Time-Domain Characterization and Detection of Open-Circuit Faults for the H-Bridge Power Cell

This article presents the time-domain characterization of semiconductor open-circuit switch faults (OCSFs), such as an open switch with a healthy diode and switch-diode pair open for the H-bridge power cell. The inverter fault signatures under diagonally opposite open switch fault conditions with a healthy diode are approximately similar; therefore, this article presents a detection algorithm with a unique identification of each faulty switch within the H-bridge power cell. The proposed algorithm is also designed to detect and identify multiple OCSFs. The nonideal characteristics of semiconductor switches are considered for the identification of switch faults. The well-known unipolar sinusoidal pulsewidth modulation technique is used for the switching of semiconductor devices for the single power cell. The mathematical expressions have also been derived to find out the effect of the switch fault using a double Fourier integral solution and the switching states. The analytical expressions have been developed for the switched output voltage waveforms under ideal switching conditions. The behavior of the switch faults has been analyzed using inverter output voltage, load current, and total harmonic distortion of the pulsewidth-modulated inverter output voltage.