An IGBT Driver Concept with Integrated Real-Time Junction Temperature Measurement

Inhalt:
This paper presents an IGBT driver concept that is suitable to measure the junction temperature of a conventional IGBT power module during inverter operation. Thereby the temperature of the internal gate resistor is determined by superimposing the negative gate voltage with a highfrequency, sinusoidal identification signal. New aspects are the parallel feeding in of the identification voltage into an existing IGBT driver circuit and the generation of an ADC compatible sensor voltage using a fast rectifier and an offset compensation. The driver concept is easy to realize and enables junction temperature measurement without affecting the IGBT switching behavior and the regular inverter operation. On the basis of the theoretical backgrounds this paper presents the subsystems of the driver concept and discusses its technical feasibility. First measurement results found the remaining noise of the temperature measurement to be smaller than ± 1 °C. In the introduction existing approaches to measure the junction temperature are reviewed and valued regarding their usability during inverter operation.