Analysis And Research On The Electromagnetic Properties Of Superconducting Electrical Machines

Compared with other types of energy,electric energy has the advantages of usability,no pollution,and long-distance transmission which is the most important type of energy supply and consumption.However,with people's consciousness of environment protection increasing,the gradual electrification upgrade,and the further development of new energy,a general trend of high power density,high efficiency and low loss in electrical equipment and electric energy consumption is upwards.Except optimizing the structure of electrical equipment,the applications of various new materials in electric devices are an important research object.Utilizations of new materials not only improve the performance of electrical equipment,but also promote the development of corresponded industries,of which superconducting materials are most remarkable.Superconducting cables and superconducting magnets are employed in the electrical machines in most cases.With the continuous advancements of superconducting theories and superconducting processing techniques,a variety of new superconducting cable structures are emerging,and that for the requirement of actual engineering,the optimized design of various superconducting cables and superconducting magnets has also been successively put forward.However,the published superconducting literatures focus on the microscopic structure generally,making the explanation of the physical mechanism of superconducting phenomena and improving their processing technologies.The overall performances of the superconducting equipment are only discussed without considering the detailed superconducting components.The above-mentioned description shows that these literatures do not focus on the superconducting applications rather mostly concentrate on superconducting physics neglecting the superconducting macroscopic electromagnetic properties,and there does not exist a superconducting unified modeling theory and computational model in the perspectives of practical application.For the new structures of superconducting cable,research direction focuses on improving the mechanical properties of these new structure ignoring electromagnetic analysis.There is a lack of comprehensive considerations in the research and development of superconducting machine taking the multi-physics coupling of electromagnetic and thermal fields into account.Thanks to the specific requirements of superconducting materials currently on electrical equipment promotion,this dissertation mainly studies superconducting wires,superconducting magnetization loss,superconducting magnets,superconducting synchronous motors,superconducting eddy current actuators,and superconducting magnetic gears from superconducting physical mechanism and Maxwell equation set.The mathematical model of macroscopic electromagnetic phenomena,electromagnetic field,temperature field and other related models have been studied in terms of superconducting magnetization loss and superconducting machine temperature field distribution.The electromagnetic equations of superconducting electricity are studied via the superconducting microscopic theory based on physical principle and the superconducting macroscopic model based on test results and the superconducting numerical calculation model based on Maxwell's equations.The analytical model of magnetization loss has been put forward for the single-core of TSTC and CORC in the varying magnetic field.At the same time,superconducting numerical calculation formula based on the H electromagnetic equations is built to calculate the magnetization value of TSTC cable and CORC cable in time-varying magnetic field;the main procedure of superconducting low temperature environment construction process and superconducting magnetic performances test are briefly described and analyzed;the development,measurement and analysis of MgB₂ superconducting wire and MgB₂ race-track superconducting magnet production,electromagnetic test and analysis are discussed.According to the multi-physics design and analysis,the electromagnetic field and temperature field have been studied on MgB₂ superconducting synchronous machine to obtain the temperature distribution;Based on the thermal field theories and equivalent principles,the equivalent thermal network model has been proposed and studied comparatively;Based on the principle of superconducting bulk magnet,eddy current drive technology,and equivalent magnetic circuit principle,the axial superconducting eddy current actuator has been proposed and studied comparatively.Based on the combination of superconducting bulk magnet,magnetic gear theory,and subdomain model of electromagnetic field,axial superconducting magnetic gear has been proposed and studied comparatively.