Performance Improvement of a Five-Phase PMSM Drive Under Open Circuit Stator Faults

Abstract

Five-phase Permanent Magnet Synchronous Motors (PMSM) are the most common types of multi-phase synchronous motors. Five-phase PMSMs have remarkable advantages such as reduced torque pulsation, higher fault tolerance capability and higher reliability compared to the three-phase counterparts. They also offer additional inherent degrees of freedom which can be used for fault-tolerant operation. However, stresses on the PMSMs such as electrical, thermal, and environmental are increasing and therefore lead to the total failure of these motors. The major faults of electrical machines can be classified as bearing, stator windings, demagnetization of the magnets, and eccentricity faults. The tolerable faults of rotating electrical machines which have the highest rate among the total faults are stator-related faults. Since drives of multi-phase machines consist more power switches compared to drives of conventional three-phase machines, the possibility of open-phase faults is higher than other type of faults. Therefore, fault tolerance of open-phase faults becomes more important nowadays. The fault-tolerant controller (FTC) is used to compensate the open-phase faults. An FTC is required to determine the type of fault and intervene immediately to implement appropriate control strategy to ensure the continuous operation. In this study, an FTC system is proposed for a five-phase PMSM under open-phase faults in one and two phases. Under faulty conditions of PMSM, the proposed FTC system improves the average output torque and reduces the ripples in the torque and speed significantly.