Inverter improvement with SiC MOSFET for HVAC system)

Compared to silicon-based power devices, silicon carbide (SiC) MOSFETs have a higher electric breakdown field, lower intrinsic diode reverse recovery loss, faster switching speed, and capability of handling higher junction temperature. These material properties are favorable, especially, for high efficiency power inverters. In some applications, such as photovoltaic inverters, SiC MOSFETs are popular due to their efficiency, relatively smaller filter size, and higher switching frequency. Fast electric charging systems also use SiC MOSFETs due to their high switching frequency and low losses. The study for low switching application is very rare and the research of system level's benefit needs. In this paper, 10 kW heating, ventilation, and air conditioning (HVAC) systems with 7 kHz switching frequency have been reviewed using a power integrated module with SiC MOSFET as the demo inverter board. This inverter board was tested with a 600 W motor for its functional capability. Also, its switching losses, E-on and E-off, were measured and these were used for measurement-based loss simulation. Finally, through a thermal comparison between Si IGBT-based inverter with liquid cooling and SiC MOSFET-based inverter with forced air cooling, system benefits of SiC MOSFET-based modules were evaluated.