Multiple Open-switch Faults Detection and Fautls Tolerant Method of three-level three-phase NPC Active Rectifier

This paper presents multiple open-switch faults detection and faults tolerant methods for the 3-level 3-phase neutral point clamped (NPC) active rectifier. The 3-level 3-phase NPC active rectifier is comprised of many switching elements, which is increased the probability of open-switch faults compared to conventional 3-phase AC/DC PWM converter. These open-switch faults generate the imbalance of the input AC currents and output DC-link voltage pulsation. As a result, system performance and efficiency are reduced. Therefore, accurate and quick fault detection is required. Further fault tolerant is needed. In this paper suggests the multiple open-switch faults detection method and fault tolerant without additional component. The proposed faults detection method is getting by combination of grid angle and output DC-link voltage ripple component. The fault tolerant is implemented by changing voltage reference. The usefulness of the proposed methods is verified through the simulation results.