Fault Tolerant Control of Five-Level Inverter Based on Redundancy Space Vector Optimization and Topology Reconfigruation

Abstract

Compared with two-level and three-level inverters, five-level inverters have more redundant space vectors to implement flexible control strategy. A fault tolerance method for open circuit fault of power tube in Neutral Point Clamped (NPC) five level inverter is proposed. The open circuit fault of inverter is divided into type I and type II in this paper. Redundant space vector optimization and topological reconfiguration fault tolerance strategies are used for type I and type II failures, respectively. The basic vector of the synthetic reference vector $\text{U}_{\mathrm {ref}}$ is reoptimize according to the redundant vector, and get a new control strategy after the decision. This method enables the inverter to achieve fault-tolerant operation without modifying hardware or adding bridge arms. The output performance of the inverter after fault is guaranteed and the cost of fault tolerance is greatly reduced. The feasibility and effectiveness of the proposed fault-tolerant method are verified through experiments.