Research Of Thermal And Electromagnetic Optimization Design On Air-core Power Reactors With Paralleled Cylindrical Coils

The key property of power reactors are their inductance and current carrying ability. The optimization designs of large air-core power reactors focus on the contradiction between the key property of reactors and their cost of production. This thesis focuses on the optimization design of air-core power reactors from thermal and electromagnetic perspectives.The thermal optimization is the principal methods of design optimization of air-core power reactors, thus the thermal characteristics of air-core power reactors with cylindrical coils are researched in chapter2. Temperature field computed with the finite element method (FEM) are given. By analyzing the results, it gives the regular pattern of temperature field and the heat dissipation process of air-core reactors. Refer to the mentioned analysis results and the correlational research by other researchers, the author of this thesis developed the temperature field computation method based on similarity theory and experimental correlations of heat transfer theory. The new method is the theoretical basis of the thermal optimization theory developed in this thesis.In chapter3, a "unit height, unit heat flux" theory about the heat load distribution theory between the paralleled coils is put forward. According to the heat dissipation theory, the paralleled coils have the same heat flow on the surface, and the same heat dissipation ability in the vertical air ducts. Thus it guarantees the paralleled coils have the same temperature field and almost the same use ratio of the metal conductors.An optimization theory named heat transfer efficiency of the "coil-air duct" unit is also put forward in chapter3. By adjusting aspect of the "coil-air duct" unit, the heat source distribution, the velocity and fluid flow states of the air in the vertical duct are adjusted. A reasonable adjust can improve the heat dissipation ability of the "coil-air duct". Hence, the current carrying ability of the metal conductors in the coils can be improved while keeping the maximum temperature of the coil unchanged. In chapter3, the optimize curves are given and the heat transfer efficiency coefficient are defined according to the heat transfer coefficient efficiency theory. The heat transfer efficiency of the "coil-air duct" unit provides a new direction for thermal optimization of the air-core power reactors.In order to improve the effects of the flux crosslinking among the wire turn, in chapter4 the electromagnetic optimization theory of air-core coils are studied. According to the essence of the electromagnetic efficiency of the air-core coil, a reasonable formula is chosen to reconstruct form the "Huck figure" which reflects the electromagnetic of thick coils. The "Huck figure" is proved effective in the electromagnetic efficiency of power reactors. However, the "Huck figure" hasn’t considered the thermal condition while adjusting the aspect of the overall coils; hence it can’t be used directly in the optimization of air-core power reactors.The thermal-electromagnetic combined optimization theory based on the mentioned three theories is considered in chapter4. The mentioned three optimization theories are considered as equality constraints as: unit height constraints, unit heat flux constraints, fixed maximum temperature rise constraints, fixed inductance constraints. By constructing the structure function, the relationship between the dosage of the metal conductors and the aspect ratio of the overall coil of the air-core power reactor is obtained, which is defined as the "thermal-electromagnetic coupling optimization theory". As a result, Optimization curves of air-core reactors are formed, according to which the best aspect ratio of the air-core reactors is redefined. The combinatorial optimization theory considered the thermogenesis, heat transfer process, the electromagnetic property; it will bring a new and better method of the reactors’optimization design.Chapter6introduces the programming realization process of the design optimization theories introduced in this thesis. After that, some design cases of air-core power reactors are given to prove the veracity and utility of the optimization theories mentioned in the former chapters. The optimization of a new kind of air-core reactor named High Coupled Split Reactor (HCSR) and the iron core reactor are introduced in chapter5. The results prove that the optimization theories can be applied in many kinds of power instruments with coils.