Electromagnetic design and performance analysis of coreless superconducting machine

With the development of offshore wind power generation, there is an urgent demand for high-power wind turbines. Superconducting machines with high power density and efficiency are one of the solutions for wind turbines of 10 MW and above. This paper summarizes the existing superconducting synchronous generators in several structural forms and features, and considers that the coreless machine can avoid the impact of core oversaturation on the power density increase of the machine, which is the development direction of the superconducting machine. In this paper, the structural topology of a coreless superconducting machine is established and the similarities and differences between its structure and that of a conventional one are analyzed. Since the conventional magnetic circuit method is no longer applicable, a designing model based on the analytical method is established for the designing of coreless machines, which considers the effects of slotless armature, the superconducting excitation winding thickness and the nonlinearity of the ferromagnetic material. Based on this method, the magnetic field distribution is solved and verified with the finite element method. Further, the effect of the superconducting excitation winding opening angle on the magnetic field in the air gap of the machine is investigated, and the machine structure is optimized based on this. The steady-state and transient performance analysis of the machine is carried out to illustrate the operating characteristics of the coreless superconducting machine. The design method and analysis results of this paper can provide a reference for building higher power density coreless superconducting wind turbines.