An Improved Configuration For Cogging Torque Reduction In Flux-Reversal Permanent Magnet Machines

An improved configuration of flux-reversal permanent magnet (FRPM) machines is proposed by introducing a small air-gap between two adjacent magnets belonging to the same stator tooth to reduce cogging torque. A magneto-motive-force (MMF)-permeance model is employed to derive the analytical expression of cogging torque for FRPM machines, which takes the small air-gap into consideration. According to the analytical model, optimal design of the introduced air-gap is investigated for cogging torque reduction and verified by 2D finite element analysis.