PhD student Furkan Karakaya with Advisor A. Banerjee

Silicon Carbide (SiC) MOSFETs are being widely adopted in the industry as a viable substitute for conventianal power transistors, due to their superior figure-of-merit and compact, efficient power conversion. However, the relatively novel manufacturing technology of these devices raises questions regarding long-term reliability, as SiC devices have been known to suffer from degradation over time, generally manifesting an increased on-state resistance, inductance, or impedance. Measuring device parameters periodically is essential to identify the remaining useful lifetime of a Sic MOSFET. The operating voltage and current levels in kilovolts and kiloamperes presents a challenge, due to the impedance values typically falling in the range of several dozen milliohms.
Our recent design, depicted as version 5 (Figure 1), successfully addresses this challenge and enables reliable device characterization, even during an active converter operation. As shown in Figure 2, the key idea behind the proposed design involves injecting a sinusoidal current in the MHz range, with the resultant voltage being filtered out by custom-engineered

Figure 1. Design enables reliable device characterization, even during an active converter operation.

analog circuitry. Necessary calculations are then performed by the circuit, enabling on-state resistance and

Figure 2. Sinoisoidal current injected in the MHz range with resultant voltage filtered out by custom-engineered analog circuitry.

package inductance to be accurately estimated in the milliohm and nanohenry ranges, respectively. This work was funded by the Office of Naval Research MVDC Risk Reduction program.