03.26.2022
How to choose inductors and what are the types of inductors?
Inductors have many uses in electronic circuits, so there are many types. The following is a brief description of how inductors are selected.
Common Mode Inductors
Common mode inductors are used for common mode filtering in electronic circuits and are mainly divided into ferrite common mode inductors and amorphous common mode inductors.
Ferrite common-mode inductors are characterized by good high frequency filtering characteristics, with the disadvantage of large size and poor temperature stability.
Amorphous common-mode inductors are characterized by their small size, low winding number, good temperature stability, and poor high-frequency attenuation characteristics.
The design of common-mode inductors is based on two main considerations.
1 Select the cross-sectional area of the copper wire to prevent it from heating up too much.
2. Choose the right size of Core to facilitate the winding of copper wire.
Differential Mode Inductors
When selecting a differential mode inductor, the situation is more complex and is influenced by two factors: magnetic saturation and temperature rise.
The design requires that the inductor not be saturated and that the temperature rise be reasonable.
The saturation of the inductor is mainly governed by the saturation flux density of the core material, while the temperature rise is related to the choice of copper wire thickness and core loss characteristics.
Under sine wave AC, the differential mode inductance is calculated as
U=4.44NBSF
U=2*IπFL=XL*I
XL inductance
U Voltage
N Number of turns of winding
B Magnetic induction strength
S Cross-sectional area of iron core
F Frequency
I Current
L Amount of inductance
According to the formula, it can be seen that the most critical design of the inductor is to select the right B value. For different materials, the Bs value determines the upper limit of the selected B value. If high frequency currents are present, the Bs value is much lower than the Bs value, considering the presence of Core Loss.
Foresee New Material's iron-silicon series inductors have a Bs value of 1.6T and low high frequency losses, making them a good choice for use as differential mode inductors, filter inductors, BOOST inductors, and PFC inductors. The high Bs value provides the conditions for miniaturization of the product, while the low high frequency loss makes the inductor perform better in high frequency conditions.
