Fault-Tolerant Structure for Cascaded H-bridge Multilevel Inverter using Relays

Abstract

Cascaded H-bridge multilevel inverter (CHBMLI) is the most popular topology for high power industrial applications. There are total 4m number of power electronic switches in a CHBMLI having m numbers of modules (m$\gt 1)$. Because of higher number of switches; the possibility of faults in switches is more. A fault-tolerant structure is proposed for CHBMLI having 3 modules. If any 1 out of 3 modules gets faulty; the remaining 2 healthy modules will continue delivering output voltage with the same amplitude and the same voltage level as in case of normal operation having all the 3 modules are healthy. In this way, the proposed fault-tolerant structure of CHBMLI improves the system reliability by preventing the breakdown of the whole system even if 1 out of 3 modules gets faulty.