Effect of fault in output capacitor due to its parasitic resistance in modular DC-DC three-level converter

In this paper, the behavior of a two-module converter after capacitor fault is investigated in this paper. Three-level boost converter in a modular fashion offers multi-input energy sources. This converter with a nonlinear control can control the input power and balance the voltages across the output capacitor. Since aluminum electrolytic capacitors, which have a low lifetime, are usually used in such converters, this paper investigates fault on the output capacitor. The fault is modeled as a parallel resistance, which is high when the capacitor is healthy but low when the capacitor fault. To study the system waveforms, two cases are considered. A high value to show the normal mode and a small value to show the fault mode for the fault resistance are set. MATLAB/Simulink software is used to perform the modeling and validate the hypothesis. The voltage balance and the regulation of the DC bus voltage are studied for these two scenarios.