This paper presents a detection method for an open-switch fault in cascaded H-bridge multilevel inverters. Recently, cascaded H-bridge multilevel inverters (CHMIs) are widely used in high power systems. Therefore, the reliability of this topology has become an important factor. To improve the reliability, detecting methods for an open-switch fault are required. The proposed method is based on the current path analysis according to zero-voltage switching states. The location of both faulty cells switches can be detected by the current waveform and zero-voltage switching states. This method is applicable when using the level-shifted PWM that is commonly used for a modulation method in CHMIs. The performance of proposed detecting method is verified by simulation and experimental results.
