Total AC loss study of 2G HTS coils for fully HTS machine applications

Zhang, Min; Yuan, Weijia; Kvitkovič, J.; Pamidi, Sastry

doi:10.1088/0953-2048/28/11/115011

Cited by 62 publications

(44 citation statements)

References 34 publications

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“…The details of the model can be found in [26]. The electromagnetic part of the model is described by the so-called H-formulation, which is a well demonstrated approach for evaluating the AC loss of HTS [27], [28], [29], [30]. The Maxwell's equations are solved for variables Hx and Hy in the 2D planar model with the E-J power law [31],…”

Section: Model Descriptionmentioning

confidence: 99%

Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

Zou

Zermeño

Baškys

et al. 2016

Supercond. Sci. Technol.

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High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (<2 T), so they show potential for improving the performance of many electrical applications that use permanent magnets like rotating machines. Towards practical or commercial use of TFMs, effective in situ magnetization is one of the key issues. The pulsed field magnetization (PFM) is among the most promising magnetization methods in virtue of its compactness, mobility and low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electromagnetic-thermal coupled model with comprehensive temperature dependent parameters is used to simulate a stack of CCs magnetized by successive magnetic pulses. An overall picture is built to show how the trapped field and flux evolve with different pulse sequences and the evolution patterns are analyzed. Based on the discussion, an operable magnetization strategy of PFM with successive pulses is suggested to provide more trapped field and flux. Finally, experimental results of a stack of CCs magnetized by typical pulse sequences are presented for demonstration.

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Section: Model Descriptionmentioning

confidence: 99%

Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

Zou

Zermeño

Baškys

et al. 2016

Supercond. Sci. Technol.

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“…This part of dissipated heat should be carefully removed. There are several models to estimate the AC losses of the traditional INS coil [9], but the models to estimate the AC losses of the NI coil are not applicable since the NI coil provide an alternative radial path to bypass the AC current away from the original spiral path. Therefore, this paper will investigate the differences of AC losses between these two coil winding techniques in order to aid coil cooling design.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Zhang

Kim

et al. 2016

J Supercond Nov Magn

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A single pancake coil without turn-to-turn insulation was tested in this paper to investigate the transient responses under different situations. We performed charging and discharging test, AC current test, and regional quench emulation test on the non-insulated (NI) coil. The experimental test results show a significant time delay for charging and discharging characteristics of NI coil and can be validated by a simple proposed equivalent electrical circuit. Under the AC operating current, the NI coil can bypass nearly all the AC current from the coil spiral path to the radial path such that it is not possible for NI coil to store or be affected by the AC magnet field. Additionally, while carrying AC current, the AC loss dissipation of NI coil is inversely proportional to the frequency of the AC operating current. When a regional quench occurs, the NI coil can bypass the current in the regional quench zone to avoid further temperature accumulated and protect the NI coil itself.

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“…Furthermore, intensive AC loss analysis of HTS coils has been carried out both experimentally and numerically [14][15][16][17][18][19][20]. However, there has been no report to date on the influence of asymmetric wire critical current on coil AC loss.…”

Section: Introductionmentioning

confidence: 99%

Exploiting asymmetric wire critical current for the reduction of AC loss in HTS coil windings

et al. 2019

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Critical current and AC loss in coil windings are two important factors for various HTS applications. Many coated conductors exhibit asymmetry in the variation of the critical current with magnetic field angle. This asymmetry results in different coil critical current values depending on the orientation of the conductors in the coil windings. We report critical current and AC loss results at 77 K and 65 K for three hybrid coil assemblies which have a common central winding and different arrangements of the end windings. We found a difference greater than 13% in both the critical current and the AC loss results for the different arrangements. The results imply that if we wind coil assemblies smartly even using the same materials and the same design, we can not only improve critical current but also reduce AC loss significantly.

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Total AC loss study of 2G HTS coils for fully HTS machine applications

Cited by 62 publications

References 34 publications

Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

An Experimental Investigation of the Transient Response of HTS Non-insulation Coil

Exploiting asymmetric wire critical current for the reduction of AC loss in HTS coil windings

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