- #1
jrive
- 58
- 1
edit: The key thing I am after is why the ferrite might be responsible for the increase in resistance I measure on the coil.
Hello,
i have a coil designed to be 2.2mH and54 ohms. When an MN60 ferrite (T-ish core) is used with it, the inductance rises to 6.1mH as expected, and the resistance remains the same up to about 10kHz. Above 10kHz it begins to rise, and at the desired operating frequency, it rises to 8Kohms! (measured with LRC meter). The resistance of the coil by itself (without the ferrite) rises slightly, but is still below 100ohms at 220kHz.
So, we surmised the issue has to do with the losses in the ferrite, but we cannot pinpoint exactly what. We simulated this in Flux 3D, including the ferrite per the material datasheet, and the simulation does show a rise in ac resistance (not reactance) due to proximity effect as expected, but it is only a hundred ohms or so (clearly, we modeled some o the parameters but not the "right" one to demonstrate the behavior we see with the real part).
Does anyone have any experience with this that can shed some light as to what may be happening? Or can explain some basics physics of ferrite materials and how the losses manifest themselves (is this what I'm seeing?).
Also, I just started looking into the Loss Factor, since I noticed from the datasheet that it goes up significantly for this material at 300Khz (it goes from 12 at 100kHz to 55 at 300kHz), but I am having trouble understanding what this really means. Any help here is also appreciated..
Thank you
Jorge
Hello,
i have a coil designed to be 2.2mH and54 ohms. When an MN60 ferrite (T-ish core) is used with it, the inductance rises to 6.1mH as expected, and the resistance remains the same up to about 10kHz. Above 10kHz it begins to rise, and at the desired operating frequency, it rises to 8Kohms! (measured with LRC meter). The resistance of the coil by itself (without the ferrite) rises slightly, but is still below 100ohms at 220kHz.
So, we surmised the issue has to do with the losses in the ferrite, but we cannot pinpoint exactly what. We simulated this in Flux 3D, including the ferrite per the material datasheet, and the simulation does show a rise in ac resistance (not reactance) due to proximity effect as expected, but it is only a hundred ohms or so (clearly, we modeled some o the parameters but not the "right" one to demonstrate the behavior we see with the real part).
Does anyone have any experience with this that can shed some light as to what may be happening? Or can explain some basics physics of ferrite materials and how the losses manifest themselves (is this what I'm seeing?).
Also, I just started looking into the Loss Factor, since I noticed from the datasheet that it goes up significantly for this material at 300Khz (it goes from 12 at 100kHz to 55 at 300kHz), but I am having trouble understanding what this really means. Any help here is also appreciated..
Thank you
Jorge
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