Stator Core Loss Analysis and Suppression of Permanent Magnet Vernier Machines

Permanent magnet vernier machine is a new type of permanent magnet machine, which is operated based on flux modulation effect. In this article, the stator core loss of the permanent magnet vernier machine is investigated based on the relationship of the stator core loss to harmonic components of the airgap magnetic flux density crossing airgap and leakage flux not crossing airgap. In this manner, the stator core loss can be analyzed with consideration of flux modulation effect and flux modulation pole structure. First, stator core losses generated by magnetic fields of permanent magnet and armature winding are analyzed. Then, stator tooth fluxes coming from airgap magnetic flux and leakage flux are derived. Also, nonworking stator tooth flux contributing stator core loss but not contributing torque is identified. Based on this, two approaches to suppress the stator core loss of the permanent magnet vernier machine are proposed. Finally, the effectiveness of the stator core loss analysis and suppression is verified by finite-element analysis and experiments.