Basic Concepts of Inductor Design

We introduce some of common iron core materials and their characteristics to guide engineers in design reference.

Inductor is a kind of magnetic induction element which according the required number of turns to use insulated cooper wire to wind on bobbin or core as a coil.

According to the principle of electromagnetic induction, when DC voltage and current pass through the coil, a magnetic field will be generated; or when AC voltage and current pass through the coil, an alternating magnetic field will be generated; and the induced voltage will be generated to resist the change of the original magnetic field. 

This characteristic of resisting the change of current is called inductance.

Formula of inductance value: 
L is inductance.
N is number of turns in coil.
μ is magnetic permeability.
Ae is cross-sectional area of equivalent magnetic circuit.
le is the length of equivalent magnetic circuit.

There are many types of inductors, which are closely related to the winding method, the number of turns, the magnetic material of the iron core, the insulation level of the copper wire, and the operating temperature.

The core shapes of inductors include toroidal core, EE core, EI core, drum core, RM core, Pot core, cut core, UU core…etc.   

The iron core materials include ceramic core, ferrite powder Mz / Zn, Ne / Zn and iron powder…etc., it is stamped according to different characteristics and then sintered at high temperature.   

The winding methods include wire wound, multi-layer, molded; and the coils include with shielded, non-shielded and core shielded.

Without considering resistance, the inductor can pass through DC current, and has high impedance to AC current. During the demand of circuit, it has the functions of choke, filter, turning, energy storage…etc.   

In the application of switch power supply, inductor is the most important of energy storage. It is combined with capacitor to form a low-pass filter, which can reduce the output voltage ripple value. Therefore, it is an indispensable element in filtering.

If you want to know more about the design application, please feel free to contact us.