Open loop real-time power electronic device junction temperature estimation

Temperature management and control are among the most critical functions in power electronic devices, as operating temperature and thermal cycling can affect device performance and reliability. Therefore, it is useful to develop a device thermal model, which can be implemented in real-time and used to estimate temperature variations within the active region of the device. This paper begins by presenting a device thermal model suitable for a MOSFET power-switch derived from the seven-layer physical structure of the device. However it is shown subsequently that a third-order thermal model can give satisfactory estimates of device temperature. Furthermore, computational efficiency can he improved if the model is implemented as a third-order difference equation. Modelling results are compared with real-time temperature device measurements.