Research on electromagnetic efficiency optimization in the design of air-core coils

Abstract

Summary In this paper, the electromagnetic efficiency factor is defined to describe the utilization rate of metal conductors in air‐core coils. The geometry‐electromagnetic character and the thermal condition of the coil are coupled to describe the electromagnetic efficiency of the air‐core coils. The geometry‐electromagnetic character is deduced form the inductance computation formula, while the thermal functions are given according to the “Uniformed electrical current density condition” and the “uniformed temperature rise” condition. Curves that reflect the electromagnetic efficiency factor are given while the thermal condition is considered as the mentioned two conditions. The former thermal condition is simpler and is proved to be suitable for midget air‐core coils without complex heat transfer structure or coils with pulse current. While, the latter is proved to be with higher accuracy and can be wildly used in the optimization design of air‐core power reactors. Copyright © 2014 John Wiley & Sons, Ltd.

Thermal optimization for nature convection cooling performance of air core reactor with the rain cover

“…Thus, combined with the average fluid temperature rise calculation method in Ref. , the maximum temperature rise Δ T max of the encapsulation can be written as , where the first term is the average fluid temperature rise, and second term is the fluid–solid temperature difference: The average fluid velocity u in air ducts can be calculated according to : where μ is the dynamic viscosity of the fluid in air ducts.…”

“…In order to realize the same temperature rise and not more than the limit after adding the rain cover, the temperature rise calculation methods in the inner encapsulations are essential. Table I, if the heat and heat dissipation conditions of the inner encapsulations are basically same, it could realize the same temperature distribution of each encapsulation, so the "encapsulation-air ducts unit" can be taken as the study object to reflect the temperature rise of the reactor [23,24]. Considering that the diameter of the encapsulation is larger than the width of the air ducts for a large air-core reactor, the unit can be considered equivalent to the vertical tube tank model, as shown in Fig.…”

“…Thus, combined with the average fluid temperature rise calculation method in Ref. [24], the maximum temperature rise T max of the encapsulation can be written as (13), where the first term is the average fluid temperature rise, and second term is the fluid-solid temperature difference:…”

Research of electromagnetic and thermal optimization design on air core reactor

“…In Refs , the design method combined with thermal and electromagnetic optimization is proposed, to realize the minimum use of the metal conductor, but the encapsulation number is not considered, which directly affects the electromagnetic efficiency and thermal efficiency of the reactor and limits the optimization results. Thus, the encapsulation number should be taken into account in the optimization design of the reactor.…”

Thermal and Electromagnetic Combined Optimization Design of Dry Type Air Core Reactor

“…In [14,15], the thermal and electromagnetic optimization are combined in the design of the reactor, however, the change of the air duct width and encapsulation number are not simultaneously considered, which directly affects the electromagnetic and thermal characteristics of the reactor, and eventually lead to the results that the design parameters not being optimal. Thus, the air duct width and encapsulation number should be taken into account.…”