A new structure for multilevel inverters with fault-tolerant capability against open circuit faults

Abstract

In many sensitive industrial applications, reliability of multilevel inverters is one of the main concerns. In conventional multilevel inverters, abnormal conditions occur when a fault takes place in one of the switches. This causes serious damages to other equipment. Under these circumstances, the faulty inverter should be eliminated. In this paper, an efficient topology with fault-tolerant capability is presented. In the proposed structure, if an open-circuit fault takes place in one of the switches, the proposed topology clears the fault based on the proposed switching strategy. Moreover, for decreasing total harmonic distortion (THD), the extended form of the proposed structure is presented. Accordingly, by increasing the output voltage levels, the fault-tolerant strategy is valid and a successful fault clearance is adopted on the switches. The operation of the proposed multilevel inverter and the proposed fault-tolerant strategy are verified through adequate experimental and simulation results performed on a 7-level prototype. The fundamental frequency-switching method is applied to the proposed topology to trigger the power switches for controlling the voltage levels generated on the output. Verification of the analytical results is performed using MATLAB/SIMULINK software.