The torque analysis of coaxial magnetic gear with the finite element method

The gears have been seen in almost every area of daily life; speed change, torque transmission, directional change etc. are physical constructs that perform applications. In this respect, the use of gears are very important. Speed and torque magnitudes to raise or lower the required values are indispensible for the gears. These physical structures, which can be seen in various industrial applications, especially in vehicles, wind power plants, clock mechanisms, are suffering greatly from negativities such as overloading, heating, friction and fatigue of the material. Periodic maintenance against overload and excessive heat, lubrication, etc. protective measures are taken. However, the continuity of these measures brings with it costs. Mechanical fatigue, mechanical friction, overload, heating etc. the absence of problems caused the magnetic gears to be on the agenda. In recent years, the concept of magnetic gear has attracted both industry and research centers, and this interest has recently gained momentum. Through the use of magazines, articles, patents and conferences, it is possible for the academy to keep the magnetic gears of the industry on the agenda. However, the torque in the magnetic gears is limited to a certain upper value. The torque limit value means that there is a maximum torque value that the gear can reach. If the torque value of the gear exceeds the torque limit value, the gear wheel will slip. In applications, it is ensured that the torque limit value is not exceeded by taking the necessary precautions to prevent this problem from appearing. The maintenance of the torque value is also very important for the protection of the physical system. The situation encountered here can be described as a disadvantage that can be seen in magnetic gear. Although the advantages of the concept of magnetic gear have a prescription in everyday life, they have not seen the necessary interest in academia or industry in the early days when this concept emerged. The reasons for this include the complexity of the system and the lack of sufficient features of the first samples of permanent magnets. In the early examples of this mechanism, in which the gear were placed in the poles, electromagnetic properties were seen to be obtained from permanent magnets towards the middle of the twentieth century, and development with every published patent became clear. NdFeB and SmCo in the permanent magnet class are the type of magnet in which the rare earth elements are placed. Other permanent magnets are Ferrite and Alnico which are widely used in the market. In the first part of this thesis study, general usage areas of mechanical gears are briefly introduced and the disadvantages encountered in daily life are listed. In some applications, the use of direct drive systems and the introduction of magnetic gear have been passed, emphasizing the efficiency of this system. As a result of the absence of mechanical contact with the magnetic gear, some disadvantages encountered in the mechanical gear are not seen. However, the low torque intensity can be described as a disadvantage encountered in such structures. In this section, the development of the magnetic gear from past to present, the investigations made and the results obtained are introduced in the scope of the literature study. In the second part, gear types used in everyday life are described; together with their structural characteristics, advantages and disadvantages. In the third chapter, the concepts of magnetism and magnetic materials are given. Influence of temperature on magnetic materials is emphasized in brief under the concept of Curie temperature. At the same time, rare earth elements and their use in everyday life are listed in tabular form. In the fourth chapter, the method of finite element which is used to realize torque analysis in magnetic gears is mentioned. Analytical method takes time for solution and this method is applied for solution of difficult problems. COMSOL Multiphysics 5.3 and FEMM 4.2 were used in this thesis study of the programs which are operated with the principle of finite element method. In the fifth section, COMSOL and FEMM programs are briefly introduced. Instructions for running programs are described both in figures and in diagrams. In the sixth part, torque analyzes of magnetic gear in different parameters are performed by using COMSOL and FEMM programs. The analysis results obtained from both programs are graphed and each output is interpreted. Torque graphs of gears at different inner and outer rotor speeds are obtained for static and dynamic situations. In this context, the effect of the gear tooth thickness on the torque value and torque efficiency is examined. This section also includes some formulations regarding the use of superconductivity in the gear mechanism. Differences were investigated by placing the bulk superconducting samples in the stator of the magnetic gear instead of the air gap in the stator of the classical magnetic gear. In this case, fluctuations in the related graph despite the increase in momentum are also observed. The work done for the magnetic gear so far, which have many positive aspects, is not sufficient. Nevertheless, parallel to the development of technology, the theoretical and practical studies to be done on the magnetic gear will be improved and the results will be positive in terms of efficiency of torque and torque intensity; it will also open up better and more efficient designs. Safety factors play an important role in both mechanical and magnetic gear. It can be predicted that magnetic gear is useful compared to the mechanical gear in terms of efficiency, torque and force capacity, safety and mechanical properties are taken into account and it is predicted that magnetic gears may take place instead of mechanical gears in the future. Hybrid vehicles, wind power plants, aerospace, automotive industry, etc. every field where gear can be used will show itself and contribute to humanity. However, the fact that the cost of production costs and the cost of rare earth elements are high prevents the spread of magnetic gear in today's market. On the other hand, with the development of technology, it is expected that cost values decrease and magnetic gear become more widespread on this matter. As a result, the literature on magnetic gear shows that the working conditions for industrial applications are sufficient. In this thesis, a specific magnetic gear configuration is investigated by means of the finite element method widely used for electromagnetic analysis. The use of superconducting material in magnetic gear has also been discussed with the evaluation of different geometries. Finally, the structure of the magnetic gear in which the superconducting material is placed in the stator; it is believed that the stator is different from the magnetic gear structure with air gap, but experimental studies are needed to investigate this difference in more detail. Experimental studies are recommended after this thesis work and it is expected that practical work advantages and disadvantages will be revealed as a result of these studies.