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Abstract

In traditional electric motors, contact-type mechanical bearings entail various complications. For example, lubrication may contaminate commercial products and friction loss limits system efficiency at high speeds. Bearingless motors— a special class of electric motors where bearing function is realized by the stator via magnetic levitation—can resolve the issues of contact type mechanical bearings. This project presents the design of a new interior permanent magnet bearingless slice motor that facilitates flux-weakening control for high-speed operation. The prototype motor consists of a dipole IPM slice rotor with ferrite magnets, a 12-tooth stator core, 12 concentrated coils grouped into quadruple 3-phase windings, and four 3-phase inverters. This thesis discusses the design process for the prototype, including parametric studies aimed at reducing high air-gap and coil flux harmonics, minimizing cogging torque, and creating a suitable design for flux-weakening. The thesis presents preliminary test results on flux-weakening operation, which show the potential to achieve a speed limit that is constrained only by rotor material strength.