Variable inductor is an inductor with a saturable magnet core, which belongs to the category of inductors. The magnet core has three iron core columns (42, 43, 44), including a central iron core column (43) and two outer iron core columns.
Inductors are components that can convert electrical energy into magnetic energy and store it. The structure of inductor is similar to that of transformer, but there is only one winding. The inductor has a certain inductance, which only blocks the change of current. If the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is connected; If the inductor is in a state of current flow, it will try to maintain the current when the circuit is disconnected. Inductor is also called choke, reactor and dynamic reactor.
The inductor is generally composed of skeleton, winding, shielding cover, packaging material, magnetic core or iron core, etc. Inductors include two categories, self inductors and mutual inductors.
When there is current flowing through the coil, a magnetic field will be generated around the coil. When the current in the coil changes, the magnetic field around it also changes correspondingly. The changed magnetic field can make the coil generate induced electromotive force (induced electromotive force) (electromotive force is used to represent the terminal voltage of the ideal power supply of the active element), which is self induction.
Inductance can be made of conductive material coiled around the magnetic core, typically copper wire, or the magnetic core can be removed or replaced with ferromagnetic material. The core material with higher permeability than air can restrict the magnetic field more closely around the inductive element, thus increasing the inductance.
In terms of the structure of the variable inductor, the induction coefficient of the coil on the outer core column changes with the current passing through the control coil. The saturation of the outer core is changed by controlling the current of the coil. In one embodiment, the induction coefficient of the control coil remains basically constant with the change of the current in the control coil.