lamination thickness

[sfyten]

I am working on the design of an electromagnet that uses silicon iron laminations. I am looking for a formula or chart that will help me determine what the thickness of the laminations should be. The electromagnet will operate at 0-400 hz.

 

[UKpete]

I have never seen a specific formula that you can use, however lamination suppliers do supply design tables giving the watts loss per kg (or lb in the US) for a given peak flux density, usually 1.5T (15kg) and frequency.

An example :

http://www.orb.gb.com/

(if you select "brochures" from the products menu, then download the most appropriate brochure, e.g. Non-oriented, fully processed and look on page 25, the table shows the watts/kg at 400Hz for a range of flux densities). If you are in the US, there is a brochure for ASTM grades.

If you know your working flux density (note PEAK values are always used, not RMS) and the total mass of steel, you can calculate the total loss. This assumes the flux density is uniform throughout the core and it is sinusoidal.

In an electromagnet it may be possible to use oriented steel provided the flux is always in the preferred direction in all parts of the core, this is more expensive but has significantly lower loss.

You will need to design for the worst case (i.e. 400Hz), probably needing a 0.35mm grade or equivalent.

 

[IRstuff]

This is cross-posted from thread248-115214

TTFN

 

[UKpete]

thanks IRstuff, I think I'll repost this in the other thread.