A comparative evaluation of new silicon carbide diodes and state-of-the-art silicon diodes for power electronic applications

Recent progress in silicon carbide (SiC) material has made it feasible to build power devices of reasonable current density. This paper presents recent results including a comparison with state-of-the-art silicon diodes. Switching losses for two silicon diodes (a fast diode, 600 V, 50 A, 60 ns Trr), an ultra-fast silicon diode (600 V, 50 A, 23 ns Trr) and a 4H-SiC diode (600 V, 50 A) are compared. The effect of diode reverse recovery on the turn-on losses of a fast WARP ^TM IGBT are studied both at room temperature and at 150°C. At room temperature, SiC diodes allow a reduction of IGBT turn-on losses by 25% compared to ultra-fast silicon diodes and by 70% compared to fast silicon diodes. At 150°C junction temperature, SiC diodes allow a turn-on loss reduction of 35% and 85% compared to ultra-fast and fast silicon diodes respectively. The silicon and SiC diodes are used in a boost power converter with the WARP^TM IGBT to assess the overall effect of SiC diodes on the power converter characteristics. Efficiency measurements at light load (100 W) and full load (500 W) are reported. Although SiC diodes exhibit very low switching losses, their high conduction losses due to the high forward drop dominate the overall losses, hence reducing the overall efficiency. Since this is an ongoing development, it is expected that future prototypes will have improved forward characteristics