Modeling and Analysis of Winding Open Circuit Fault in Asymmetrical Multi-phase Permanent Magnet Synchronous Machine

The open circuit fault of the phase winding causes the performance degradation, torque ripple and unbalanced magnetic pull of the multi-phase electric machines. In view of the fact that the research on sub-domain model of asymmetric electric machines under the condition of multi-phase open circuit faults has been seldom studied, this paper studies the influence of single-phase and multi-phase open circuit faults on the magnetic field distribution and electromagnetic characteristics of asymmetric six-phase permanent magnet synchronous machine by using a sub-domain model. Generic magnetic field, torque output and unbalanced magnetic pull sub-domain models of the electric machine under open circuit fault modes are obtained. The analytical model is validated with finite element numerical results. Furthermore, the influences of different open circuit fault types on electromagnetic torque, unbalanced magnetic pull, loss and efficiency of the electric machine are compared and analyzed. The result shows that the air gap flux density in the armature reaction field decreases following an open-circuit fault, consequently reducing the output performance of the PMSMs, including torque output, UMP and efficiency. The study could be useful for the performance evaluation and accurate detection of the winding open circuit faults for asymmetrical multi-phase electric machine.