Hilden-Brand Magnet Motor

[MeggerMan]

I am currently looking at simulations for a 40 x 40 x 12mm ferrite transformer core. Two "E" shapes.
With a 5mm yoke and outer limb width, 12mm diameter centre limb.
The results are as follows:

40mm Core                  

Mag Dia   Current   Field   Off   Field   Diff   No Mag
2   0.05   0.105   0   0.051   0.054   
3   0.05   0.16   0   0.085   0.075   
4   0.05   0.21   0   0.11   0.1   
4.5   0.05   0.24   0   0.14   0.1   
4.7   0.05   0.25   0   0.15   0.1   
5   0.05   0.27   0   0.17   0.1   
5.5   0.05   0.32   0   0.22   0.1   
6   0.05   0.39   0   0.3   0.09   
5   0.04   0.25   0   0.17   0.08   0.017
5   0.05   0.27   0   0.17   0.1   0.02
5   0.06   0.3   0   0.17   0.13   0.026
5   0.07   0.32   0   0.17   0.15   
5   0.08   0.34   0   0.17   0.17   
5   0.09   0.37   0   0.17   0.2   


Mag Dia in mm, centre limb diameter is 12mm.
The current is in amps
Field in Teslas for the outer limb.
Off current is in amps (no current in input coil)
The no magnet column is where I replace the magnet with steel.
I cannot find ferrite as a material in FEMM so I used silicon steel.

The important column is the "difference". This is the difference in Teslas between the on state of 50mA and off state of zero amps.

I will post the images later so that you can see clearer what I am talking about.

Regards

Rob

[MeggerMan]

Hi,
The largest core half I can find is this one from Ferroxcube:
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3056430&N=401

Uses 3C90 core material. Anyone know how/where to get the parameters for ferrite (B/H curves)  into Femm material library?

Around 59 x 62 x 22mm

The ferrite will give a higher flux density for a given coil/current than silicon steel but has a lower saturation as a result.
As I understand it it also does not suffer so much with eddy currents.
I read on one site the typical saturation for ferrite is about 400mT which is fine for what I want.

I plan to drill a hole into the centre rod of the "E" (both halves) to house the neodymium magnets (10 off N38 5mm x 3mm disks).
Then grind a small cutout in the leg part of the "E" to take the hall effect sensor.
The two halves will sandwich the sensor in the slot.
Then I can test various currents in the input coil (centre leg/limb) and measure the flux density in the outer leg.
I plan to test this with the core I currently have (39mm x 45 x 12mm).

Then the next part it to use a square pulse from a NE555 timer to drive the input coil, add two extra output coils to the outer legs and measure the flux with various output loads.
At the same time I can take measurements of power and plot a graph of input power and output power vs frequency.
Hopefully at some point output will exceed input. ;o)

Regards

Rob

[MeggerMan]

Hi,
See attached femm file for:

Simulations for a 40mm sq. "E" core, 12mm thick:






5mA for on current giving 272mT in the outer limbs
0mA for off current giving 78mT in the outer limbs.

Notice I put an air gap in between the two sets of magnets, I needed to do this to keep the flux density low for the off state and within the saturation of the ferrite in the on state.

Regards

Rob

[gyulasun]

Hi,
The largest core half I can find is this one from Ferroxcube:
http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3056430&N=401

Uses 3C90 core material. Anyone know how/where to get the parameters for ferrite (B/H curves)  into Femm material library?

Hi Rob,

Here is a link to a Data Sheet of the 3C90 material and the B/H curves are included. But I do not know how to enter these data into FEMM library (because I haven't used the software yet...)

Gyula

[MeggerMan]

And that link is where?