Fault-Tolerant PV Multistring Inverter

In photovoltaic (PV) systems, the reliability of the power converter is of main importance in order to have cost-effective solutions. Designing power converters with fault-tolerant capability is a solution to improve the reliability of the system, guaranteeing service continuity in case of failure of elements of the converter, in particular the semiconductor devices. In this paper, a fault-tolerant two-stage PV multistring inverter is proposed. The proposed fault-tolerant design includes a single redundant switching leg with ancillary circuitry, which is used to reconfigure the structure and continue operation in case of a switch failure. Unless existing fault-tolerant solutions which focus either on DC-AC or DC-DC converter stages, the proposed fault-tolerant PV multistring inverter can handle a fault on any switch of the two conversion stages. The switch fault diagnosis on the DC-AC stage is performed with an existing solution, while a novel method is proposed for the switch-fault detection on the DC-DC stage. Simulations are provided to verify the feasibility of the proposed fault-tolerant solution.