Modular Stator High Temperature Superconducting Flux-Switching Machines

Flux-switching permanent magnet (FSPM) machines have advantages of robust rotor, strong permanent magnet (PM) dissipation ability, etc, but its flux-weakening capability is poor for its constant PM flux linkage. High temperature superconducting (HTS) excitation windings can produce higher flux density than PM excitation and modify the airgap flux density easily. But if the HTS coils are placed adjacent to the armature winding in the same slot, the heat produced by the armature winding is difficult to cool down. In this paper, a modular stator HTS flux-switching (HTS-FS) machine is first proposed, and the operation principle is described in details. Second, mathematical equations are proposed and detailed electromagnetic design has been done. Then, the optimization of width of flux barrier, rotor pole arc and split ratio have been made to get higher back-EMF, higher output torque capability, and lower torque ripple. Moreover, the comparisons of key performance indexes between HTS-FS machine and conventional FSPM machines have been made. The results show that the HTS-FS machine can produce higher back-EMF than FSPM machine, and at small armature current, it can produce higher torque with little electromagnetic saturation.