3 phase Common Mode Choke


I need to design a 3phase CM choke with inductance of 3.5mH.

The fundamental and ripple frequencies are 50Hz and 400Hz. The rated and peak current would be 9 and 13.5A respectively.

Which core should i choose? Either nano crystalline or ferrite core? .

Please provide your suggestions..

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michwolf says:


Generally, the main points that determine when I choose one material or another, are the operation frequency in which the design must work, the maximum available space and the budget.

Although ferrite cores would do well on these specifications, nanocrystalline materials present a much higher permeability which allows, at a given frequency, to reach the required impedance with a smaller number of turns, implying then, fewer losses and temperature.

However, nanocrystalline cores are quite expensive. For a given size, nanocrystalline cores will perform better than ferrite, but having a price from 4 to 5 times higher.

At the end it depends on the size and cost requirements. If you have enough space, you could go for a ferrite core which would be far cheaper. However, if you are looking for an optimum performance you could then go with the nanocrystalline core which will allow to minimize turns and copper loss.

By looking at your specs, It would be right to use a ferrite type core. Ferrite components are characteristic for it`s low eddy currents and low losses at high frequencies. And, despite the fact that a nanocrystalline core could fit pretty well, these are quite expensive. It depends on your preferences.

Published: 7 months ago