Compact and low profile power converters are the main business of today’s power industry. A significant volume of a power converter is occupied by the power transformer. This article proposes a unique solution that would make the power converters low profile. Instead of designing a power converter by using a single bulky transformer, the solution proposed is to split the main bulky transformer into a number of low profile transformers. This not only reduces the total weight and volume of the converter but also the total transformer losses. The use of more than one transformer in series reduces the applied voltage on the transformers, which minimizes the required turns ratio and decreases the stress on the secondary rectifiers and filter elements. Moreover, the decrease in the applied voltage reduces the proportional loss per transformer and makes it possible to design a hybrid transformer by combining Litz wire and traces of a printed circuit board. The reduced copper loss and lower heat dissipation per transformer simplify thermal management. An analytical comparison is made between the utilization of a single transformer or a number of transformers. The procedure of splitting a volume of a single transformer into a number of small transformers has been comprehensively discussed. The idea is investigated both experimentally and in computer simulation for an example application of a phase shifted full bridge dc-dc converter. The converter is characterized up to a load power of 2.2 kW at $V_{in} =400\,\,\text{V}_{\mathrm {dc}}$ and $\text{V}_{out} =48\,\,\text{V}_{\mathrm {dc}}$ .To make the approach more practical, the transformers are modeled using the traditional analytical method. The design of the example application using the split transformer approach reduces the total transformer weight by 45%, compared to the traditional approach with a single transformer. The converter also shows good performance with a maximum efficiency of 96%.

中文翻译：

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用于薄型功率转换器的串联混合变压器的建模和表征

紧凑和薄型电源转换器是当今电力行业的主要业务。电源转换器占据了电源转换器的很大一部分。本文提出了一种独特的解决方案，可以使电源转换器变得低调。所提出的解决方案不是通过使用单个笨重的变压器来设计电源转换器，而是将主要笨重的变压器拆分为多个低剖面变压器。这不仅减少了转换器的总重量和体积，而且减少了总变压器损耗。使用一个以上的串联变压器会降低变压器上的施加电压，从而最大限度地减少所需的匝数比并降低次级整流器和滤波器元件上的应力。而且，施加电压的降低降低了每个变压器的比例损耗，并且可以通过将利兹线和印刷电路板的走线相结合来设计混合变压器。每个变压器减少的铜损和更低的散热简化了热管理。在使用单个变压器或多个变压器之间进行分析比较。已经全面讨论了将单个变压器的体积拆分为多个小变压器的过程。对于相移全桥 dc-dc 转换器的示例应用，该想法通过实验和计算机模拟进行了研究。转换器在 $V_{in} =400\,\,\text{V}_{\mathrm {dc}}$ 和 $\text{V}_{out} = 时的负载功率高达 2.2 kW 48\,\,\text{V}_{\mathrm {dc}}$ . 为了使该方法更实用，变压器使用传统的分析方法进行建模。与使用单个变压器的传统方法相比，使用分离式变压器方法的示例应用设计将变压器的总重量减少了 45%。该转换器还表现出良好的性能，最高效率为 96%。