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FIGURE 2: V-I CURVE COMPARISON FOR A Si IGBT AND SiC MOSFET (SOURCE: STMICROELECTRONICS)
Electrothermal
simulation
To compare SiC MOSFETs and Si IGBTs when they operate in a typical indus- trial drive application, an electrother- mal simulation is the better choice. ST performed such a simulation using its proprietary software tool, PowerStudio. The software provides comprehensive power and thermal analysis to predict the device performance, reducing the time to market. The tool also helps in selecting the proper device to fit the application mission profile.
PowerStudio is based on a precise built-in electrical and thermal model for each device. Thanks to an iterative calculation that considers the self- heating effects, it provides a highly accurate estimation of the power loss
requires VGS = 18 V to achieve an excellent RDS(on), it can provide much better static performance than the Si-based IGBT, significantly reducing conduction loss.
The two devices have also been analyzed from the dynamic point of view, using a double-pulse test. The aim of this test was to provide dynamic loss measure during turn-on and turn-off conditions. The obtained results showed that the SiC MOSFET exhibits approximately 50% lower turn-on and turn-off energies than the Si IGBT across the entire current range, even under the 5-V/ns condition. At 50 V/ns, the SiC MOSFET reduces losses even more. IGBTs cannot reach that high commutation speed.
and the junction and case temperatures. Based on the elec- trothermal simulations it conducted with PowerStudio, ST proved that much better energy efficiency can be achieved using SiC MOSFETs, thus reducing the thermal requirements of any heatsinks with attendant benefits to weight, space, and costs. The SiC MOSFET solution offers much lower overall power loss compared with the Si IGBT for static and dynamic conditions and for both the switch and the diode.
This article was originally published on Power Electronics News on March 26, 2021.
Stefano Lovati
is a technical writer for Power Electronics News and EEWeb.
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