Powerful Knowledge 10 - Finite element modelling of magnetic components

[@HereisAnatolii]

Thank you very much! Been waiting for this topic

[@ElectronicmindsUK]

Are there other areas you would find interesting?

[@pfrillele]

Hello,do you know which material in the library should be used for METGLAS Alloy 2605SA1?Thank you.

[@ElectronicmindsUK]

I’m sorry but I don’t know. I believe you can define your own materials though from the underlying magnetic properties. Good luck!

[@pfrillele]

@@ElectronicmindsUK I am just wondering why it is not included in the Library,i thought it is allready a common material.Thanks for the fast answer.

[@idk2412]

Really great video, such a great initial kicker into FEMM! But is it just me or is the video of you clicking through FEMM so laggy that you don't actually see a lot of where you are clicking? It's weird though cause your voice is smooth and continuous, it's just watching you go through FEMM..

[@ElectronicmindsUK]

I'll take a look at the video for you. If it is laggy like you say then I'll check the settings on how it was recorded as it maybe too compressed perhaps.

[@marlowe7604]

@ElectronicmindsUK how did you model the actual winding?

[@ElectronicmindsUK]

We found that you can model in two main ways in FEMM, either define a composite area which you then specify a number of turns to contain or draw them individually. Mostly the composite approach works well enough.

[@hallkbrdz]

Any way to model flux transfer of a permanent magnet with FEMM? This is in reference to the memory effect when a coil steers the flux to one path or the other where it remains after the coil is de-energized. Also, how do I describe laminates with this 2.5D (x,y and an overal z) model?

[@ElectronicmindsUK]

Good question! I've not modelled permanent magnets myself with FEMM but there are some examples online of people doing this. Take a look at www.femm.info/wiki/PermanentMagnetExample. There are some other guides which cover modelling laminates in FEMM, take a look at www.femm.info/wiki/onedge

[@AidanWaltonwires3]

Thanks for the nod towards FEMM and your tutorial efforts. I have been looking for opensource FEA, and this seems a good start. Having said this, in trying to apply the tool to an existing personal project I straight away hit some issues. Firstly I note that you have used an E core from TDK, this has a 'planar' symmetry. This I assume is most suitable for a 2D tool like FEMM. I have been running my LTSpice simulations for my LLC converter using a TDK ETD core. This has a sort of truncated axisymmetric shape. Have you specifically avoided such ferrite shapes. If not any tips about how to model them. If I choose an axisymmetric problem then the depth option is greyed out. Presumably the defined plane is spun around a vertical axis. But I would then have a shape which is nothing like an ETD core. I assume this is a basic limitation of a 2D tool such as FEMM?

[@ElectronicmindsUK]

Hi Aidan, thanks for your detailed comments. Great to see you have been playing with FEMM, especially since you are modelling an LLC. this is a great topology and we are building one at the moment too. Watch out for deltaB in your magnetics, we have found that the dominant loss mechanism in our the converter is core loss. For the ETD, I can see the problem you have in that the centre leg is round in cross-section which does make it rather hard to model in a 2D tool. I've not looked into trying to model these style cores and i think you correct that 2D tools such as FEMM will struggle. Maybe you could approximate the centre leg by modifying it to be a square cross-section instead with the same x-sectional area? This should give a reasonably good approximation but depends how detailed you want your modelling to be (fringing etc will not be correct). To do this accurately you probably need a 3D tool such as Comsol but I've not had any experience myself with that. Still, as a free tool, you can do a lot with 2D FEMM.

[@AidanWaltonwires3]

Thanks Ian, It seems we came to the same conclusion. I either try and approximate the centre leg by adapting its width to more effectively represent the cross-sectional area, or I stick with using a square section core. I have built a couple of LLCs already at lower power levels ~200W and hand-calculated and iterated. This time however I am aiming at >1kW and it is starting to look like I need to model closer to reality as things are likely to get both expensive and hot if I get it wrong. However thanks for your helpful comments.

[@powerconversionlimited4013]

First! 😁 Great video!

[@ElectronicmindsUK]

Nice!

[@umeshksoni]

sir what you done for entering the coordinates at starting. which key was pressed?

[@ElectronicmindsUK]

Here is the user manual link, it’s all covered in there www.femm.info/Archives/doc/manual42.pdf

[@Noob_Engineering]

Tab key