Junction Temperature Measurement Based on the Internal Gate Resistance for a Wide Range of Power Semiconductors

This paper presents research results on the junction temperature measurement via the internal gate resistance in converter operation for IGBTs and its applicability to other types of active power semiconductors. A junction temperature monitor has been developed to determine the value of the temperature-dependent internal gate resistance by using a sinusoidal voltage superimposed on the gate voltage at the resonance frequency. The device enables a simple and robust junction temperature measurement in inverter operation, which is in excellent agreement with an infrared reference measurement. The method's applicability to semiconductors other than Si-IGBTs, such as SiC-MOSFETs, JFETs, and GaN devices, is verified by gate impedance measurements using a network analyzer. The gate impedance's quality factor is decisive. Other temperature-sensitive electrical parameters (TSEPs) related to the switching behavior depend on the internal gate resistance. Therefore, the findings presented are relevant for many junction temperature measurement methods.