Air-gap Armature Winding Research Articles

High-Temperature Superconducting Homopolar Inductor Alternator for Marine Applications

This paper describes a high power density high-temperature superconducting (HTS) electric machine topology that is scalable for marine propulsion and power generation. The design, currently being pursued for airborne applications, is based on homopolar inductor alternator (HIA) technology, which is new within HTS applications. The basic machine design configuration of the HTS HIA is based on a stationary HTS field excitation coil, a solid rotor, and an advanced but conventional stator comprising liquid-cooled air-gap armature winding and an advanced iron core. High power density is obtained by the enhanced magneto-motive force capability of the HTS coil, the increased airgap flux density and armature current loading, and the high tip velocity of the rotor. Preliminary scaled up designs look attractive for three marine applications: propulsion drive, primary ship power generation, and power generation modules. The generators are driven directly by the turbines without the additional complexity of a clutch and gear system. A conceptual design study of a 36-MW 3600-r/min generator, a 4-MW 7000-r/min auxiliary generator, and a 36-MW 120-r/min and 4-MW 132-r/min propulsion motor are summarized.

Design and electrical characteristics analysis of 100 HP HTS synchronous motor in 21st century frontier project, Korea

A 100 hp class superconducting motor in the 21st Century Frontier R&D Program of Korea has been designed. A theoretical model of high temperature superconducting (HTS) motor was presented by two-dimensional electromagnetic field analysis. The motor is composed of HTS field winding, cold damper shield, air-gap armature winding and laminated machine shield. The HTS field winding consists of racetrack type double pancake coils wound with Bi-2223 HTS tapes operated at about 30 K. The operating current of the HTS tape conductor could be determined by the magnetic field distribution calculated in the HTS field winding and the I/sub c/ - B characteristics of a practical HTS conductor, taking account of its anisotropy.

Development of a 70 MW class superconducting generator

A national project to develop a superconducting generator was begun in 1988 in Japan under the New Sunshine Project of AIST, MITI. This generator has merits of higher efficiency and compactness for transmission lines. A 70 MW class superconducting generator is the goal of the project. The authors have been developing a rotor having a superconducting field winding and a stator having an air-gap armature winding. The field winding was designed to be cryostable so as to recover from a partial transition to normal conduction. The field winding was tested in a nonrotating cryostat, and excitation performance and stability were confirmed to be enough for the 70 MW class superconducting generator. The rotor and the stator have been completed and a shop test is being made.

Development of 70 MW class superconducting generators

In Japan, the Engineering Research Association for Superconductive Generation Equipment and Materials (Super-GM) has been conducting R&D since FY 1988 on 70-MW class model machines in an effort to realize a 200 MW class pilot machine commissioned as part of the Moonlight Project 'Development of Superconductivity Technology for Application to Power Apparatuses'. The authors describe the recent development of superconducting generators in Super-GM. It is noted that the R&D on superconducting generators by Super-GM which started in FY 1988 is progressing from the research stage of element techniques to the verification of manufacturing techniques using various partial models such as field winding models, multi-cylindrical rotor, damper model, air-gap armature winding, rotating cooling model, and helium transfer coupling. >

Development of 70 MW class superconducting generators

This paper describes recent results of the R&D on the 70 MW class superconducting generator in Super-GM, according to an 11-year period program since 1988.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ten MVA air-gap armature winding: thermal, structural and dielectric results

This paper describes the armature winding built as part of MIT's 10 MVA superconducting generator project. The winding has a helical winding form, is an air-gap winding having no iron teeth in the active region, employs a limited voltage gradient insulation scheme and is cooled by an insulating fluid. Structurally, the winding employs bonded joints between the conductors and structural tubes, which are of filament-wound fiber-reinforced plastic. Preliminary tests indicated that thermal performance of this winding was satisfactory. On the other hand, the winding suffered a catastrophic insulation failure after only a short time at high voltage. The resulting fault gave the structural system of the armature winding (and the rest of the machine) a good test. In this paper the authors review the major aspects of the design of the winding, describe the thermal tests and then tell of the insulation failure. They can, at best, speculate about the cause of that failure, but they can, on the basis of this experience, make recommendations for further development of machines of this type.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Practical design of superconducting generator—electrical characteristics equations

A superconducting generator (SCG) consists of a nonmagnetic cryogenic rotor, which contains a super-conducting field winding cooled by liquid helium, and an airgap armature winding, which makes it possible to obtain a high magnetic field in the airgap. Since the SCG construction differs from that of the conventional generator, practical application requires that its electrical and mechanical design methods be established. This paper describes electrical characteristics equations of the SCG, electromagnetic shield characteristics of double dampers and proof test results of a 50-MVA experimental SCG. Equations for the generator parameters (voltages, output capacity, reactances, time constants, flux densities), which are useful for the practical design of the SCG, are derived from two-dimensional electromagnetic analysis considering winding thickness and the edge effect. From comparison with measured and calculated values of no-load, sudden 1–3 phase short-circuit and slip extended tests, these equations were confirmed as valid.

Practical Design of Superconducting Generator. Electrical and mechanical design.

Since a superconducting generator (SCG) consists of a superconducting field winding, a nonmagnetic cryogenic rotor and an airgap armature winding, its design method differs from that of the conventional generator. Practical applications require establishment of its electrical and mechanical design methods.A design flowchart of the SCG was shown and the basic design method was clarified. For this method, the electrical and mechanical design of a 50MVA experimental generator was carried out. Its design specifications and size were compared with a future 1, 120MVA generator and a 778MVA conventional generator. Furthermore, synthetic stress applied on the main rotor components, such as the torque tube and room temperature damper, was obtained. From the test results of generator power loss and the V curve under synchronous condenser operation, the design method was proved to be valid.

Development of 70 MW class superconducting generators

In Japan, the Engineering Research Association for Superconductive Generation Equipment and Materials (Super-GM) has been conducting R&D since FY 1988 on 70-MW class model machines in an effort to realize a 200 MW class pilot machine commissioned as part of the Moonlight Project 'Development of Superconductivity Technology for Application to Power Apparatuses'. The authors describe the recent development of superconducting generators in Super-GM. It is noted that the R&D on superconducting generators by Super-GM which started in FY 1988 is progressing from the research stage of element techniques to the verification of manufacturing techniques using various partial models such as field winding models, multi-cylindrical rotor, damper model, air-gap armature winding, rotating cooling model, and helium transfer coupling.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Practical Design of Superconducting Generator. Electrical Characteristics Equations.

A superconducting generator (SCG) consists of a non-magnetic cryogenic rotor, which contains a superconducting field winding cooled by liquid helium, and an airgap armature winding, which makes it possible to get a high magnetic field in the airgap. Since the SCG construction differs from that of the conventional generator, practical application requires that its electrical and mechanical design methods be established.This paper describes electrical characteristics equations of the SCG, electromagnetic shield characteristics of double dampers and proof test results of a 50 MVA experimental SCG. Equations for the generator parameters (voltages, output capacity, reactances, time constants, flux densities), which are useful for practical design of the SCG, are derived from two dimensional electromagnetic analysis considering winding thickness and the edge effect. From comparison with measured and calculated values of no-load, sudden 1-3 phase short-circuit and slip extended tests, these equations were confirmed as valid.

超電導発電機の研究開発状況

The application of superconducting technologies to electric power apparatuses is very important from the viewpoint of not only the promotion of energy and resources saving but also the improvement of power system stability. Super-GM was established in September, 1987 in order to proceed the research and development (R & D) on application of superconducting technologies to power apparatuses and Super-GM R & D project, which is sponsored by New Energy and Industrial Technology Development Organization (NEDO) under the Moonlight Project of Industrial Science and Technology, Ministry of International Trade and Industry, started from FY 1988 for a scheduled period of eight years. As to R & D on superconducting generator, the basic designs and analyses of 70MW class model machines and the research on element techniques concerning superconducting field winding, structural materials of multi-cylindrical rotor, warm damper, rotating cooling characteristics, helium transfer coupling and air gap armature winding of superconducting generator were conducted in FY 1988 and 1989, and many basic results were obtained. At present, R & D step is proceeding steadily from the research on element techniques to the examinations for manufacturing techniques using partial models such as field winding model, multi-cylindrical roter model, rotating cooling model, helium transfer coupling model and armature winding model for the manufactures and demonstration tests of 70MW class model machines. In this paper, the current situation of R & D on superconducting generator carried out by Super-GM is presented.

Performance evaluations of 50 MVA airgap winding stator for superconducting generator

Structural features of a trial-manufactured air-gap winding stator for a 50 MVA superconducting generator and results of various characteristic tests are described. The stator has an improved winding section, strengthened against electromagnetic force and smaller due to use of a four-layer water-cooled helical air-gap armature winding. The axial flux through the stator core, assumed to be generated by the circumferential current of the helical winding, is too low to pose any practical problems, as shown by a three-dimensional magnetic-field analysis taking into account the magnetic anisotropy due to the laminated iron core. The air-gap armature winding electromagnetic force in the radial and axial directions (which does not contribute to the generator output) increases when the running power factor decreases. The helical winding is shown to be applicable to the armature winding of large superconducting generators.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Development of superconducting AC generator

A 50-MVA superconducting generator was manufactured and tested. It was found that cool down of the rotor was completed smoothly in about 40 h and stable rotation was possible at 3600 r.p.m. The 50-MVA generator was connected to a power network without disturbance at synchronization, and it was successfully operated for 80 min as a synchronous condenser. The authors also discuss the design concepts for a 1000-MW superconducting generator. In this design superconducting field coils are put in twelve slots per pole and fixed by metallic wedges. Homogeneous damper, double bearing system and diamond airgap armature winding are adopted. On the basis of the 50-MVA test results and the 1000-MW design concept, a technical overview is presented of the possible development of such a 1000-MW generator.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Superconducting Rotor Development for a 50 MVA Generator

A superconducting rotor for a 50 MVA generatoi with a superconducting field winding was developed. This paper describes rotor development, and field winding static and rotating rotor excitation tests. Two electromagnetic damper shields, one for ambient temperature and the other for low temperature (50 K), were used to protect the field winding from time varying flux. The thermal strain that occurs between field winding supports and outer parts of the rotor body when a winding is cooled was prevented by providing individual supports for the winding and rotor body at one end of the rotor. The field winding was a concentrated saddle-shape type, inpregnated by epoxy. The rotor was tested using a small stator with an air gap armature winding. An output of voltage of about 1.5 kV and current of about 1.5 kA was obtained when a generating test was carried out at 3000 rpm.

Practical superconducting generators

A superconducting synchronous generator consists of superconducting field winding, nonmagnetic multi-tubular rotor and airgap armature winding. The superconducting generator has the benefits of 1/2-2/3 weight reduction and 0.5-0.8% efficiency improvement compared with the conventional generator, and the economic crossover between them appears to be 0.5-1.5 GVA.The problems discussed are (1) property, cooling and support of superconducting field winding, (2) thermal contraction of cryogenic torque tube, (3) tubular damper configuration, (4) seal of helium transfer coupling, (5) transposition, cooling and support of airgap armature winding, (6) vibration of the rotor.