Abstract
Air-Core Reactors are deceptively challenging devices to design and model, and are often used in shunt configurations for transmission line compensation or current limiting applications in switching.The reactor is constructed by winding conductors in cylindrical layers without a ferrous core, and connecting the layers in parallel to minimize overall device resistance.
The total inductance of an air-core reactor is largely due to the mutual coupling through the linear core media, air, which also has the effect of linking the current from one layer with that of another linked layer.
Managing the current distribution in the design phase is a critical aspect to achieve the desired rated inductance, and to mitigate the losses through heat generated by the conductor resistance.
Balancing the mutual coupling and resistance to control the distribution of current in the reactor layers is a significant challenge in the design process stemming from the high mutual coupling of the layers.
An issue presents as a "reversed" real component of a layer when sufficiently more current is contributed to a layer through the mutual than what is coming from the terminals of the layer winding.
This reversed current, sometimes called a circulating current, resulting in a higher net resistance and heat generation when in use.
The works here propose to directly control the leakage flux, that is, the flux that only links to the same current, by adjusting the mutual coupling through direct manipulation of the windings physical displacement relative to the rest of the reactor.
By directly controlling the leakage flux, and the related leakage inductance, the method presented is suitable to fine-tune a reactor design to further improve the efficiency of the final reactor.
In addition to the methods to directly control leakage inductance, there is a presentation of general air-core reactor design principals and the underlying theory.
As air-core reactors are simply wire wound around a cylindrical form, there is a demonstration of the design tools and methods applied to design a small-scale model reactor.
The small-scale unit is then physically constructed and parameters measured to demonstrate and verify the theory and methodology presented.
The goal of these works is to adequately present a methodology for design and optimization, currently lacking in published literature.
The application of which would result in more efficient air-core reactors designed, produced, and utilized in power transmission infrastructure.