Insulated gate bipolar transistor (IGBT) modules are the most critical components of modular multilevel converters (MMCs). However, they are subjected to repetitive thermo-mechanical stress caused by thermal cycles on different materials, which can easily lead to failures in the solder layers. Moreover, when MMCs work at high power factor, the IGBT modules have severely uneven temperature distribution due to the inherent dc-bias in arm currents. Some chips are much hotter than others. These hot spots significantly reduce the lifetime of the whole module. This article proposes an optimized and low-cost air-cooling system dedicated to the application of MMC. Uniquely designed O-shaped heat pipes are embedded on the heatsink to add another thermal path without extra fans and fins. The unique shape and layout of heat pipes can minimize the hot spots temperature. The operating principle and power loss of MMC are analyzed first. Then, 3-D finite element (FE) simulation is performed in ANSYS 19.2. Nine modified air-cooling heatsinks with embedded heat pipes are proposed and compared. Finally, the optimal one and a conventional air-cooling heatsink are fabricated for experimental evaluation. The comparative experiment results show that the optimized cooling system is superior over the conventional one by 20% lower in the hot spot temperature.

中文翻译：

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使用嵌入式 O 形热管的 MMC 中 IGBT 模块的风冷系统优化

绝缘栅双极晶体管 (IGBT) 模块是模块化多电平转换器 (MMC) 中最关键的组件。然而，它们受到不同材料热循环引起的重复热机械应力，这很容易导致焊层失效。此外，当MMCs在高功率因数下工作时，由于臂电流中固有的直流偏置，IGBT模块的温度分布严重不均匀。有些芯片比其他芯片要热得多。这些热点显着缩短了整个模块的使用寿命。本文针对MMC的应用提出了一种优化的低成本风冷系统。独特设计的 O 形热管嵌入散热器上，无需额外的风扇和鳍片即可增加另一条热路径。独特的热管形状和布局可以最大限度地降低热点温度。首先分析MMC的工作原理和功率损耗。然后，在 ANSYS 19.2 中执行 3-D 有限元 (FE) 模拟。提出并比较了九种带有嵌入式热管的改进型风冷散热器。最后，制造了最佳的和传统的风冷散热器用于实验评估。对比实验结果表明，优化后的冷却系统在热点温度上比传统冷却系统优越20%。最佳的一个和一个传统的风冷散热器被制造用于实验评估。对比实验结果表明，优化后的冷却系统在热点温度上比传统冷却系统优越20%。最佳的一个和一个传统的风冷散热器被制造用于实验评估。对比实验结果表明，优化后的冷却系统在热点温度上比传统冷却系统优越20%。