A Simple and Efficient Strategy for Online Detection of Multiple Open-Switch Fault in Multiphase Machine Drive Systems

As the fault localization for multiphase machines is critical for fault isolation and active fault-tolerant strategies, reliable fault diagnosis strategy is essential to be proposed. After open-circuit fault occurs, harmonic current vectors will follow different trajectories according to different faulty phases. However, this event can only be evident in case of single phase fault occurrence. Thus, existing technique can only identify limited types of open-switch fault. This article proposes a simple and efficient open-switch fault detection strategy to extract fault features. Proposed strategy is able to locate any combinations of open-switch faults, which cannot be realized in the previous literature. The faulty phases are detected first to reduce computational burden and for avoidance of false alarms. Then the faulty switches are determined on the basis of the direction of current vectors in the harmonic plane. Taking account of open-switch faults in different phases, normal current vectors are reconstructed with newly defined auxiliary current variables, which can be utilized to detect the failure of multiple switches and result in enhanced robustness. Experimental results validate the effectiveness of the proposed multiple open-switch fault detection method in a seven-phase machine at 5.5 kW power level.