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Andoni Garcia

Steinmetz Core Losses

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Hi everyone,

 

I´m simulating the magnetic behaviour in a varying frequency on some cores but I've got a restriction.

I have understood that, if I want to simulate a core in a certain frequency to get core losses,  I would have to introduce the B(H) curve in the material expecifications (for the same frequency).

I use to fill the "Isotropic Spline Saturation" gaps with "Sine wave magnetic field", adding the 6 Modified Bertotti losses coefficients.

 

But what if I got B(H) information for only 1Hz - 10kHz range? How can I calcule the losses for 150kHz?

Is there any way to draw upon of Steinmetz or another technique in FLUX?

 

Thanks

 

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Hi Andoni,

You are right, if you want to get a simulation as accurate as possible you should use the B(H) curve corresponding with your working frequency. This will affect not only your iron losses but also the global accuracy of your simulation.

At the best of my knowledge, it is difficult to estimate B(H) curve at 150 kHz when you only have information for a much lower range. I am sorry but I cannot help with this part.

Anyway, the good new is Bertotti model already considers the effect of frequency, as you can see in the formulation of Bertotti’s equation used in Flux:

image.png

It is worthwhile to notice that Bertotti’s coefficients are taken as frequency independent. This approach usually works well, except when you reach elevate values of frequency.

Best regards,

Alejandro

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On 2/28/2020 at 12:28 PM, Alejandro Rodríguez said:

Hi Andoni,

 

 

You are right, if you want to get a simulation as accurate as possible you should use the B(H) curve corresponding with your working frequency. This will affect not only your iron losses but also the global accuracy of your simulation.

 

 

At the best of my knowledge, it is difficult to estimate B(H) curve at 150 kHz when you only have information for a much lower range. I am sorry but I cannot help with this part.

 

 

Anyway, the good new is Bertotti model already considers the effect of frequency, as you can see in the formulation of Bertotti’s equation used in Flux:

 

 

 

 

image.png

 

It is worthwhile to notice that Bertotti’s coefficients are taken as frequency independent. This approach usually works well, except when you reach elevate values of frequency.

 

 

Best regards,

 

 

Alejandro

 

 

 

Thanks for your kind answer Alejandro.

 

I've been working just on that with the Modified Bertotti model:

I took one core and I calculed experimentally the iron losses on 50Hz & 1kHz.

Afterwards, with those values I obtained the Modified Bertotti modified for each frequencies.

 

The issue is that, if you draw the real B(P) curve (1kHz) against Modif Bertotti f parameters obtained in 50Hz curve using for 1kHz, the fuction deviates 14% from the real values. So althought it seems to be the most viable option, it wouldn't be a precise solution.

 

image.thumb.png.aab0a7066747d4cb7391f558ac71b43f.png

 

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Hi Andoni,

I fully agree with you. It is really complicated to obtain accurate values for a given frequency when your losses have been measured at another different frequency, errors as high as 14% can be expected.

Actually, we have another remark in the forum about this kind of effects (in this case, the problem was about local spatial effects that may change losses in particular areas of the device, even if the material does not change: Lamination Punching Edges & Packaging: Investigation / Consideration).

Unfortunately, I cannot propose you a better alternative. This subject stills a field of study with more questions than answers.

Best regards,

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