Design and Performance of a 200-kHz All-SiC JFET Current DC-Link Back-to-Back Converter

Silicon carbide (SiC) switching devices have been widely discussed in power electronics due to their desirable properties and are believed to set new standards in efficiency, switching behavior, and power density for state-of-the-art converter systems. In this paper, the design, construction, and performance of a 3-kVA All-SiC current-source converter (CSC), also known as current dc-link back-to-back converter (CLBBC), is presented. CSC topologies have been successfully used for many years for high-power applications. However, for low-power-range converter systems, they could not compete with voltage-source-converter topologies with capacitors in the dc-link, since the link inductor has always been a physically large and heavy component due to the comparatively low switching frequencies of conventional high-blocking-voltage silicon devices. New SiC switches such as the JFET, which are providing simultaneously high-voltage blocking, low switching losses, and low on-state resistance (three times lower compared with Si MOSFET with similar V- I rating), offer new possibilities and enable the implementation of a high switching frequency CLBBC and, thus, reducing size and weight of the dc-link inductor. The prototype CLBBC has been designed specifically for the latest generation 1200-V 6-A SiC JFETs and a target switching frequency of 200 kHz.