Çok yüzeyli süperiletken ve halbach dizilimli sürekli mıknatıslardan oluşan süperiletken manyetik kaldırma sisteminin donmuş görüntü modeli ile analizi
Analysis of magnetic lift system consisting of multisurface superconductor and halbach arrangement continuous magnets with frozen image model
Yazar: AHMET FURKAN REİSOĞLU
Danışman: PROF. DR. AHMET CANSIZ ; PROF. DR. KEMAL ÖZTÜRK
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Elektrik Mühendisliği Ana Bilim Dalı / Elektrik Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering
Dizin: Kaldırma kuvveti = Lift force ; Manyetik etkileşme = Magnetic interaction ; Mıknatıslar = Magnets ; Süper iletkenler = Superconductors

Özet:
Yüksek sıcaklık süperiletkenleri tarafından sağlanan kaldırma kuvveti, araç uygulamaları için sınırlıdır. Süperiletken malzemelerin özellikleri sürekli olarak geliştirilmiş olsa bile, süperiletkenler ile manyetik kaldırma ve kılavuz sistemleri için verimli tasarım mekanizmaları bulmak oldukça zordur. Son on yılda yapılan çalışmalar çok yüzeyli süperiletken ve sürekli mıknatıs bileşenlerini optimum konfigürasyonlarda birleştirmenin kaldırma kuvvetlerini önemli ölçüde etkilediğini göstermiştir. Bu bağlamda, çok yüzeyli süperiletkenlerle etkileşime giren Halbach dizilimli sürekli mıknatıslar en çok kullanılan yöntemlerden biri haline gelmiştir. Bu tezde, çoklu süperiletken ve Halbach dizilimli sürekli mıknatıslar kullanılarak farklı konfigürasyonlar için araç gövdesi kaldırma sistemi oluşturulmuştur.
Konfigürasyonlar üç şekilde ele alınmıştır. Konfigürasyon 1'deki kaldırma sistemi bir mıknatıs ve bir süperiletkenden oluşmaktadır. Konfigürasyon 2'deki kaldırma sistemi Halbach dizilimli üç mıknatıs ve bir süperiletkenden oluşmaktadır. Konfigürasyon 3'deki kaldırma sistemi Halbach dizilimli üç mıknatıs ve üç süperiletkenden oluşmaktadır. Bu tezde söz konusu konfigürasyonlar inşa edildikten sonra havaya kaldırma ve kılavuz (yatay) kuvvetleri değişik süperiletken soğutma işlemlerine göre deneysel olarak ölçülmüş ve elde edilen sonuçların analizi donmuş görüntü modeli ile gerçekleştirilmiştir.
Kaldırma kuvvetinin artırılması, kılavuz ve araç gövdesi arasındaki kuvvet etkileşimlerine göre yukarıda anlatılan üç konfigürasyon için incelenmiştir. Mevcut konfigürasyonlar için düşey ve kılavuz kuvvetleri, manyetik dipol yaklaşımı ve donmuş görüntü modeli kullanılarak alanlı soğutma ve sıfır alan soğutma koşullarına göre hesaplanmıştır. Öngörülen kuvvet hesaplamaları, belirli ölçüm mesafeleri için analiz edilmiştir.
Bu çalışma vasıtasıyla manyetik kuvvet ile hareket eden araç sistemlerinde sürekli mıknatıs ve yüksek sıcaklık süperiletkenlerin sayısı ve dizilimlerinin kılavuz ve kaldırma kuvvetleri üzerinde belirli bir miktarda kazanç elde edilebileceği görülmüştür.

Abstract:
Energy is one of the most necessary vital needs for people to live in a certain standard in the world. For this reason, scientific studies on energy are very important for a sustainable life. Traditional methods such as oil and natural gas in energy production cause global warming. Many scientific studies are carried out in order to reduce the negative effects on the environment during the production, transportation and storage of energy. Superconductors, which have the potential to be used in energy production, transport, conversion, storage and many electrical vehicle applications, are an important scientific study in terms of minimizing the aforementioned negative environmental factors.
After the discovery of superconductivity, especially the limitations in cooling technologies did not provide much opportunity for the technological applications of the discovered superconductors. This situation continued until the eighties, although some alloys showing superconductivity at high temperatures were found, the temperature values were not at the desired levels. Thanks to the development of superconductors and the advancement of cooling technologies, advances have occurred in maglev (magnetic levitation) systems. Studies have been on the improvement of the lifting and steering vehicle parts of maglev systems.
Scientific studies conducted after the discovery of superconductivity showed that superconductivity is not only composed of zero resistance, but also revealed that superconductivity has a much more complex working mechanism than expected. Many experiments have been carried out on superconducting materials and it has been understood that these materials have different electrical and magnetic properties compared to normal conductors.
Initially, superconductivity was tried to be explained by starting from the theory of normal conductors, but the studies showed that a special theory of superconductivity should be developed. As a result of the researches, it has been determined that besides the zero resistance of the superconductors, their interactions with the magnetic field also differ from those of normal conductors. For example, it has been observed that superconductors exclude magnetic fields after the zero resistance property, known as the Meissner effect. A theory was developed by the London brothers in order to mathematically prove that superconductors have zero resistance and exclude magnetic fields.
In addition to making superconductors and their applications easier in our daily lives, it is obvious that integrating superconductors into processes that use fossil fuels such as oil, natural gas and coal that harm the environment in energy production, distribution and storage will minimize the damage to nature. The most important
reasons why superconductors are environmentally friendly is that they do not have adverse effects on the environment, such as energy and heat loss.
Making objects immune to the effects of gravity has been the common dream of science and researchers. Research on levitation using magnetic force has paved the way for train applications at speeds over 500 km per hour, and technological developments have accelerated with the emergence of superconducting materials. The modern development of magnetic transport systems known as magnetic levitation (Mag-Lev) began in the late 1960s as a corollary to the development of superconductor, transistor, and chip-based electronic control technology.
With the discovery of high temperature superconductors, YBCO started to be used in mag-lev systems after 1987. In the early days, difficulties were encountered in producing these superconductors in the form of wires due to their low current densities and their brittleness because they are ceramic. However, later on, techniques were developed and large-scale improvements were made in wire applications. On the other hand, it has been determined that superconductors produced in the form of ingots do not have such disadvantages and that they easily lift the magnets into the air, and thus, more focused on their lifting abilities.At this point, superconductor technology clearly shows that existing Mag-Mag-Lev transport systems will be developed with new high-temperature superconducting magnets in the coming years. With their passive, simple and promising properties, superconductors have superior qualities for technology. The development of systems that can move without contact, wear, liquid or gas intervention and without the need for active controls is an indication that they will be used in transportation and many other applications in the future.
The process of gaining superconductivity by cooling the superconducting material in an environment where there is no external magnetic field is known as zero field cooling in the literature. If a magnetic field is applied to the superconductor subjected to such a treatment by an external permangenet magnet, the magnetic flux is excluded by the superconductor. Conversely, when the superconducting material is in an environment where an external magnetic field exists before being cooled, the entire external magnetic field penetrates into the superconducting material. Naturally, the superconducting material is not superconducting before the cooling process takes place. The phenomenon of gaining superconductivity to the superconducting material by starting the cooling process when there is a magnetic field in the environment is also known as field cooling in the literature. After the cooling process is completed, the magnetic field in the superconductor is trapped in its place. The magnetic fluxes trapped in the superconductor are fixed in the non-superconducting centers. The regions where the flux is spiked consist of non-superconducting regions. These areas are called pinning centers. Flux nailing is required for stable superconducting levitation.
The force interaction between superconductors and magnets has been modeled by various methods. Examples of some of these are the magnetization model, the Maxwell stress tensor model, and the critical state model. For force estimates to be valid, the method must also take into account the effect of hysteresis in the superconductor. Using a particular method may not produce accurate results due to assumptions and limitations. In cases where hysteresis is not taken into account, the Ampere currents approximation or dipole moment approximation is one of the methods used together with the Frozen Image Model to determine the forces between the superconductor and permangenet magnet components. The frozen image model has been successfully applied in various superconducting levitation applications.
The relationship of forces between permanent magnets and high temperature superconductors is related to the flux spike and diamagnetic property of superconductors. Flux nailing ensures that the levitated superconductor or magnet is stabilized (nailing) and guiding (horizontal) forces so that it stays in the same place. The force interaction between the superconductor and the magnet can be modeled according to the dipole-dipole interaction approach because the currents in the superconductor behave like magnetic dipoles created by the magnetic field of the magnets. The interaction that takes place according to the dipole approach can be represented by the forces between the dipoles and their mirror images.
Since the work done in the thesis is experimental and on modeling, let's talk about our experimental setup.
The force measurement system is designed to provide sample control with 3 DC step (step) motors that allow 6-degrees of freedom movement from aluminum material. The measuring system also has a 3-axis load cell to measure the magnetic force at the relevant degree of freedom, a liquid nitrogen-cooled sample cup where superconducting materials are placed and can be changed to suit the multi-surface superconducting. The materials used in the force measurement system are the same, and the experiments were carried out in different configurations.
If we look at the stages of the experiments, we can divide the experiments into two as field cooling and zero field cooling experiments.In field cooling experiments, cooling is done by minimizing the distance between the permanent magnet and superconductors. Thus, when the superconductor is in the cooling phase, the magnetic field acts on it.In zero field cooling experiments, the distance between the permanent magnet and superconductors is brought to the maximum distance and cooling is done. Thus, the magnetic field does not affect the superconductor while it is in the cooling phase.
In this thesis, a vehicle body lifting system is constructed for different configurations by using multiple superconductors and Halbach array permanent magnets.
Three different configurations are taken into account in the thesis. The lifting system in Configuration 1 consists of a magnet and a supriconductor. The lifting system in Configuration 2 consists of three Halbach array magnets and a superconductor. The lifting system in Configuration 3 consists of three Halbach array magnets and three superconductors. In this thesis, after the aforementioned configurations were constructed, levitation and guidance (horizontal) forces were experimentally measured according to different superconductor cooling processes and the analysis of the obtained results was carried out with the frozen image model.
The increase in lift is investigated for the three configurations described above, based on the force interactions between the guide and the vehicle body. For the available configurations, the vertical and guide forces were calculated according to the field cooling and zero field cooling conditions using the magnetic dipole approximation and the frozen image model. The predicted force calculations have been analyzed for specific measuring distances.
Through this study, it has been seen that a certain amount of gain can be obtained on the guide and buoyancy forces of the number and arrangement of permanent magnets and high temperature superconductors in vehicle systems moving with magnetic force.