Experimental And Numerical Study On AC Losses Of Multi-wire HTS Conductors With Ferromagnetic Substrate

Superconducting electrical application has shown its wide prospectwith the development of high temperature superconducting (HTS) materialand its research. AC loss of HTS wire is the key factor of superconductingapparatus’stability and economical efficiency. It is closely related with thedesign of superconducting apparatus. Thus, it is important to analyses theAC loss characteristics of multi-wire HTS conductors. On the other side,ferromagnetic material substrates are common in2nd generation HTS wires.The AC losses of HTS wires will be affected by the ferromagnetic substratebecause of its permeability. This raises the significance of the study of theAC losses of HTS wires with ferromagnetic substrates. In this dissertation,following works are accomplished:(1) A numerical model for HTS wires with ferromagnetic substrates isbuilt. The model is based on H formulation and E-J power law with finiteelement method. In order to calculate the loss in substrate layer, the relativepermeability and power characteristic of ferromagnetic material isconsidered.(2) An AC loss measurement system is set up based on electricalmethod. The validity of the measurement system is confirmed from variousaspect. The loss measurement results’ dependence of compensate voltage’samplitude, voltage lead’s arrangement and current frequency is discussed.(3) AC loss of a double-wire HTS conductor and a triple-wire conductor with horizontal arrangement is measured and calculated. Currentdirection and wire arrangement’s influence on AC loss is taken intoconsideration and analysed with the help of magnetic strength and lossdensity distribution schematics ploted by simulation software.(4) A simplified cable model is fabricated by ten HTS wires withferromagnetic substrates. The AC loss of the cable model is measured. Themeasurement result is compared with the self-field loss.The results of experiments and calculation indicate that the numericalmodel and the measurement system in this dissertation is valid. The currentdirectionand wire’sarrangementwillaffecttheAClossesofthe multi-wireHTS conductor when wires are horizontal arranged. AC losses of a HTSconductor with cylinder arrangement is smaller than the self-field loss.The conclusion of this dissertation will support the design ofsuperconducting electrical equipment.