Design of a multi-layer interior-ferrite permanent-magnet synchronous machine for traction applications

A novel design of an interior ferrite permanent magnet (PM) synchronous machine with a multi-layer configuration is proposed for traction applications. Although the ferrite magnet can be disadvantaged by its low residual flux density and energy product, it is proposed that flux-focusing and multi-layer configurations can be utilized to harness both the PM torque and the reluctance torque to recoup the loss of the PM torque due to its intrinsic property. Machines with up to three-layer magnets are presented and evaluated comprehensively. The results suggest that the two-layer machine provides the best performance among the three configurations. Furthermore, compared with a commercial rare-earth equivalent, the proposed ferrite machine is shown to have nearly the same torque with 32% less electromagnetic losses. The findings underpin the interior ferrite PM synchronous machine as an attractive alternative for traction applications.