Quantitative Comparison of Double-Stator Permanent Magnet Vernier Machines With and Without HTS Bulks

This paper quantitatively compares three types of double-stator flux-modulation permanent-magnet (PM) machines, namely the vernier machine, vernier machine with HTS bulks, and magnetic-geared machine. Due to adopting the double-stator topology, these PM machines achieve the higher energy transmission and power conversion than the single-stator counterparts. Also, the design for the proposed machines are to respectively use the flux-modulation pole, HTS bulk and the flux-modulation ring for modulating the low speed rotating field of the PM rotor and the high speed rotating field of the armature windings, hence obtaining the gear effect for low speed operation. It should be noted that by using the HTS bulks can not only efficiently improve the flux modulation effect of the vernier machine, but also greatly reduce the machine flux leakage. By using the finite-element-method, their performances are compared, hence verifying the validity of the machine design.