Investigation of a fault-tolerant three-level T-type inverter system

This paper proposes a fault-tolerant three-level T-type topology and fault-tolerant control strategy for inverter system. The fault isolating circuit, a fault-tolerant bridge and a redundant fourth-leg are added to the original T-type topology, providing the inverter with fault-tolerant capability. A fault isolating circuit is used to isolate the faulty leg quickly, eliminating its influence to other parts. A fault-tolerant bridge is used to connect the redundant fourth-leg to the output of the faulty main-leg. Additionally, the redundant fourth-leg can not only substitute the faulty main-leg caused by switch open circuit or switch short circuit fault, but also balance the neutral-point voltage in the case of switch fault. Consequently, the fault ride-through performance of power switches has been improved. A fault-tolerant three-level four-leg T-type inverter system is modeled in MATLAB/Simulink. Simulation results verify the feasibility and reliability of the proposed fault-tolerant inverter system.