A Converter-Level Junction Temperature Monitoring Method for IGBT Based on the Turn-OFF Gate Electric Quantities

The junction temperature is a significant indicator for evaluating the reliability of insulated gate bipolar transistors (IGBTs). In this article, in order to realize noninvasive and simple temperature monitoring, the gate electric quantities are adopted as the thermo-sensitive electrical parameter (TSEP), and the proposed method can realize high sensitivity for monitoring junction temperature of IGBTs. First, the gate electric quantities is adopted and studied as the TSEP. The temperature relationship and sensitivity of the gate electric quantities are analyzed. And then, a sampling circuit of the gate current has been designed with a current transformer (CT) in gate-driver circuit. In addition, the thermo-sensitivity enhanced method of the measured results is proposed by regulating the output resistor of CT. Finally, the inverter experimental platform is developed to verify the correctness of theoretical analysis. Compared with conventional schemes, the proposed gate electric quantities method can achieve higher accuracy and sensitivity for monitoring junction temperature of IGBTs from the gate-drive side. In addition, the sampling circuit is simple and easy to be integrated on the gate-drive circuit.