Fault tolerant methods to reconfigure Multilevel level inverter for single and multiple open circuit switch faults

Abstract

Device ratings limitations of two-level inverters restricted their applications and increased the demand for Multilevel inverters (MLI) for various high-power medium-voltage applications. However, it is not just the low device ratings that have enhanced the impact of MLI, but there are other key factors such as less good harmonic profile (filter size) and fault tolerance. Fault tolerance of MLI sustaining the various internal and external faults contributes to inverter reliability and plays a vital role to enhancing practical feasibility. However, achieving fault tolerant operation of MLI by control its switching operation rather than involving any external/auxiliary hardware is the most economical solution. Thus, considering the most popular modular redundant classical MLI i.e., Cascaded H-Bridge, this paper presents the simplest fault tolerant strategies practically used to reconfigure CHB from open circuit (oc) switch fault(s). The fault tolerant operation (FTO) is demonstrated considering three-phase eleven-level CHB in MATLAB/Simulink environment.