Efficient dc–dc power-conversion with wide-span voltage-regulation is crucial to a sustainable and robust power electronics system. Dual-active-bridge (DAB) offers straight-forward regulation and its transformer enables voltage step-up/down required for many applications, such as battery chargers and bus converters for dc distribution systems. However, losing soft-switching at light loads or when operating at voltage gains far from the turns ratio severely degrades the efficiency of DAB, especially at high switching frequencies. In this article, we demonstrate an enhanced DAB (E-DAB) topology which employs an adjustable-tap transformer to extend the soft-switching over wider voltage gains and increase the power-transfer capability. By a proper tap adjustment and with single phase-shift modulation, the proposed gallium nitride (GaN)-based converter achieved a peak efficiency of 97.4% with an overall efficiency greater than a conventional DAB for voltage gains of up to 2.8 times higher. Employing a quasi-planar matrix transformer with integrated leakage inductance at 300 kHz allowed for an extremely high power density of 10 kW/l (7.5 kW/l with cooling). The tapped transformer did not incur extra losses to the topology. The gain versus power-transfer characteristic for soft-switching operation was derived for the E-DAB and its improvement in efficiency was experimentally verified over a wide power range.

中文翻译：

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使用可调抽头高频变压器增强 DAB 以保持效率

具有宽跨度电压调节的高效 DC-DC 电源转换对于可持续和强大的电力电子系统至关重要。双有源桥 (DAB) 提供直接调节，其变压器可实现许多应用所需的升压/降压，例如电池充电器和直流配电系统的总线转换器。然而，在轻负载下或在远离匝数比的电压增益下运行时失去软开关会严重降低 DAB 的效率，尤其是在高开关频率下。在本文中，我们展示了一种增强型 DAB (E-DAB) 拓扑，该拓扑采用可调抽头变压器来扩展更宽电压增益上的软开关并提高功率传输能力。通过适当的抽头调整和单相移调制，提议的基于氮化镓 (GaN) 的转换器实现了 97.4% 的峰值效率，整体效率高于传统 DAB，电压增益高达 2.8 倍。采用具有 300 kHz 集成漏感的准平面矩阵变压器可实现 10 kW/l 的极高功率密度（7.5 kW/l，带冷却）。抽头变压器不会给拓扑带来额外的损耗。为 E-DAB 导出了软开关操作的增益与功率传输特性，并在很宽的功率范围内通过实验验证了其效率的提高。采用具有 300 kHz 集成漏感的准平面矩阵变压器可实现 10 kW/l（7.5 kW/l 冷却）的极高功率密度。抽头变压器不会给拓扑带来额外的损耗。为 E-DAB 导出了软开关操作的增益与功率传输特性，并在很宽的功率范围内通过实验验证了其效率的提高。采用具有 300 kHz 集成漏感的准平面矩阵变压器可实现 10 kW/l 的极高功率密度（7.5 kW/l，带冷却）。抽头变压器不会给拓扑结构带来额外的损耗。为 E-DAB 导出了软开关操作的增益与功率传输特性，并在很宽的功率范围内通过实验验证了其效率的提高。