A truly versatile component, inductors are used across many industries to create impedance, modulate current flow, store energy, or some combination thereof.
When current is introduced into their windings, inductors effectively resist changes in that current: When current increases, an inductor will stabilize it by turning the excess current into a magnetic field; when current decreases, energy stored in the magnetic field is converted back into the current and then added to the decreasing current to bolster it.
Core Materials and Shapes
An inductor’s core shape and material can be customized in many ways to meet specific circuit type and power requirements. Both shape and material can greatly impact an inductor’s properties, as well as the applications for which it can be used.
Inductance, energy loss and energy storage, and the overall stability of these properties in various environmental scenarios are all dictated by material type. Common core materials include silicon steel, iron, and nickel; also ferrite, powdered versions of these core materials, and no core at all (“air cores”). The choice depends on the specific customer requirements.
Inductor shapes — “C” cores, toroids, stamped laminations, and a variety of unique ferrite shapes — also affect an inductor’s properties and performance, so having a clear understanding of your specific needs is imperative to ensure efficiency and reliability.
Common mode inductors are used to impede noise that is common to both power leads in high-frequency applications. Toroidal common mode inductors are extremely effective in switched-mode circuit noise or EMI reduction applications. Differential mode inductors are used in applications with currents that cannot be canceled by an opposing current (as is the case with most common mode inductors). Toroidal inductors are also ideal for both minimum volume and weight high-performance scenarios although other core shapes can be used to better fit the mechanical requirements.
No matter how narrow your application, inductors can be designed and customized to meet your specific needs.
Considerations for Inductor Design
To ensure optimal performance and longevity, three important factors should be taken into account when designing an inductor — core material, wire and winding, and packaging.
Inductor materials must effectively meet an application’s unique circuit requirements; while some materials can store large amounts of energy at DC or low frequencies, for instance, they will exhibit high losses at high frequencies. Regardless of the rest of the design, an inductor with an ill-suited core will not perform to its potential.
Wire and winding — how the wire is wound around the core — are the most important considerations during the design stage, as they affect every measurable inductor property. Wire material, size, and shape, as well as winding frequency and pattern, should all be carefully chosen. The winding design determines the coil losses.
Finally, packaging must also be considered — not the materials an inductor is shipped in, but rather the material in which it is sealed. Environmental factors are usually the most pressing concern here; for optimal protection, inductors must be properly hermetically sealed or encapsulated (or even encased in metal, depending on the application). Mechanical stresses (“shock and vibration”) as well as ambient temperatures, humidity, and reliability all determine the best package.
With over 70 years of experience, Triad Magnetics is proud to be an industry-leading manufacturer of magnetics and electronic components, including a wide array of inductors. As part of our commitment to quality and customer satisfaction, we believe it’s important to share educational resources and our industry knowledge. To learn more about inductors and important design considerations to keep in mind, download our free comprehensive eBook, “Guide to Inductors: Basics of Inductors.”