Electromagnet Design

[travin69]

Hello all.  Looking to get some design advice and brainstorming on my electromagnet design.  Here are the "facts" I have based my design on.  If I have come to some wrong conclusion, I would appreciate someone correcting me.  My electromagnet is 24 volts dc.  Looking to stay under 1 ampere total current draw.  Duty cycle is around 50%. 

The Facts:

The strength of an electromagnet is directly proportional to its pole area and exponentially proportional to its magnetic flux.  The method to get more magnetic flux is to either run more current (via higher voltage or less resistance) OR more windings.  Since I want more flux with same current, I want more windings.  I want to use smaller wire to get more windings.  Smaller wire takes up less area per turn so I can get more windings in the same volume.  The problem is more windings of smaller wire means more resistance, ie, less power.  So to combat this problem I want to use multiple windings of smaller wire connected electrically in a parallel arrangement.  This should allow me to add more windings of smaller wire while still maintaining equal resistance.  This should also lower the coil inductance and allow faster current rise during the on cycle.

Also, thought about using flat wire vice round wire.

What do you all think about this?

Thanks,

Daniel

[avalon]

I think you are on the right track in general.

A while back I was looking into the same. I found that apart from the points that you have mentioned, the quality (and the type of) winding is very important too. In my case I ended up winding the coil using litz wire, making sure that after finishing one layer the wire was brought back to the beginning in a straight line and then another layer was wound and so on.

Electromagnets with coils produced as described above had better holding power than the others I had. Since I was satisfied with the end result I had never done quantitative comparison of different coils.

[Xaverius]

Sounds like you've done your homework, Daniel.  I came up with the same concept a few years ago.  Using a higher guage wire connected in parallel would give you increased magnetic field strength from more windings but the same amount of power consumption.  Also I have never used flat or square wire but it might be a good idea as far as winding is concerned.  It would make your turns neater and more efficient.  Good luck with it.