Hybrid dc switches have better performance with regard to energy conservation and less arc erosion than conventional semiconductor switches and mechanical switches. A novel hybrid dc switch based on a SiC-MOSFET is developed, and it accomplishes arc-less commutation if the current is below a threshold value, which is mainly determined by the boiling voltage of its contact material. However, as it is difficult for common contact materials to have both a low ON-state contact resistance and high boiling voltage, optimization of the contact materials is necessary to further decrease the ON-state contact resistance and improve the arc-less commutation characteristics of hybrid dc switches. New-type Cu-W clad contacts are proposed in this article by brazing tungsten top layers on copper bulks. The performance of the Cu-W clad contacts with the tungsten top layers of different thickness is evaluated by comparing their ON-state contact resistance and the threshold current of arc-less commutation with those of copper contacts and tungsten contacts under dc current ranging from 100 to 400 A. The results of the experiments show that the Cu-W clad contacts with the tungsten top layers of 1 mm thickness are the most suitable for arc-less hybrid dc switches because of their low ON-state contact resistance and largest threshold current of arc-less commutation.

中文翻译：

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混合直流开关中Cu-W包层接触材料的导通状态接触电阻和减弧换向特性

与传统的半导体开关和机械开关相比，混合式直流开关在节能方面具有更好的性能，并且电弧腐蚀更少。开发了一种新型的基于SiC-MOSFET的混合直流开关，如果电流低于阈值（主要由其接触材料的沸腾电压决定），该开关可实现无电弧换相。然而，由于普通的接触材料难以同时具有低的导通状态接触电阻和高的沸腾电压，因此必须对接触材料进行优化以进一步降低导通状态的接触电阻并改善无触点电弧的换向特性。混合直流开关。本文提出了通过在铜块上钎焊钨顶层来形成新型的Cu-W包层触头。