Improvement of the Magnetization of a Superconducting Bulk using an Iron Core

Kapek

Colle

et al. 2018

Abstract-In this work, we propose to study and design a coil used to magnetize, by means of a Pulsed Field Magnetization (PFM) process, an inductor of a radial flux superconducting machine with one pair of poles. Each pole contains four similar HTS bulks of 30 mm diameter arranged in a square pattern. The cryostat already exists for this application and the temperature of the HTS bulks can vary from 4.2 K to their critical temperature, in transient state. For a given primary source of energy, here a capacitor bank of 10 kJ (5 mF, 2 kV) is available, the PFM process depends strongly on the value of the coil inductance used to generate pulsed field, because it defines the waveform of the current: peak value and time constant. Thus, 3D modeling of the coil is required in order to be sure that its inductance and the magnetic field produced will provide a full magnetization of HTS bulks. From the practical point of view, we would like to achieve an average magnetization of each pole around 3 T.In this paper, numerical modeling of coils with different number of turns coupled with circuit's equations is achieved. The maximum magnetic field obtained on the HTS bulks and estimated magnetization at the top center of each HTS bulk, are presented and discussed.

Section: B Description Of the Impulse Magnetizermentioning

confidence: 99%

“…In previous works, coils have successfully been realized for magnetizing one single HTS pellet by using copper foils of 0.2 mm or 0.5 mm thickness, and the same width as the HTS bulk height [23]. The coils to be modelled in the present study, will respect the same criteria.…”

Section: B 3d Modeling Of the Magnetization Of The Inductormentioning

confidence: 99%

3-D Modeling of Coils for Pulsed Field Magnetization of HTS Bulk Pellets in an Electrical Machine

Kapek

Colle

et al. 2018

“…The coefficients of the regions I to IV are related to (12), (13), (14), (15), (16), by using the Fourier series method, and rewriting equations in matrix and vectors format: 04 11 1 3 1 3 12 1 3 04 04 13 1 3 21 0 3 0 3 04 22 0 3 23 0 3 32 1 2 33 1 2 34 1 2 35 1 2 42 0 2 43 0 2 44 0 2 45 0 2 ,,…”

Section: Interface Conditions Between the Regionsmentioning

confidence: 99%

“…To be realistic, the axial length e of the air-gap is now of 20 mm and the current density Ja in the coil depends on time. This current density is assumed to be produced by the discharge of a capacitor bank [15], [16] as:…”

Section: Example Of Pfm Of a Bulk Htsmentioning

confidence: 99%

Analytical Modeling of an Inductor in a Magnetic Circuit for Pulsed Field Magnetization of HTS Bulks

Elbaa

Douine

et al. 2018

The development of bulk magnets based on REBCO type superconductors that can generate up to 17 T requires the implementation of a magnetization system, sometimes pulsed. Therefore, at least one coil around the High Temperature Superconducting (HTS) bulk is required. In this paper, we suggest an analytical approach in order to assess the magnetic vector potential and to compute the inductance of a coil having a rectangular crosssection and concentric with a magnetic circuit including an air-gap. On a proposed geometry, analytical results are compared with those obtained by using Finite Element Analysis (FEA). The gained analytical expressions give accurate results with an error less than 1% on the inductance value of the coil. The induced current density and trapped magnetic field in a HTS bulk during a Pulsed Field Magnetization (PFM) are also calculated using the proposed analytical expressions of the magnetic vector potential combined with an integral method. The achieved results show a remarkable match with those obtained with COMSOL.

“…a Pulsed Field Magnetization (PFM). We have studied in previous works, the PFM process [11] and the influence of an iron core on the Trapped Magnetic Field (TMF) in [12].…”

Section: Introductionmentioning

confidence: 99%

Magnetization and Demagnetization Studies of an HTS Bulk in an Iron Core

Gony

Douine

et al. 2016

High Temperature Superconductors (HTS) are promising materials in variety of practical applications due to their ability to act as powerful permanent magnets. Thus, in this paper, we have studied the influence of some pulsed and pulsating magnetic fields applied to a magnetized HTS bulk sample. The bulk sample, the iron core, the two inductors and the current sources used to magnetize and demagnetize the superconducting bulk in the iron core are presented. Then, we detail various magnetizing and demagnetizing processes, and their purposes. For the magnetization studies, we have shown that there is no significant difference between the Successive Process and the Direct Process of magnetization. The maximum Trapped Magnetic Field (TMF) is about 1 T, 10 min after the magnetization process. For the demagnetization studies, we propose many results as a hysteresis loop corresponding to the pulsed demagnetizing field influence. Various time evolutions of the TMF are also shown: when the demagnetizing AC field is applied a few minutes after or several days after the magnetization. This leads to completely different results, from 5 % / min to 1 % / (6 hours) of reduction of the TMF. The results presented here, give many practical information to users of superconducting bulk magnets. We assume that decreasing the temperature will increase the capabilities of trapping the magnetic field. We conclude that a strong interest must be kept on the applications of HTS bulks in Electrical Engineering, preferably at lower temperature than 77 K.