Discussion on Materials for Common Mode Inductors 1

Let's start with the magnetic ring type:

Core material: primarily nanocrystalline; wire material: this will not be discussed;

Advantages of the iron core:

High initial permeability (a fundamental requirement for common-mode inductors), high saturation magnetic flux density, relatively stable temperature performance compared to ferrites (understood as low temperature rise), flexible frequency characteristics, and the ability to achieve large inductance with minimal material due to high permeability, offering a wide operating frequency range;  diode

Overall advantages:

Since the initial permeability is 5-20 times that of ferrite, its suppression effect on conductive interference is far greater than that of ferrite;

The high saturation magnetic induction of nanocrystalline materials is superior to that of ferrites, making them less prone to saturation under high currents;

The temperature rise is lower compared to the UF series. In my actual tests, it was approximately 10 degrees lower at room temperature (personal test values are for reference only);

The structural flexibility ensures excellent adaptability, allowing it to meet diverse requirements by modifying the manufacturing process (e.g., the flexible application of magnetic rings in energy-saving lamps);

The distributed capacitance will be smaller, as the winding area is wider and the volume is relatively smaller;  diode

The loop uses fewer turns and has smaller distribution parameters, resulting in higher efficiency (specific analysis is required; I suspect it's due to the wire diameter, and further details would be helpful);

Overall disadvantage:

The small aperture of the magnetic ring makes it difficult for machines to thread, requiring manual winding, which is time-consuming and labor-intensive, resulting in high processing costs and low efficiency. As cost pressures continue to rise, this issue has become particularly critical.

In terms of voltage resistance, the advantage over UF is not significant: I came up with this idea because I noticed many common-mode chokes separated by zip ties, which seems unreliable. Some have a certain distance between them, with wires fixed by potting. How reliable is this over time? If high inductance is required, the wires may bunch together, raising some safety concerns.diode