A novel fault tolerant 21-level inverter configuration for PV applications

Abstract

Multilevel inverters are gaining more attention in PV applications due to their advantages like better harmonic profile, low dv/dt and so on. But if any one switch of conventional multilevel inverters (NPC or flying capacitor) fails, the entire configuration has to be shut down. In this regard, a multi-level inverter configuration is proposed in this paper which can be operated during the failure of any power electronic switching device/isolated dc source. The proposed configuration is developed by using four isolated DC sources, nine two-quadrant switches and three four-quadrant switches. Requirement of number of switching devices is considerably reduced compared to conventional multilevel inverters. Detailed analysis is carried out to operate the proposed inverter configuration during the failure of different switching devices/isolated dc sources. The proposed configuration is simulated using MATLAB/Simulink and results are presented for different fault conditions. This configuration can be extended to get more number of voltage levels by cascading proposed inverter units.