Abstract
This paper deals with a homopolar synchronous machine (HSM) applying high-temperature superconducting (HTS) field coils. Superconductors, especially high-temperature superconductors, have high potential as advanced materials for next-generation electrical machines due to their high critical current density and excellent mechanical strength. However, coils made with high-temperature superconductors have a high risk of being damaged in the event of a quench due to the intrinsic low normal zone propagation velocity (NZPV). Therefore, the coil protection issue has been regarded as one of the most important research fields in HTS coil applications. Currently, the most actively studied method for quench protection of the HTS coils is the no-insulation (NI) winding technique. The NI winding technique is a method of winding an HTS coil without inserting an insulating material between turns. This method can automatically bypass the current to the adjacent turn when a local quench occurs inside the HTS coil, greatly improving the operating stability of the HTS coils. Accordingly, many institutions are conducting research to develop advanced electrical machines using NI HTS coils. However, the NI HTS coil has its intrinsic charge/discharge delay problem, which makes it difficult to successfully develop electrical machines using the NI HTS coil. In this study, we investigated how this charging/discharging problem appeared when the NI HTS coil was used in an HTS homopolar synchronous machine (HSM) which is one of the electrical machines with a high possibility of applying the HTS coil in the future because it has a stationary field coil structure. For this, the characteristic resistances of HTS coils were experimentally obtained and applied to the simulation model.
Highlights
Published: 8 September 2021High-temperature superconducting (HTS) wires have excellent critical current and mechanical properties, making them suitable materials for high magnetic field applications.many studies are being carried out to apply high magnetic field coils made of high-temperature superconducting (HTS) wires to electrical machines such as motors and generators as well as analytical equipment such as NMR and MRI [1,2]
HTS coils are used as field windings in HTS motors and generators, and among them, they are being studied as field windings of synchronous machines due to the characteristics of superconductors that cause AC
These results show that the charging/discharging of the for the HTS coil which the insulating tape is2.8 inserted once every four turns, and the no-insulation coilincan be improved by about times by using the partial-insulation charging/discharging is the further improved.coil, These results method
Summary
High-temperature superconducting (HTS) wires have excellent critical current and mechanical properties, making them suitable materials for high magnetic field applications. The stationary HTS field coil structure enables very stable operation at high rotating speeds [15,16] Another advantage is that since the HTS field coil is not moved together by the rotation of the rotor core, the mechanical support structure can be simplified, and it can be free from epoxy impregnation of the HTS field coil. This makes it possible to apply the no-insulation winding method, which can dramatically improve the stability of the HTS field coil [17,18,19,20,21,22]. By applying these to the simulation model, the operating characteristics of the HTS HSM according to the winding method of the HTS field coil are analyzed
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