A Fault-Tolerant Single-Phase Inverter Using Redundant Leg

Single-phase inverters are increasingly used in a variety of applications from renewable energy systems to un-interruptible power supply. In the design and operation of these inverters, reliability remains a major concern. The single-phase inverter offers fault tolerance by including a redundant leg. The conventional redundant leg configuration uses four triode for alternating current (TRIAC) and two switches. The voltage seen across TRIACs used to connect the redundant leg is pulse width modulated (PWM). The high dv/dt across the TRIACs in the conventional topology due to PWM causes spurious turn ON across TRIACs. It leads to a short-circuit (SC) across the terminals. Thus, there is a need to modify the conventional TRIAC arrangement that is used to connect the redundant leg. In this paper, an updated TRIAC arrangement for a fault-tolerant single-phase inverter is proposed. The proposed TRIAC arrangement uses a split inductor filter to provide a sinusoidal voltage across the TRIACs. Thus the rearrangement of TRIAC ensures the lower dv/dt across the terminals. The reconfiguration of TRIACs is verified in simulation and experimentally through a 200V single-phase inverter with redundant leg prototype.