A New Fault Tolerant Single Phase 5-Level Inverter Topology With Capacitor Voltage Balancing For Solid State Transformer

The research in semiconductor technology and power electronics gives scope to replace a conventional low frequency transformer by power electronic converter based transformer which is known as solid state transformer (SST). Reliability issue is one of the major drawbacks of SST because as it contains power electronic switching devices, the chances of occurring open and short circuit faults are more. Therefore, it requires suitable fault tolerant operation. The basic SST topology consists of AC-DC-DC-AC conversion stages. This paper presents fault tolerant operation of third stage of SST (DC-AC converter) for open circuit faults. In this paper, a novel topology of fault tolerant multilevel inverter (FTMLI) is proposed, which can sustain single switch and some specified multi switch faults. The component count also taken into consideration here and the balancing of capacitors also properly maintained. The proposed topology is giving better results in terms of efficiency, cost and THD under fault tolerant operation. The proposed circuit topology is simulated using MATLAB/SIMULINK tool.