Inductors, akin to conductors and resistors, are basic components utilized in electronic devices to perform specific tasks. Typically, inductors are coil-like structures present in electronic circuits. These coils consist of insulated wire wound around a central core.
Inductors are primarily employed to reduce or regulate electrical surges by temporarily storing energy in an electromagnetic field and then releasing it back into the circuit.
What Is an Inductor?
An inductor is a passive component found in most power electronic circuits, used to store energy in the form of magnetic energy when electricity is applied. A key property of an inductor is its opposition to any change in the current flowing through it. When the current across the inductor changes, it either gains or loses charge to balance the current passing through it. Inductors are also known as chokes, reactors, or simply coils.
An inductor is characterized by its inductance, which is the ratio of voltage to the rate of change of current. Inductance is a consequence of the induced magnetic field in the coil and is influenced by factors such as the coil's shape, number of turns and layers of wire, spacing between turns, permeability of the core material, and core size. The SI unit of inductance is the henry (H), equivalent to weber/ampere, denoted by the symbol L.
Furthermore, an inductor differs entirely from a capacitor, which stores energy as electrical energy. An inductor stores energy in the form of magnetic energy and changes its polarity while discharging, allowing the polarity during discharge to be opposite to that during charging.
Construction of an Inductor
An inductor typically comprises a coil of conducting material, often insulated copper wire, wound around a core made of plastic or ferromagnetic material. Ferromagnetic cores with high permeability help increase and confine the magnetic field, resulting in higher inductance. Inductors for low frequencies are constructed like transformers, with laminated electrical steel cores to prevent eddy currents, while those for higher frequencies often use 'soft' ferrites.
Inductors come in various shapes and types, including those with adjustable cores for changing inductance and ferrite bead inductors for blocking high frequencies.
Planar inductors feature planar cores, while small-value inductors are integrated into circuits using interconnect processes, typically with aluminum interconnects formed in a spiral coil pattern. However, small dimensions limit inductance.
Shielded inductors, commonly used in power regulation and lighting systems, are often partially or fully shielded for low-noise operation.
Different Types of Inductors
Inductors are classified based on the materials used:
Iron Core Inductor
Air Core Inductor
Iron Powder Inductor
Ferrite Core Inductor, further divided into Soft Ferrite and Hard Ferrite. Iron Core Inductors, made with iron cores, are compact with high power and inductance but limited high-frequency capacity, suitable for audio equipment.
Air Core Inductors, lacking a core, are used when low inductance is required, resulting in high-quality factor due to increased turns.
Ceramic inductors are often referred to as air-core inductors.
