--- In MEG_builders@yahoogroups.com
, "Rob King" <k1ngrs@...> wrote:
> Posting here instead, long live Yahoo!
> Hi Paul,
> I just ran your silmulation and noticed the input coils as being
> round in shape, surely these will be rectangular and tighter to the
> core than shown.
> I do not think you will get the 100 turns in the small circle.
> Also you have set the depth to 0.75 inches, this should be 50mm (2
> I do not understand why the second input coil is set as air?
> I would have thought it best to create a second current circuit and
> assign it to this but as a coil.
> Sorry for picking holes in your sim.
> Next step is to create a material like the Metglass, that means
> entering an BH curve.
Rob, nobody has any idea what you are talking about, so lets at least
tell them. I gave Rob a FEMM simulation of Naudin's MEGv21. Rob is
asking why I made the actuator coils so small.
Rob, it is fine to extend the coils, but it will make very little
difference. If we understand how closed loop cores react to magnetic
fields we know that the wire locations make very little difference
unless you are talking about very high frequencies. Also it is the
magnetic field from the wire that enters the core that makes nearly
all the difference. FEMM simulation is DC current on a closed loop
core, so extending the coils will only make a slight difference.
The reason I used Iron instead of creating a Metglas property is for
1. The permeability of Metglas is not 600000 at 30 KHz. More like ~10000.
2. It takes a lot of time and it was a quick job; i.e., I'm spending
far too much time on such things when I should be working on the
The only way you could make the FEMM more accurate than mine is if you
create a metglas property for the core and k-factor the coil current
way down to adjust for the fact that the cores permeability
drastically changes at 30 KHz. Also extending the actuator coil will
help a tiny smidgen.