Research on the Improved Fault-Tolerant Control of ANPC Three-Level Converter

In recent years, the reliability requirements of active neutral-point-clamped (ANPC) three-level converter are getting higher and higher with its large-scale application. In order to overcome the problem of the limited fault-tolerant capability of the basic ANPC three-level converter when compound faults occur, an improved fault-tolerant topology based on component sharing was proposed in this paper. Compared with the basic ANPC three-level converter topology, two bidirectional thyristors and a double-pole double-throw switch are added to each phase, which can realize Fault-Tolerant Control (FTC) for multiple fault types and greatly improve the reliability with small additional costs. The corresponding self-diagnosis FTC algorithm composed of topology reconfiguration module, switch state generation module, and PWM output control module is also put forward. With the real-time generation of switch state, the reconfiguration of fault-tolerant topology is easy to realize and adaptable. Finally, the effectiveness and feasibility of the proposed topology and FTC algorithm are verified by simulation and experimental results.