Toroidal inductors are widely used in modern electronic equipment due to their closed magnetic circuit, high efficiency, low leakage flux, and strong anti-interference capabilities. Their main applications include: input/output filtering inductors, energy storage inductors, and PFC inductors in switching power supplies; and power inductors in DC-DC converters (such as Buck and Boost topologies). For higher power applications, to prevent magnetic saturation, the toroidal inductor often requires an air gap or uses a distributed air gap iron powder core. They are also used in high-power switching-mode power supplies, high-power LED ballasts, and power line filters.
Inserting a toroidal inductor in series with power and signal lines, along with a capacitor, forms an LC filter, effectively suppressing common-mode and differential-mode conducted interference. Nickel-zinc ferrite inductors, which have good high-frequency characteristics, are commonly used. Their toroidal topology helps maintain low electromagnetic interference/radio frequency interference.
In conjunction with a capacitor, they form an LC resonant circuit for use in oscillators, frequency selection networks, and tuning circuits. They are also used as impedance matching and tuning elements in radio frequency circuits.
They are used in pulse and energy storage applications requiring the storage and release of magnetic energy. In the field of sensing, toroidal coils (magnetic coils) can be embedded under the road surface to form an oscillating circuit with capacitors. Vehicles cause changes in inductance, which are then converted into changes in the resonant frequency, thus enabling traffic flow detection.
Toroidal coil inductors (especially iron powder core toroidal inductors) are the most commonly used type of power inductor, widely used in computer motherboards, computer power supplies, power supplies, mobile phone chargers, lighting transformers and dimmers, uninterruptible power supplies (UPS), and various home appliance control boards. Despite their very small size, toroidal coil inductors are still used in large quantities, primarily in high-frequency, high-inductance communication products.
