Dynamic junction temperature estimation via built-in negative thermal coefficient (NTC) thermistor in high power IGBT modules

The junction temperature is closely related to the safe operation and reliability of the insulated gate bipolar transistor (IGBT) modules and the power conversion system. In recent years, an increasing number of researchers are dedicating to the study of online junction temperature extraction method, which is essential for the aging estimation, health management and reliability assessment for the module and the system. In this paper, a dynamic junction temperature estimation method using the built-in negative thermal coefficient (NTC) thermistor in high power IGBT modules with transient thermal model is presented. A two-order thermal model is built to accurately describe the transient impedance between the chip and the built-in thermistor, which is verified by the experimental results. Then by employing the power loss on the module and the NTC temperature, junction temperature can be extract using the proposed method. The experimental results show that the proposed method is effective to estimate the dynamic junction temperature under the situation of load variation and demonstrate its advantages on conventional method.