A half-bridge HTS transformer–rectifier flux pump with two AC field-controlled switches

Gawith, James; Geng, Jianzhao; Li, C; Shen, Boyang; Zhang, X; Ma, Jun; Coombs, Tim

doi:10.1088/1361-6668/aac86d

Cited by 26 publications

(13 citation statements)

References 23 publications

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“…In the applications of dynamic resistance such as persistent current switches [7][8][9][10] and flux pumps [11][12][13][14][15][16][17][18][19][20][21][22], losses are a very important issue. It would be desirable to know the sources of the losses and to minimize them.…”

Section: Loss Analysismentioning

confidence: 99%

“…The DC voltage arises from the interaction between the transport DC current and moving magnetic fluxons within the superconductor, which is a modulation of the vortex spatial distribution [4]. Dynamic resistance is very useful and is utilized as a key mechanism in persistent current switches [7][8][9][10] and HTS flux pumps [11][12][13][14][15][16][17][18][19][20][21][22]. It is also very common for a DC carrying coated conductor to work in an external AC magnetic field, such as in HTS motors and generators [23][24][25][26], levitation [27,28], and HTS power cables [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

“…The impact of the Cu-stabilizer incurred by these multiple effects has been analysed, including on dynamic resistance, dynamic voltage, losses, and the risk of quench of the HTS CC. The work is indicative in designing ac magnetic field controlled persistent current switches [7][8][9][10] and flux pumps [11][12][13][14][15][16][17][18][19][20][21][22], in terms of increasing the off-state resistance, analyzing different sources of losses, minimizing detrimental losses, and enhancing safety and stability.…”

Section: Introductionmentioning

confidence: 99%

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A temperature-dependent multilayer model for direct current carrying HTS coated-conductors under perpendicular AC magnetic fields

Geng

Chan

et al. 2020

Supercond. Sci. Technol.

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When a type II superconductor carrying a direct current is subjected to a perpendicular oscillating magnetic field, a direct current (DC) voltage will appear. This voltage can either result from dynamic resistance effect or from flux flow effect, or both. The temperature variation in the superconductor plays an important role in the nature of the voltage, and there has been little study of this so far. This paper presents and experimentally verifies a 2D temperature-dependent multilayer model of the second generation (2G) high temperature superconducting (HTS) coated conductors (CC), which is based on H-formulation and a general heat transfer equation. The model has coupled the electromagnetic and thermal physics, and it can simulate the behavior of 2G HTS coated conductors in various working conditions where the temperature rise has a significant impact. Representative electromagnetic phenomena such as the dynamic resistance effect and the flux flow effect, and thermal behavior like quench and recovery have been simulated. This thermal-coupled model is a powerful tool to study the thermal-electromagnetic behaviors of 2G HTS coated conductors in different working conditions, especially when the impact of temperature rise is important. This multilayer model is also very useful in analyzing the impact of different layers in the 2G HTS CCs, especially the metal stabilizer layers. It has been proven to be a very powerful tool to help understand more complicated characteristics in the CCs which could not be accurately measured or simulated by previous numerical models. The work is indicative and very useful in designing ac magnetic field controlled persistent current switches and flux pumps, in terms of increasing the off-state resistance, analyzing different sources of losses, minimizing detrimental losses, and enhancing the safety and stability.

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Section: Loss Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A temperature-dependent multilayer model for direct current carrying HTS coated-conductors under perpendicular AC magnetic fields

Geng

Chan

et al. 2020

Supercond. Sci. Technol.

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“…Similar protection techniques have been suggested in the past for both LTS and high temperature superconducting (HTS) magnets where normal zones are induced by local AC-loss or by locally increasing the magnetic field using an external coil [1], [5], [6], [7]. Such system shows as well similarities with a method of switching conductors from their superconducting state to a resistive state for superconducting switches in HTS flux pumps as described in [8], [9].…”

Section: Introductionmentioning

confidence: 90%

External Coil Coupled Loss Induced Quench (E-CLIQ) System for the Protection of LTS Magnets

Mulder

Bordini

Ravaioli

et al. 2023

IEEE Trans. Appl. Supercond.

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The next generation of Nb3Sn accelerator magnets are pushed to higher magnetic fields, higher stored energy and higher energy density. This brings additional challenges when it comes to quench protection. At CERN, a fast quench protection system is under development that introduces normal zones directly in the coil's conductor by inductive heating. This system is called External coil Coupled Loss Induced Quench (E-CLIQ). The E-CLIQ device comprises many small copper coils that are strategically placed near the main coils. Once a quench is detected, a capacitor is discharged in to the E-CLIQ coils, resulting in the characteristic damped oscillating current of an RLC circuit. This results in a large, but local applied dB/dt on the conductor of the main magnet system, which locally heats it by induced interfilament and interstrand coupling loss. Such a system has the advantage of being fast by introducing normal zones in potentially less than 10 ms, it doesn't rely on heat flow through the insulation layers of the coil, as is the case with traditional quench heaters, and it is not electrically connected to the main circuit.In this paper, the E-CLIQ system is introduced, several first demonstrator coils are presented and the results of a first proofof-concept test are shown.

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“…1. In either case, the flux pump can be closely modelled using a simple circuit topology [25]. The transformer wirelessly transfers ac current from a room temperature primary to a superconducting secondary.…”

Section: Introductionmentioning

confidence: 99%

Design of a 60 kA Flux Pump for Fusion Toroidal Field Coils

Rice

Geng

Bumby

et al. 2022

IEEE Trans. Appl. Supercond.

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High-temperature superconducting (HTS) magnets offer a novel pathway to magnetically confined fusion energy generation. Reactor-scale fusion devices require tens of kA of current to generate large toroidal fields for magnetic confinement.Operating HTS magnets at kA-current levels is difficult due to unavoidable joint resistances that require active driving of current. The large footprint and energy demand of a solidstate power supply and multi-kA current leads present significant constraints on the size, cost and efficiency of a fusion tokamak. An alternative approach is to use an HTS flux pump, which can generate and sustain persistent currents in HTS coils at the kAlevels required by fusion magnet systems. Here, we outline the design of a 60 kA transformer-rectifier flux pump for energizing and sustaining an 80 mH HTS fusion magnet. The flux pump is driven by an iron-core transformer with copper primary and HTS secondary windings. This is rectified by switching elements in the superconducting circuit into a uni-directional dc voltage output which charges the inductive load. To charge the load coil to 60 kA in 24 hours, an output dc voltage of 55 mV is needed. However, only 6 mV is required to maintain a long-term steady current of 60 kA. Such a device can significantly reduce the cost and footprint of future fusion reactor designs.

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A half-bridge HTS transformer–rectifier flux pump with two AC field-controlled switches

Cited by 26 publications

References 23 publications

A temperature-dependent multilayer model for direct current carrying HTS coated-conductors under perpendicular AC magnetic fields

A temperature-dependent multilayer model for direct current carrying HTS coated-conductors under perpendicular AC magnetic fields

External Coil Coupled Loss Induced Quench (E-CLIQ) System for the Protection of LTS Magnets

Design of a 60 kA Flux Pump for Fusion Toroidal Field Coils

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