Design and Characteristic Analysis of a Homopolar Synchronous Machine Using a NI HTS Field Coil

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.

Superconducting Electric Power Systems: R&D Advancements

“…In Ref. [18], the authors investigate the charge/discharge problem of NI HTS coils used in an HTS homopolar synchronous machines, Figure 6. Firstly, the authors compare the charging/discharging performances of four coil configurations: (a) with turn-to-turn insulation, (b) no-insulation, (c) insulation every eight turns, and (d) insulation every four turns.…”

“…This editorial paper presents and discusses the R&D and tests of superconducting technologies that aim to demonstrate the performance of this technology in electric power systems for more efficient use of energy. The editorial covers: [16][17][18][19][20].…”

Synchronous Homopolar Generator without Permanent Magnets for Railway Passenger Cars

“…For this reason, a number of numerical calculation methods have been proposed for SHMs, taking into account the saturation of the magnetic circuit, including threedimensional FEA [17][18][19], two-dimensional FEA [9,20], one-dimensional magnetic circuits, and their various combinations [21,22]. In Reference [9], a simplified SHM modeling technique was proposed, in which the features of the SHM magnetic field are taken into account in a two-dimensional model by introducing the excitation field term into the equations of the magnetic vector potential and solving the 2D magnetostatic problems complemented with an equivalent circuit equation for the excitation flux.…”