Direct current carrying Type II superconductors present a dc electric field under external perpendicular AC magnetic field, commonly referred to as “dynamic resistance effect”. Two kinds of AC losses occur in this situation: dynamic loss due to the interaction between the DC current and moving fluxons, and magnetization loss due to shielding current caused by the external AC magnetic fields. In general, HTS coated conductors have one substrate layer, which can be non-magnetic (Hastelloy) or magnetic (NiW). In this paper, we present the impacts of the magnetic substrate and their strength of ferromagnetism on dynamic loss and magnetization loss by using a finite-element method model based on H -formulation. This work reveals that the magnetic substrate layer does influence the dynamic loss and magnetization loss of HTS coated conductors. The dynamic loss is reduced by the adjacent magnetic substrate in the low field region and is increase in the high field region. The magnetization loss is reduced significantly by the magnetic substrate. This work will help choose HTS coated conductors with different substrate layers in different applications.

The main obstacle for the application of the high-temperature superconducting (HTS) coated conductors (CCs) in AC energy applications is the relatively large AC loss. To tackle this, several forms of HTS cables for AC applications have been invented and investigated, such as the HTS Roebel cable, Cable on Round Conductor (CORC), and Twisted Stacked Tape Cable (TSTC). In this paper, the possibility of encapsulating Roebel cables into a single HTS CC is investigated, from which a novel conception of a Roebel tape is proposed. Compared with the existing HTS cables, HTS Roebel tapes are more compact, more capable at carrying large current with minimised AC losses, and easier to manufacture. A 3D finite element method (FEM) model of the Roebel tape is built to optimise the structure and verify the performance. The results show that, compared with normal ReBCO CCs, Roebel tapes with optimum patterns can reduce AC transport losses by 60% through field-cancelling and can reduce magnetisation losses by the factor of the filament number through patterning. With excellent loss reduction performance and high current capability, the Roebel tape shows great potential to become a revolutionary HTS cable for high-current power transmission and AC machine applications.

When a superconductor is exposed to an AC magnetic field whilst carrying a constant DC transport current, a DC electrical resistance can be observed, commonly referred to as “dynamic resistance”. This dissipative effect can play a critical role in many potential high-temperature superconducting (HTS) applications, especially for the AC-field-actuated HTS switch, which is the key component in the HTS transformer-rectifier flux pump (TRFP). The characteristics of the HTS switch determine the performance and reliability of TRFP. In this paper, we report a numerical study of a new HTS switch design made of series-connected YBCO stacks. This study aims to obtain insights into the characteristics of dynamic resistance and power loss, including their relationships with the amplitude and the frequency of the AC magnetic field. The energy conversion efficiency of the HTS switch is also investigated. This work will help design a high-performance AC-field-actuated HTS switch.

When a type-II high Tc superconductor carrying a direct current is subjected to a perpendicular AC magnetic field, a direct current voltage will appear. This phenomenon is called dynamic resistance effect. In general, the high temperature superconducting (HTS) coated conductor (CC) has two stabilizer layers. However, the impacts of two stabilizer layers on the dynamic resistance, DC electrical field, losses, and temperature rise haven't been studied yet. This paper presents the impacts of the stabilizer layers and their resistivity on the dynamic resistance effect and HTS CC tape's thermal-electromagnetic behaviors by using a temperature dependent FEM model. This work reveals that the stabilizer impacts significantly on the dynamic resistance, dc voltage, power loss, and temperature rise. It is will help design high-performance AC magnetic field-controlled PCS and switches based HTS devices.

Conductor on round core (CORC) cables wound by high-temperature superconducting (HTS) tapes have received much attention due to the advantages in power capacity and mechanical flexibility. This paper first developed a 3D model for a CORC cable through the finite-element method (FEM). Next, the total AC loss caused by transported current only was investigated, revealing the eddy current loss in the tube former contributes to the cable loss. The numerical CORC model was validated by published measurements. Moreover, the AC loss that resulted from a simultaneous presence of transport current and magnetic field was explored. With the induced current, the magnetisation loss generated in superconductors can increase the total loss. It is concluded that the addition of a magnetic field can result in a surge in the total loss of a current-carrying cable.

Superconducting Conductor on Round Core (CORC) cables fab-ricated from high temperature superconducting (HTS) tapes are capable of carrying enormous electrical current density, to be widely used in a variety of superconducting applications such as power transmission, fusion, and magnetic resonance imaging (MRI) [1]. However, the AC losses induced in the superconduct-ing tapes under alternating current or magnetic field generate heat dissipation which can decrease the overall electric power ef-ficiency [2]. Therefore, it is essential to analyze the AC loss be-havior of CORC cables as well as consider methods to reduce it. This paper presents an AC loss study of CORC cables with sev-eral different superconducting layer thicknesses. The CORC ca-ble simulation model is built in a commercial software named COMSOL Multiphysics based on the finite-element method (FEM) solved by the three-dimensional (3-D) H-formulation. By implementing FEM simulations, the cases of increasing the de-gree of freedom of superconducting layers have been considered, and the AC losses of a single layer CORC cable with three tapes mounted around the core have been calculated and analyzed for different layer thicknesses. Simulation results are verified with experimental results measured in previous literature.