NPC) structures are useful for high-voltage and high-power applications. However, with conventional and unoptimized modulation schemes, NPC-based converters often suffer from high backflow power and low efficiency at wide-voltage gains and light load levels. This article proposes an optimized asymmetric-phase shift modulation strategy, which can achieve complete elimination of the backflow power in transformer’s both sides, wide-range zero-voltage switching (ZVS) for all switches, and near minimum effective current, in a five-level NPC dual-active-bridge resonant converter (5L-NPC-DABRC), thereby simultaneously reducing the switching and conduction power losses. Eventually, the proposed topology and its optimized modulation scheme are verified experimentally in a 600-W laboratory prototype, demonstrating excellent performance throughout the entire power range. By comparing with existing modulation strategies, the proposed method is able to achieve higher efficiencies at different power levels.