Analytical Solution of Magnetic Field in High-Speed Permanent Magnet Synchronous Machines With Novel Composite Rotor

This article presents novel composite magnetic materials (NCMMs) to solve the key issue of high rotor temperature rise and stress concentration in high-speed permanent magnet synchronous machines (HSPMSMs). Utilize low conductivity and circumferential continuity of NCMMs, the topologies of HSPMSM with novel composite rotor (NCR-HSPMSM) are proposed. The NCR-HSPMSM contains two topologies. The first topology adopts the single excitation structure, and the excitation source only contains NCMMs. The second topology adopts the hybrid excitation structure, and the excitation source contains sintered permanent magnets and NCMMs. On the basis of conformal mapping, the general analytical solution of the open-circuit magnetic field in NCR-HSPMSM is obtained. In NCR-HSPMSM, the subdomain model is used to anticipate the armature reaction field. Also, calculable are the back electromotive force (EMF), cogging torque, and electromagnetic torque. The developed model is used to guide the machine design and save optimization time. A good agreement between predicted and finite-element calculation is achieved. Compared with the conventional HSPMSM, the rotor eddy current loss and rotor strength are analyzed, and the electromagnetic performance is analyzed with different composition parameters of NCMMs by the developed model. And the materials properties are measured by experiment.