Fault diagnosis of T-type three-level inverter based on bridge voltages

Abstract

Multilevel inverters have been widely used in various occasions due to their advantages such as low harmonic content of the output waveform. However, because multilevel inverters use a large number of devices, the possibility of circuit failure is also higher than that of traditional inverters. A T-type three-level inverter is taken as the research object, and a diagnostic study is performed on the open-circuit fault of insulated gate bipolar transistor (IGBT) devices in the inverter. Firstly, the change of the current path in the inverter when an open-circuit fault of the device occurred, and the effect on the circuit switching states and the bridge voltages were analyzed. Then comprehensively considered the bridge voltages, and proposed a fault diagnosis method for a T-type three-level inverter based on specific fault diagnosis signals. Finally, the simulation verification was performed. The simulation results prove that the proposed method can accurately locate the open-circuit fault of the inverter device, and has the advantage of being easy to implement.