Cascaded H-Bridge Multilevel Inverter Operating Under Faulty H-Cell Condition

Abstract

Reliability is an important aspect in the multilevel inverters (MLIs) as they are used for high-power applications and also the number of switch increases with the increase in levels. The efficiency improvement, optimized control strategies, new applications, and fault-tolerant operation are another area of interest of researcher for MLIs. In this paper, the control scheme of cascaded H-bridge multilevel inverter operating under faulty H-cell condition is presented. A modified level-shifted pulse width modulation (LS-PWM) method is used for the control of cascaded H-bridge multilevel inverter operating under faulty conditions. To study the open-circuit and short-circuit fault cases of the H-cell of cascaded H-bridge inverter, two methods of switching have been presented and simulated using MATLAB/Simulink. Neutral shift method is used for achieving balanced line-to-line voltage and line-to-line current. Additionally, to distribute power among H-bridge power cells, rotation scheme in LS-PWM has also been simulated. The simulation results validate the fault-tolerant operation of cascaded H-bridge MLI.