A Real-time Physics Based Digital Twin for Online MOSFET Condition Monitoring in PV Converter Applications

Abstract

This article proposes a fast, lightweight and physics-based digital twin to estimate the real-time junction, case and heat sink temperatures of the switching device in a photovoltaic (PV) boost converter. A lookup table approach is used to model the electric behavior while a traditional Cauer approach is used for the thermal model. To extract the thermal resistances of the MOSFET layers and convection, a finite element method (FEM) simulation is performed. To validate the digital twin, a physical replica of the boost converter is built and a real mission profile is applied. The resulting heat sink temperature profile has a mean average error of 0.8 degrees C with an increase in error at higher temperatures. In future work this twin will be used to separate the effect of temperature and degradation on the on resistance of the MOSFET to monitor degradation during operation.