An inverter constructed with off-the-shelf silicon-carbide power modules transfers 99% of its input energy to the motors it drives, say designers at the Future Renewable Electric Energy Distribution and Management (FREEDM) Systems Center at NC State. This is about 2% higher than the best silicon-based inverters under normal conditions.
The new SiC-based inverter is also smaller and lighter than versions using silicon power semiconductors. It hits a power density of 12.1 kW/L – close to the U.S. DOE goal of developing inverters at 13.4 kW/L by 2020. For comparison, electric vehicles made in 2010 could do only 4.1 kW/L.
Designers also say the new inverter is more effective at dissipating heat than previous versions. This could lead to the creation of air-cooled inverters, eliminating bulky and heavy liquid cooling systems. They expect to eventually make an air-cooled inverter up to 35 kW using the new module, for use in motorcycles, hybrid vehicles and scooters. The current SiC inverter prototype was designed to hit 55 kW – enough power for a hybrid vehicle. The researchers are now in the process of scaling it up to 100 kW – large enough for a fully electric vehicle – using off-the-shelf components.
Researchers described their work in a paper delivered at the recent IEEE Energy Conversion Congress and Exposition (ECCE) conference, “Design Methodology for a Planarized High Power Density EV/HEV Traction Drive using SiC Power Modules.”