What is an inductor, its purpose, and how does it work? Inductors are an electrical component made essentially of a coil of wire, often wound around a magnetic core. From our experts, here are some facts to help you better understand this technology.
What is the Purpose of an Inductor?
The purpose of inductors are that they store energy in the form of a magnetic field. This is a very useful property for applications such as switching power supplies. Also due to the close proximity of the turns within an inductor, each turn’s induced magnetic field acts to “push” and slow the induction of another. This means inductors act to “choke” or slow changes in the current through it. The “slowing” force is frequency-dependent and the greatest choking action happens on high-frequency noise and transient currents.
There are many different types of inductors:
- Toroidal Inductors
- Bobbin Core Inductors
- Air Core Coil Inductors
- SMD Power Inductors
- Power Factor Corrector (PFC) Inductors
There are three variables that determine the size of an inductor: number of turns (also called windings), size of the cross-sectional area of the windings, and core material. Inductance increases proportionally with the cross-sectional area of the windings and the magnetic permeability of the core material, and proportionally with the square of the number of turns. The magnetic permeability of the core can range from 1 (for air) to >20,000 for special core materials.
How is a Magnetic Field Created around an Inductor?
When current flows through a wire, a small magnetic field is formed around it. If there are many coils or high current, the strength of the magnetic field increases. Energy will be stored in the magnetic field. The magnetic field, in turn, exerts a force that opposes the current flow. It is the work done in moving the current by a source of voltage, pushing against the opposing magnetic fields that try and slow/stop it, that is the energy stored by the inductor.
When the current stops flowing, the magnetic field will begin to collapse. The magnetic energy that has been stored breaks back across the turns of wire forcing a flow of current. It is now the conversion of magnetic energy back to electrical energy. The currents within and magnetic fields surrounding an inductor do not grow, peak, decay or cease instantaneously. How quickly these occur are a direct function of the applied voltage and the inductance itself.
What is the standard unit of measurement for inductance?
The standard unit of measurement is the “Henry”. Practical inductance values range from a few nanoHenries (nH) to several Henries (H.)