Estimating the junction temperature of CIPOS(TM) IPMs using their case temperature and thermistor’s resistance

Abstract:
This paper presents a method to estimate the junction temperature (TJ) of the CIPOS(TM) IPMs using the substrate case temperature (Tc) and the negative temperature coefficient (NTC) thermistor’s temperature. Considering the IPM’s mounting structure on the system’s printed circuit board (PCB), measuring the junction temperature directly is rarely possible. Therefore, being able to estimate the junction temperature without direct measurement is very helpful in reducing time and cost while creating and developing a new system design. This paper describes how to estimate the junction temperature, without directly measuring TJ, through simulation and experiment results. These results were obtained under different cooling conditions that affect the correlation between the junction temperature and the thermistor’s resistance.