Quench Precaution Research On Excitation Windings Of Double Stator High-Temperature Superconducting Machine

With the rapid development of direct-drive wind power generation technology,high temperature superconducting machine(HTSM)has attracted more and more attention because of its advantages such as small volume and weight,compact structure,high power density and efficiency.In recent years,in order to improve the reliability of high-temperature superconducting machines,scholars at home and abroad began to study the stator-excited high-temperature superconducting machines with static seal and furthered the research on its preventive measures.In this study,double-stator high-temperature superconducting machines(DS-HTSM),which are static sealed,are analyzed.Combined with the current research of damping shielding systems,the working principle and configuration optimization of damping shielding system for static-sealed DS-HTSM are studied in detail.The main research contents of this paper are as follows:1.Based on the separation of armature windings and excitation windings of DS-HTSM,the working principle of this type of field-modulation superconducting machines is illustrated,and the mapping pattern between the harmonic magnetic field orders in the dual air-gaps and rotor pole pairs is revealed.2.Based on the DS-HTSM permeance function,inner air-gap flux density expressions are derived,which have crucial impact on the critical current of HTS excitation windings.Analytical method is adopted to analyze the influence of the magnetic field,which is induced by the damping windings and copper shield layer in the damping system respectively,on the amarture field and the excitation field.Also the finite element analysis(FEA)is applied to validate the analytical method.3.2-dimension FEA model is eastablished and optimized with respect to the damping shielding system location and the damping conductor quantity and material to get the optimal design scheme of the electromagnetic shielding system of DS-HTSM.Meanwhile,the short-circuit characteristics of DS-HTSM under the condition of three-phase symmetric and asymmetric short circuits are studied to verify the effectiveness of the designed damping shielding system.4.A DS-HTSM prototype is manufactured and the experimental test platform is set up to test the no-load back electromagnetic force(EMF)and output power of the machine.Experimental results show that the designed damping shielding system is feasible to prevent the loss of excitation windings of DS-HTSM.