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How to reduce the electromagnetic interference of the iron-silicon-aluminum magnetic ring inductor?
Jul 17, 2018


How to reduce the electromagnetic interference of the iron-silicon-aluminum magnetic ring inductor?


The composition of the ferrosilicon powder core contains 85% iron (Fe), 9% silicon (Si), and 6% aluminum alloy powder (Al), which has the advantages of high energy storage, high saturation magnetic flux density and stable performance at high temperatures. . Ideal for power factor correction circuits, it is a low loss and relatively high saturation material. However, there is a certain skill in winding iron-silicon-aluminum magnetic ring inductors, otherwise electromagnetic interference is easily generated. This kind of electromagnetic interference comes from stray capacitance, mainly from two aspects, one is the capacitance between the windings, and the other is the capacitance between the winding and the core. The reduction of electromagnetic interference can be started from these two aspects. The turn-to-turn capacitance is related to the winding method and the number of turns of the coil, and the capacitance between the winding and the core is related to the core material. Minke Xiaobian summed up the six techniques for solving the electromagnetic interference of iron-silicon-aluminum magnetic ring inductors:


1. Increase the distance between the winding and the core

If the core is a conductor, a layer of insulating material having a lower dielectric constant is added between the winding and the core to increase the distance between the winding and the core.

2, try to single layer winding

When space permits, try to use a larger core, so that the coil can be a single layer, effectively reducing the interturn capacitance;

3, multi-layer winding method

The number of turns of the coil is large, and when it is necessary to be wound in multiple layers, it is necessary to wrap in one direction, and overlap the sides, and do not wrap around one layer, and then wrap it around;

4, segmented winding

The coil is segmented on a magnetic core such that the capacitance of each segment is small, and the total parasitic capacitance is a series connection of parasitic capacitances on the two segments, the total capacity being smaller than the parasitic capacitance of each segment;

5, multiple inductors are connected in series

A large inductor can be decomposed into a large inductor and a small number of inductors with different inductances. By connecting these inductors in series, the bandwidth of the inductor can be expanded.

6, input and output are far away

Regardless of the form of inductor, the input and output of the coil should be kept away, otherwise the capacitance between the input and output will short the entire inductor.



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