SILICON CARBIDE FOR NEXT GENERATION VEHICULAR POWER CONVERTERS

Several power converters are presently under development for the US Army TARDEC using all Silicon Carbide (SiC) devices for the power switches. Power modules have recently become available which incorporate multiple SiC devices for both the active and passive switches. Modules fabricated by 2 different vendors (Powerex and MS Kennedy) in a standard half H-Bridge configuration using the same type and number of devices internally (Cree 1200 Volt/20 A DMOSFETs and 1200 Volt/10A SBD) have been obtained and tested. This paper will summarize the main test results including the comparison of the conduction losses, switching losses, switching capability, thermal characteristics, gate drive approach, and physical characteristics (mass/dimensions). As expected, most of the characteristics were very similar between the 2 modules and had reasonable scaling from the individual device characteristics. The differences in the internal connections for the modules result in some differences primarily in the switching characteristics. In addition, there are some differences in the heat transfer characteristics based on the size and material choice differences. A description will be provided of how these modules will be used in the 2 converters being fabricated along with providing the test data. The converters being built are both rated for 30 kW with nominal 300 Volt batteries for the input. One converter provides 28 Volt DC output and the other 50/60 Hz AC output. In addition to meeting the size constraints for fitting into vehicles, the power converters are also being designed to operate from higher temperature coolant (90-100 °C inlet).