Accounting for Acquisition Circuit Temperature in Accurate Online Junction Temperature Estimation

Online junction temperature estimation via temperature-sensitive electrical parameters promises an accurate and highly dynamic way to calculate device temperature. In typical setups, only the temperature dependency of the device is considered, however, the necessary acquisition circuits also have a distinct temperature behavior that is usually neglected. In this work, the impact of the temperature of the acquisition circuits in the form of the PCB temperature on an online junction temperature estimation is analyzed. Measurements for the temperature sensitivity in a climate chamber and a standard calibration of the on-state voltage as a temperature-sensitive electrical parameter are combined to improve the accuracy. The proposed method shows an influence of the PCB temperature on the temperature estimation and enables an improvement of 6.8K in the best case. Furthermore, measurements over ambient temperatures ranging from 0°C to 80°C show a decreasing influence of the PCB temperature on the temperature estimation for higher temperatures. The proposed method is able to compensate for the error induced in the final junction temperature measurement of the device in operation, especially for the lower temperature range, where the on-state voltage has a distinct lower temperature sensitivity.