Online Monitoring System of Power Semiconductor Devices Based on Frequency Domain Thermal Impedance and On-State Voltage Drop

Considering the widespread application of grid-connected inverters in distributed renewable energy generation, ensuring their safe and reliable operation necessitates accurate and real-time online measurement of the state of power semiconductor devices within these inverters. This paper proposes a monitoring scheme for power semiconductor devices based on the frequency domain thermal impedance model and the on-state voltage drop V
CE(on)
of power semiconductor devices. It first introduces the frequency domain thermal impedance model of power semiconductor devices, and the three-dimensional relationship between conduction current, junction temperature, and V
CE(on)
, and then proposes a junction temperature estimation scheme that combines these elements. Finally, a power semiconductor device state online monitoring system is designed and built, with experiments validating the accuracy of the estimation scheme. Through this monitoring platform, real-time and accurate measurements of V
CE(on)
, junction temperature, and thermal impedance parameters are achievable, laying the foundation for the extraction of device reliability indicators.