Real-time Junction Temperature Monitoring Method for Power Device Based on Two-port Thermal Network

This paper proposed a novel junction temperature monitoring method for power modules based on two-port thermal network, in which the junction temperature T ja and case temperature T ca are taken as virtual external nodes. The transfer relationship between junction temperature T ja and T ca is firstly investigated in Laplace domain, and then be transferred to the time domain. Theoretical analysis shows that the junction temperature could be expressed by using thermal parameters without requiring power loss information, and its effectiveness is verified by simulation and experiment. This method only needs temperature sensor and gets rid of electrical parameter measurement, which is simple and low cost. Besides, the installation of temperature sensor does not cause intrusive change to the original system, and the measurement process does not affect normal operation of device. Thus the implementation of the proposed method brings negligible hardware burden, and provides more flexibility for noninvasive monitoring.