High temperature superconductor (HTS) machine is a promising candidate for the electrical aircraft propulsion, due to its great advantage on high power density. However, the HTS machine always suffers the problem of low thermal stability during quench. In this study, we apply a no-insulation (NI) coil technique on the rotor windings of HTS machines to enhance the stability and safety of the electrical aircraft. The NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through turn-to-turn contacts. This induced current and accompanying losses will considerably affect the practicality of this technique. To study this issue, an equivalent circuit network model is developed, and it is validated by experiments. Then analysis using this model show that most of induced current flows in the outermost turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher transport current induced and more significant accumulation of turn-to-turn loss. A grading turn-to-turn resistivity is proposed to reduce the transport current induced and AC loss accumulation and meanwhile keep the high thermal stability of the NI HTS coil. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments.
|Journal||IEEE Transactions on Transportation Electrification|
|Early online date||8 Jun 2020|
|Publication status||E-pub ahead of print - 8 Jun 2020|
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- Electrical Aircraft
- superconducting machine
- no-insulation coil
- AC loss
- ripple magnetic fields
Wang, Y., Wen, F., Li, J., Šouc, J., Gömöry, F., Zou, S., ... Yuan, W. (2020). No-insulation High Temperature Superconductor Winding Technique for Electrical Aircraft Propulsion. IEEE Transactions on Transportation Electrification, (In-press), (In-press). https://doi.org/10.1109/tte.2020.3000598