Abstract-AC loss is an important factor in designing and running of high temperature superconducting (HTS) devices. Recent years have seen many studies on the measurement of AC loss of HTS coils carrying sine-wave current. However, in fact, many practical HTS devices don’t operate under sine-wave current. For instance, the current waveform of a superconducting magnetic energy storage (SMES)...
Screening currents induced in HTS coils generate an irregular magnetic field. In particular, a large amount of screening currents are induced in REBCO tapes due to the tape shape, consequently a large screening current-induced fields is produced. Screening current-induced fields are a crucial problem for NMR/MRI applications. However, it is not easy to estimate screening current-induced fields...
In order to elucidate AC loss characteristics of High-Tc superconducting coils wound by stacked conductors, we measured AC losses of Bi-2223 sample coils under the various electro-magnetic conditions by a nitrogen boil-off method. The sample coils were wound by stacked conductors, which were composed of two Bi-2223 tapes. Each tape of stacked conductors was wrapped with the polyimide tape, and...
Quasi-isotropic strands made of second generation (2G) wires are regarded as promising cables for large high field magnets in virtue of their high current capacity and well mechanical property. During the charge of the magnet, quasi-isotropic strands in use will subject to magnetic field and inevitably produce alternating current (AC) loss, which has important impacts on the magnet operation. ...
For ac applications of superconductors, ac loss is most of the heat load. So it is very important to estimate the ac losses in superconducting windings for the design of cooling system. However the measurement of ac loss takes much time and cost and also needs large facilities. So simple and easy estimation method of ac loss is required. In this study we investigated the ac loss properties of...
REBCO superconducting tapes have great performance in critical current density, Jc, property even at liquid nitrogen temperature. However, it is necessary to enhance a current capacity according to various applications. We proposed the configuration of parallel conductors. The constituent strands of parallel conductors need to be insulated and transposed for even current sharing and low ac...
When coated conductors are applied to devices whose transport current or applied magnetic field is time-dependent, ac loss in coils is a major issue which needs to be accurately evaluated and addressed. Electromagnetic field analyses are effective tools not only for evaluating and characterizing ac losses in entire coils wound with coated conductors, but also for estimating the ac loss density...
(RE)BCO commercial coated superconductors have gained an increasing interest for its use in high magnetic field magnets. The leading project is the 32 T DC user magnet to be commissioned soon at the National High Magnetic Field Laboratory, Florida, USA. This state-of-the-art high field all-superconducting magnet, bath-cooled at 4.2 K, is comprised of a two-coil insert pancake-wound with...
In the circumstances of the bulk transport of current lead in a magnet, HTS DC cables used as current leads for the magnets have great advantages. However, the AC loss is one of the important parameters of HTS DC cable and it has a strong effect on its stability and operation cost. For this research, a cold dielectric HTS DC cable, consisting of one conductor layer, one insulation layer and...
In automatically wound machines, the actual position of each single conductor in the slot is usually unknown. However, depending on the individual placement in the slot, parallel-connected strands can lead to differing circulating currents. Since the flux-linkage due to leakage flux in the slot varies in radial direction, increasing towards the slot opening, the induced voltage also differs in...
Assembled coated conductors are essential in many high current HTS applications. There are two ways to achieve assembled coated conductors. One way is to vertically stack the coated conductors, and the other is to use continuously transposed Roebel cables. In addition to high current carrying capacity, Roebel cables offer both low AC loss and mechanical flexibility. In this work, we measured...
The high temperature superconducting (HTS) conductors with low AC losses are essential for the HTS power devices. There are many studies for the development of 2G HTS conductor with the low AC loss and large current capacity, such as Roebel assembled coated conductors (RACC), conductors on round core (CORC), twisted stacked tape cable (TSTC), coated conductor Rutherford cable (CCRC), and so...
The cable-in-conduit conductor (CICC) that will be adopted for the 3L module of the ITER Central Solenoid (CS) coil and for the Toroidal Field (TF) magnets of the ITER Machine have been extensively characterized in the SULTAN facility in Villigen, Switzerland by means of DC and AC tests. The AC tests were performed superimposing a sinusoidally varying magnetic field, with amplitude of 0.2−0.3...
The magnetization loss model in HTS tape when the magnetic field is exposed to the HTS tape face is suggested to be a Brandt model. In the case of a thin HTS tape, when the magnetic field exposed perpendicular to the HTS tape axis and the tape face is rotated, the magnetization losses correspond with Brandt model when the linkage magnetic field exposed. We previously reported the AC loss...
Brushless doubly fed machine (BDFM) is a new type of adjustable-speed machine developed in recent years. It has broad application prospects in the field of variable frequency speed regulation and wind power generation. However, the traditional loss calculation method is no longer applicable due to the special structure and complex magnetic field distribution of BDFM. A novel hybrid rotor...
High temperature superconducting (HTS) wires such as first generation Bi-2223 Ag-sheathed tape and second generation rare-earth-based coated conductor have been developed and become commercially available. When the HTS coils wound using these wires are energized, the in-plane screening currents induced in the windings due to the perpendicular components of locally applied magnetic fields not...