IGBT Junction Temperature Estimation via Gate Voltage Plateau Sensing
C. H. van der Broeck, A. Gospodinov, R. W. De Doncker, IEEE Transactions on Industry Applications, 2018
A method for in-situ high-bandwidth junction temperature estimation of Insulated Gate Bipolar Transistors (IGBTs) is introduced. The method is based on the acquisition of the gate voltage plateau during turnon. It can be related to the junction temperature at any known device current, that can be effectively approximated using existing phase current measurements. This allows fast over-temperature protection of the power device or even active thermal cycle reduction via thermal control. This paper discusses, firstly, the physical mechanisms leading to the temperature sensitivity of the gate voltage plateau. Secondly, a rigorous sensitivity analysis of the gate voltage plateau is conducted. It allows to determine the maximal estimation error and provides information about the suitability of this method for various devices and applications. Finally, a sensing circuitry is presented, that allows accurate gate voltage plateau sensing every switching period as well as an easy integration into the gate driver. The performance of the proposed method is experimentally demonstrated with the sensing circuitry on a double pulse test bench over a wide operation range.