SiC JFET has been an attractive device for the converter construction due to its superior switching performance and high temperature operation capability. But the shoot-through protection remains a challenge due to the limited knowledge and normally-on characteristics of this device. This paper presents a novel shoot-through protection approach. A bi-directional switch which consists of an IGBT and a relay is embedded into the dclink and then the shoot-through failure can be detected and cleared regardless the device type used in the converter. Therefore it is suitable for the converter built with SiC JFETs. The protection mechanism and the corresponding circuit design are described in details. The proposed protection circuit is first tested in a phase leg setup with MOSFET and then implemented in an ac-ac converter system using SiC JFETs. The experiment results verify the feasibility of the proposed protection approach.
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