A Novel Low-Cost Endplate Using Same Rotor Core Silicon Steel Sheet for Interior Permanent Magnet Motors in Domestic Applications

This paper proposes a low-cost rotor endplate of interior permanent magnet motors (IPM) for domestic applications. The novelty of the proposed solution lies in utilizing the same rotor core silicon steel sheet as the endplate, so as to eliminate the cost of dedicated rotor endplates. However, since the proposed endplates and rotor core are the same, the magnets can move axially without the limitation of the endplates when their magnet slots coincide. To prevent axial displacement of the magnets, the proposed endplates are rotated axially at a certain mechanical angle concerning the rotor core. In such a solution, the endplates cannot be mounted to the rotor core using rivets since the original rivet holes between them no longer coincide. To solve this problem, additional rivet holes are designed so that some rivet holes between them can coincide after the rotation of the proposed endplates. Besides, due to the high permeability of the endplate, flux barriers in the rotor endplates are studied to mitigate flux leakage at the rotor end. Specifically, the design considerations of the proposed rotor endplate are investigated, including the rotation angle, rivet holes, and flux barriers. Two IPM motors adopting the proposed low-cost endplates at different rotation angles are developed and compared with the conventional IPM motor by using finite element analysis. It shows that the overall performance (back-EMF, cogging torque, efficiency, and complexity of rotor structure) of the IPM motors adopting the low-cost endplates at a proper rotation angle is comparable to the conventional design.