Open Circuit Fault Detection and Switch Identification for LS-PWM H-Bridge Inverter

The increases in number of power semiconductor devices in multilevel inverters increase the probability of fault occurrence and resulting the reduction in the system reliability. The semiconductor switch faults reduce the production quality and with increased duration of fault occurrence may also be the reason for complete system damage. In H-bridge inverters, the fault signatures of diagonally opposite switch fault conditions are approximately similar. Therefore, a fast fault detection with accurate switch identification technique is required. This brief presents a novel fast fault detection with accurate switch identification technique for an H-bridge inverter. The open switch fault with healthy diode is considered for the analysis. The non-ideal characteristics of semiconductor switches are used to identify open switch fault. This brief also proposed a switching time-domain open circuit fault detection technique. The pulse-width modulated inverter (PWMI) output voltage and load current have been used for detection and identification of the switch faults. The level-shifted pulse width modulation (LS-PWM) technique is used for three-level inverter voltage output.