Ainslie, Mark

Badcock, Rod

Bumby, Chris

Mataira, Ratu

Queval, Loic

Apollo (Cambridge)

Thermal model (when included):Heat source, Q = E·JAssumed thermal properties for YBCO, copper & Hastelloy substrate from reference data publishedin Zhang et al. J. Appl. Phys. 112, 043912 (2012)2-LP-SMA-S07:Modelling an HTS dynamo using a segregated finite-element modelMark D. Ainslie1, Loïc Quéval2, Ratu C. Mataira3 , Rod A. Badcock3, Chris W. Bumby31) Bulk Superconductivity Group, Department of Engineering, University of Cambridge, UK2) Group of Electrical Engineering Paris (GeePs), CentraleSupélec, University of Paris-Saclay, France3) Robinson Research Institute, Victoria University of Wellington, New ZealandModelling ResultsModelling FrameworkE0 = 10-4 V/mCurrent constraint (open-circuit):Measured Jc(B,θ) characteristics (left) & n(B,θ) (right)for the SuperPower SCS4050-AP HTS wireSegregated finite-element model geometry:permanent magnet model, time-independent (left),HTS wire, time-dependent (right)Electromagnetic model:2D (infinitely long) H-formulationCOMSOL Multiphysics 5.3aExperimental results fromPantoja et al. IEEE TAS 28 5202205 (top)Pantoja et al. IEEE TAS 26 4805208 (bottom)Time-averaged DC voltage (2nd-10th cycles) for magnet frequencies, f = 10 – 500 HzPermanent magnet movement past the HTS wire is simulated using time-dependent boundary conditions &a translation operator for the magnet’s static magnetic field Electromagnetic boundary conditions:On outer boundary: H = Hext + Hselfwhere Hext(x,y,t)  = Tt HPM(x,y) = HPM(x+xM(t),y+yM(t))(xM,yM) is the time-dependent position of the HTS assembly relative to OHself is obtained by the 2D integration of the Biot-Savart law:Assumed wire properties:SCS4050-AP, width 4 mm, extrapolated to 12 mm for the modelIc ≈ 320 A (self-field)1 μm HTS layer, artificially expanded to 5 μm to improve computational speed50 μm substrate (Hastelloy), 266 nΩ·m25 μm top/bottom copper stabiliser, 3 nΩ·mFor the HTS wire only, the output increases linearly. The inclusion of generated heat reduces the output, this effect increasing with frequency.Including the whole wire architecture produces results observed in experiments: a linear output for low-f, a plateau & then reducing output for high-f.For high-f, current sharing between the layers in the HTS wire architecture become important; in particular, current flow into the Cu stabiliser due to excessive overcritical currents developing in the HTS layer.The numerical models give an important insight into what is occurring inside the HTS wire in the HTS dynamo.Cumulative, time-averaged DCvoltage for magnet frequencies,f = 10, 50, 100 & 500 Hz (HTS layer only)Experimental HTSdynamo schematicPermanent magnet properties:Br = 0.5 TWidth (wm) = length (L) = depth = 10 mmGap between wire & PM: 3 mmVoltage scaled by active magnet length, LCalculated open-circuit waveform fora magnet frequency, f = 10 Hz(HTS layer only)H = Hext + Hself

Modelling an HTS dynamo using a segregated finite-element model

https://www.repository.cam.ac.uk/bitstream/handle/1810/297950/EUCAS%202019%20Poster%20final.pdf?sequence=1&isAllowed=y

Modelling an HTS dynamo using a segregated finite-element model

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