Research On The Alternating Current Loss Of High-temperature Superconducting Tape And Structures

High-temperature superconducting(HTS)tape has high current density,low loss and excellent mechanical properties,which is widely used in the fields of electric power,new energy,medical treatment and high-field magnets.Superconducting materials will experience alternating electromagnetic field in the practical engineering application,which will generate significant alternating current(AC)loss.The AC loss will cause the temperature rise of superconducting materials,and directly affect the stability of superconducting devices in low-temperature environment.Therefore,it is meaningful to study the AC loss of superconducting structures in their large-scale application.The accurate estimation of AC loss can effectively reduce the refrigeration cost of superconducting equipment.In this paper,the AC loss is numerically estimated in superconducting tape and structures.The main contents are as follows:Firstly,the basic properties and development process of superconducting materials are introduced,and the application of superconducting technology and the research status of AC loss are analyzed.The basic theory of superconductor,the generation mechanism of AC loss,simulation method and experimental measurement method are also introduced.Secondly,the AC loss of HTS coil is numerically simulated and preliminarily tested.The model is verified by comparing the simulation results with theoretical and experimental results.The electromagnetic characteristics of pancake coils with nonuniform critical current are numerically simulated.Considering the non-uniform distribution of critical current density along the length and width direction,the simulation results of AC loss are given in the coil.Then,the effect of the coil's structure on the electromagnetic characteristics of the pancake coil is discussed.When the number of turns,inner radius and stacking layers of coil are changed,the varying trends of magnetic field and AC loss are also analyzed.It provided a theoretical basis for the structural design of coil.Finally,the effects of tension and torsion loads on the electromagnetic properties of superconducting tape are studied.Numerical results show that the effect of mechanical strain on AC loss depends on the electromagnetic loading mode.When the twist pitch remains the same,the variation trend of AC loss of tape under different transverse tensions is analyzed with the transmission current and alternating magnetic field,respectively.On this basis,the AC loss of tape with non-uniform critical current density is discussed under tensile and torsional loads.The AC loss of the tape divided into many filaments is explored,and the AC loss of cables with different stacking layers is given.