High-efficiency fault-tolerant three-level SiC active NPC converter for safety-critical renewable energy applications

Fault tolerance plays a critical role for power electronic systems in safety-critical applications such as the distributed generation of renewable energy. Particularly, multi-level power converters have been intensively utilized in medium-voltage or high-voltage distributed generations, the circuit topologies of which contain many more switching devices, leading to increased device failure probability. However, one main drawback with the majority of the existing fault-tolerant power converter topologies is the degraded efficiency due to the addition of the redundant phase leg or power semiconductor modules. A new 3-phase 4-leg fault-tolerant active neutral point clamped (ANPC) converter is proposed to tolerate switching faults under faulty condition, which also provides high efficiency under normal healthy condition by leveraging the redundant leg for current sharing with other main phase legs. In this paper, the efficiency of this fault-tolerant ANPC inverter will be investigated under the proposed switching schemes with the current sharing capability. The experimental results verify that this new 3-phase 4-leg fault-tolerant ANPC converter achieves higher efficiency under the current sharing switching scheme than that without current sharing, under normal/healthy operating condition.