A Low Coupling Fault Tolerant PMA-SynRM With Mixed-Pitch Segregated Windings

Mutual coupling effect between different winding modules causes undesirable effects for the fault tolerant machine drives, such as current distortion, torque ripple, and increased fault current. In this article, a mixed-pitch segregated winding configuration is presented for a triple modular fault tolerant permanent magnet (PM)-assisted synchronous reluctance machine (PMA-SynRM). It exhibits less mutual coupling effect between the different winding sets, which leads to improved fault tolerance compared to the existing full-pitched segregated windings. The mutual coupling effect is described by deriving the magnetomotive force (MMF) profile, and the fault tolerant performance improvement is proven by detailed finite-element (FE) analysis and prototyping tests in healthy and various fault conditions. The results confirm that the presented winding machine has the same healthy performance as the conventional full-pitched windings, and it operates in a more balanced manner with less current distortion and lower turn fault current. It will become a more competing candidate for the safety critical applications.