3-레벨 ANPC 인버터의 안정적인 고장 허용 운전을 위한 중성점 전압 균형 제어 기법

Abstract

This paper proposes a simple fault-tolerant control and neutral point voltage balancing control for the stable operation of an active neutral point clamped (ANPC) multi-level-inverter through fault-tolerant switching combination in the case of switch faults. The proposed scheme provides stable fault-tolerant operation through switching combination without using additional switches or devices in a multi-level structure. In addition, it is possible to control the neutral point voltage balance during fault-tolerant operation. If the switch is faulted, fault-tolerant operation is possible by connecting the fault phase to the neutral point. Complex operation is not required compared to other methods and it is simple to implement. However, the conventional method can not control the neutral point voltage balance due to the limited switching state during fault-tolerant operation. With the proposed method, fault-tolerant operation due to switch failure can be implemented easily and the problem of neutral voltage unbalance during fault-tolerant operation can be solved. Neutral voltage balance control can be performed by using different control methods by dividing controllable and non-controllable sectors in the space voltage vector during fault tolerance operation. Therefore, the reliability and robustness of multi-level inverters are improved by the proposed scheme. The validity of the proposed neutral voltage balance control technique was verified through simulation and HIL experiments.