Estimation of Both Junction Temperature and Load Current of IGBTs from Output Voltage of Gate Driver

Abstract

For the online condition monitoring of IGBTs, a new estimation method of both the junction temperature (TJ) and the load current (IL) of IGBTs using a momentary high-Z gate driving (MHZGD) from the output voltage (VOUT) of the gate driver is proposed, which can be integrated into the gate driver ICs. TJ is estimated from VOUT difference during and after the MHZGD period, and IL is estimated from VOUT during MHZGD. In the 110 switching measurements at 11 different TJ's from 25 °C to 125 °C and 10 different IL's from 12.5 A to 80 A for each of the three IGBTs, TJ and IL estimation errors in a low test cost parameter determination method are + 4.9 °C / − 8.4 °C and + 1.1 A / − 4.3 A, respectively. In contrast, TJ and IL estimation errors in a parameter determination method with small error are + 4.9 °C / − 8.1 °C and + 1.0 A / − 1.8 A, respectively.