Research On Features And Design Method Of The Superconducting Armature Windings

Superconducting materials have many excellent features such as fairly high current capacity and low loss.The combination of superconducting technology and electrical engineering especially the field of large scale wind power generations is highlighted because the power density and efficiency can be improved by utilizing superconductors.Theoretically,superconductors have the potential to launch the energy revolution.Therefore,it is of great significance for the related research and technical reserve of superconductivity and superconducting motors.On the basis of the characteristics of both superconductors and electric machines,the computing methods and design features of power generators with superconducting armatures are investigated by considering their power density and efficiency.The main research contents and contributions are as follows:(1)On the basis of the theory and characteristics of superconductors,the AC loss is deeply studied.According to the structural parameters of coated superconducting conductors,the proposed FEM model is modified,which can improve the computing speed and accuracy effectively.According to the structural features of multifilament superconductors,a fast AC loss calculation method of superconductor coils is proposed,which is verified by experimental data.All these findings above can be used in the calculation of AC losses during the design process of superconducting machines.(2)An armature experiment platform based on field excitation device is build,and the current capacity of the superconducting armature winding is tested.The field exciter is designed and manufactured to simulate the slot flux leakage generated by the actual motor.The electromagnetic design of the armature winding can be verified by measuring the critical current of the armature under the simulated magnetic field.(3)Considering the difficulty in designing and manufacturing the rotating cryogenic system of the superconducting windings,the structure of permanent magnet(PM)synchronous motor with superconducting stator armature is discussed,of which the design features are summarized.The phase current and power density of the proposed PM machine can be improved obviously by utilizing superconducting coils because of their high current capacity and low loss.Then the influence factors of the extreme output power are analyzed,and a new tapering stator tooth structure is proposed to break through the limitation of severe saturation of ferromagnetic materials.In terms of output efficiency,the installation position of the superconducting armatures is analyzed in order to reduce the AC loss and make full use of the advantages of superconducting materials.(4)The electromagnetic design of a 10MW permanent magnet wind power generator with superconducting armature windings is proposed.In terms of the demagnetization of the rotor poles,a new shape of the PM bulk is proposed.The output power can be improved obviously while the efficiency is nearly unchanged,which verifies the design and analysis methods of superconducting armature windings proposed in this thesis.The strong adaptability of superconducting technology in large scale direct drive wind power generators is revealed.