Ferrite for Wireless Power Transfer

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Firenze02

Joined Sep 1, 2018
34
Hi,
I'm working on a wireless power transfer project (operating frequency 100 kHz). As you probably know, ferrite is usually placed under the coil to create a low reluctance way and reduce the leakage flux.

How the coecive force Hc and the residual magnetic flux Br affect the hysteresis losse?

For example, in the attached file you can find different ferrite types with different Hc and Br.

What is the logical reasoning with which I should choose a soft ferrite with high Hc and low Br or viceversa?

Thank You.
 

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ian field

Joined Oct 27, 2012
6,543
Hi,
I'm working on a wireless power transfer project (operating frequency 100 kHz). As you probably know, ferrite is usually placed under the coil to create a low reluctance way and reduce the leakage flux.

How the coecive force Hc and the residual magnetic flux Br affect the hysteresis losse?

For example, in the attached file you can find different ferrite types with different Hc and Br.

What is the logical reasoning with which I should choose a soft ferrite with high Hc and low Br or viceversa?

Thank You.
A ferrite core concentrates the lines of magnetic flux - whether you need to do that depends on the physical dimensions involved. All the proximity charged toothbrushes I've hacked had air cored pick up coils - but probably some form of core in the charging base.

Types and grades of ferrite are specified for frequency ranges - none of them are much good under a few tens of kHz.
 
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