Design and Implementation of Online IGBT Junction Temperature Measurement System for Practical Application in DC/AC Converter

This paper presents the design and implementation of a system for real-time measurement and estimation of Insulated Gate Bipolar Transistor (IGBT) junction temperature. A specialized circuit is developed to accurately discern the turn-off delay time of the IGBT. Through experimentation, the relationship between the turn-off delay time and junction temperature, switch current, and switch voltage is characterized. Further-more, the system's offline junction temperature measurement accuracy is validated using dual-pulse testing. Based on RC ladder network, comprehensive models for device losses and thermal resistances are established. Existing IGBT junction temperature monitoring systems often lack real-time verification under continuous operation scenarios. To address this, we construct a dedicated testing platform based on Fuji's half-bridge module 2MBI300XNA120-50, facilitating real-time monitoring of device junction temperature within each switching cycle. The efficacy of the proposed junction temperature measurement and estimation system is evaluated through comparative analysis.