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 (T_J) and the load current (I_L) of IGBTs using a momentary high-Z gate driving (MHZGD) from the output voltage (V_OUT) of the gate driver is proposed, which can be integrated into the gate driver ICs. T_J is estimated from V_OUT difference during and after the MHZGD period, and I_L is estimated from V_OUT during MHZGD. In the 110 switching measurements at 11 different T_J's from 25^°C to 125^°C and 10 different I_L's from 12.5A to 80A for each of the three IGBTs,T_J and I_L 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,T_J and I_L estimation errors in a parameter determination method with small error are +4.9^°C/-8.1^°C and +1.0A/-1.8A, respectively.