Reliable detection of open-circuit faults in cascaded H-bridge multilevel inverter via current residual analysis

Fault diagnosis in Cascaded H-bridge (CHB) inverter-fed drives is an important task that increases the reliability and safety of such systems. The need for fault diagnostics is particularly acute on account of the large number of power semiconductor devices, which increases the probability of device faults, including open-switch faults. However, due to the wide variety of faults that may occur it may be difficult to detect particular faults using conventional techniques. Therefore, fault classification is required for the identification of the possible fault types. A simple classification method is proposed in this paper to identify the type of fault based on the current waveform. The proposed method does not require additional current sensors but relies greatly on pre-defined threshold limits. Simulation results are presented to verify the effectiveness of the proposed method.