A fault-tolerant reconfiguration system based on pilot switch for grid-connected inverters

Abstract

The multi-level inverter has been widely applied in high-power applications, especially in grid-connected systems. In addition to some of the benefits provided by the multi-level inverter, it has the disadvantage to be more prone to failure because of the large number of components used. Therefore, fault-tolerant control of multi-level inverters is critical to ensure the stability and reliability of the system. This paper introduces a fault-tolerant reconfiguration system (FTRS) based on pilot switch for grid-connected inverters. FTRS includes the grid-connected inverter using pilot switches and a fault-tolerant modulation algorithm. FTRS aims to reduce the damage of insulated gate bipolar transistor (IGBT) failure of cascaded H-bridge (CHB) inverter and meet such application requirements as grid-connected systems. The grid-connected inverter using pilot switches and its modulation algorithm can complete fault isolation without the redundant backup H-bridge and can make H-bridge reconfiguration after the system receives the fault signal so that the healthy H-bridge will keep working with voltage peak. Reliability evaluation and comparison of the FTRS and other inverters are presented. The validation of the proposed method is confirmed by simulation and experiment results on the five-level grid-connecter inverter.