An Accurate On‐State Voltage Measurement Circuit for Chip‐Level Junction Temperature Monitoring of Press‐Pack IGBT

Junction temperature monitoring for multiple chips inside a press‐pack insulated gate bipolar transistor (PP IGBT) is essential to evaluate the temperature uniformity and operational reliability of the device. The low‐current collector–emitter on‐state voltage ( V ce ) is the most promising method for chip‐level junction temperature monitoring owing to its high measurement accuracy. However, for conventional on‐state voltage measurement circuits (OVMCs), the temperature difference occurs between the dual diodes during long‐term operation, leading to errors in the online V ce measurement. This paper proposes a novel OVMC for accurately extracting V ce online. By adopting a power‐balanced differential diode topology, the temperature of the dual diodes is equalised, thereby minimising the error of V ce measurement. Comparative experiments with the conventional circuits indicate that the proposed OVMC reduces the temperature difference between the dual diodes from approximately 5°C in the conventional circuits to 0.3°C, and the maximum V ce measurement error is within 1 mV. Furthermore, the proposed circuit is applied to the Buck operating condition to monitor the junction temperature of chips inside the PP IGBT. The maximum temperature monitoring error is only 2.0°C compared with that of the contact thermocouple measurements, demonstrating the accuracy of the proposed OVMC for online junction temperature monitoring.