Abstract
In this thesis, the results of a study on the feasibility of using rare-earth barium copper oxide (ReBCO) high-temperature superconducting coils as the magnetic field windings of a high-dynamic linear motor system are reported. The associated electromagnetic, thermal and mechanical challenges are explored, with the first two in particular related to AC loss. ReBCO coils can produce a significantly stronger magnetic field than conventional electro- or permanent magnets, enabling a higher force density.
Superconductors such as ReBCO can transport a direct current practically without dissipation. Although the envisioned stator coils of a linear motor carry a direct current, they are exposed to the rapidly time-varying magnetic field produced by the alternating current in the mover coils. Therefore it imposes a thermal load in the form of AC loss on the superconducting stator coils, in addition to the mechanical load in the form of Lorentz forces. In this work, we investigate the magnitude of the various contributions to the total heat load, select viable cryogenic cooling methods, study AC loss under motor-relevant conditions and assess the mechanical stress distribution inside representative superconducting coils.
As a general conclusion, in this work no showstoppers were encountered that prevent the use of present ReBCO tape as the material for the superconducting stator coil windings in a high-dynamic linear motor system. A dedicated experimental set-up was designed and fabricated to measure AC loss in representative ReBCO racetrack coils, carrying a direct current, in an external time-varying magnetic field. Even with state-of-the-art commercial tape material, the heat loads are estimated to be manageable, and adequate cryostat concepts comprising off-the-shelf components are available. The effect of the significant and rapidly varying mechanical loads on ReBCO coils is still an area of research that needs further exploration. Nonetheless, it is expected that also here the stress state of the coils can be ‘engineered’ to meet the requirements of future high-dynamic motor systems.
Superconductors such as ReBCO can transport a direct current practically without dissipation. Although the envisioned stator coils of a linear motor carry a direct current, they are exposed to the rapidly time-varying magnetic field produced by the alternating current in the mover coils. Therefore it imposes a thermal load in the form of AC loss on the superconducting stator coils, in addition to the mechanical load in the form of Lorentz forces. In this work, we investigate the magnitude of the various contributions to the total heat load, select viable cryogenic cooling methods, study AC loss under motor-relevant conditions and assess the mechanical stress distribution inside representative superconducting coils.
As a general conclusion, in this work no showstoppers were encountered that prevent the use of present ReBCO tape as the material for the superconducting stator coil windings in a high-dynamic linear motor system. A dedicated experimental set-up was designed and fabricated to measure AC loss in representative ReBCO racetrack coils, carrying a direct current, in an external time-varying magnetic field. Even with state-of-the-art commercial tape material, the heat loads are estimated to be manageable, and adequate cryostat concepts comprising off-the-shelf components are available. The effect of the significant and rapidly varying mechanical loads on ReBCO coils is still an area of research that needs further exploration. Nonetheless, it is expected that also here the stress state of the coils can be ‘engineered’ to meet the requirements of future high-dynamic motor systems.
| Original language | English |
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| Qualification | Doctor of Philosophy |
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| Award date | 4 Oct 2024 |
| Place of Publication | Enschede |
| Publisher | |
| Print ISBNs | 978-90-365-6252-2 |
| Electronic ISBNs | 978-90-365-6253-9 |
| DOIs | |
| Publication status | Published - Oct 2024 |