Modeling MOSFETs for fault-managed power systems: a transient analysis based on capacitance dynamics

The nonlinear, dynamic change in junction capacitance of MOSFETs during switching is crucial in modeling and analyzing the transients in Switched-Mode Power Supplies. In this paper, these dynamics are addressed and an improved MOSFET model is developed for applications in fault-managed power systems. The momentary change in MOSFET parasitics is modeled based on generic equations to analyze the switching performance in different load conditions. The developed model has shown a certain degree of accuracy required to define safe operating conditions for precise fault detection in fault-managed power systems. The change in gate capacitance is shown and used in updating the MOSFET model. The proposed model is simulated in Simscape and the accuracy of the model is validated using experimental data from test circuits with various load combinations.