Driver Integrated Online Rds-on Monitoring Method for SiC Power Converters

The degradation or failure of SiC MOSFETs is a crucial factor determining the converter reliability. The failure mechanism can be grouped into chip-related failures or package-related failures. The chip-related failures are mostly related to internal device stress under high electric field and high-temperature conditions, such as those near the gate oxide interface. Package-related failures are related to the chip and package interface, caused by different thermal expansion rates. Monitoring the device conditions online can infer the health status of the converter, predict the remaining lifetime, or schedule maintenance effectively. This paper focuses on online monitoring of the R
ds_on
. A novel gate driver integrated on-state voltage measurement (OVM) and junction temperature measurement (OTM) circuits are developed, which can be used to measure the device R
ds_on
and junction temperature in each switching cycle while not interfering with the normal converter operation and the overcurrent protection. The concept is verified experimentally in a 10kW SiC buck converter and a 50kW DC-AC inverter.