Recent content by hillma

Thanks Miles, thought I needed to keep below 1T so that is excellent news - no extra magnets required (though I was surprised by the impact the additional magnets made to the flux intensity in the back iron but happy to save the £40ish !) Hopefully the build will start this weekend! Cheers Mark

Okay, last try with FEMM this evening. Having resolved the un-even flux distribution in V4 I was seeing a high level of saturation in the iron rotors, peaking above 1.3T (if I'm reading the scale correctly?) with .6 or .7T in the airgap. After playing around with inserting 5x5x25mm magnets...

For this motor I'm going for a slotless back to back winding (Gramme's winding wired up as AcBaCb repeated 8 times for 48 coils, 16 per phase) on a single laminated stator with outer rotors either side...thought it best to refine this before moving onto multiple stator designs :D or maybe...

Many thanks for that suggestion- I've reduced the width of the outer magnets by half and the flux distribution is now behaving as expected :D :D :D in the attached v4 FEMM Now all I need to do is sort out this rotor back iron saturation and I should be there! Cheers Mark

With the attachment !! :lol: :lol: :lol:

Now that I've settled on the wedge magnets I've discovered an unexpected consequence of reducing the gap between magnets from 10mm to 5mm. In the attached FEMM image the bottom rotor shows every other pole saturating the rotor iron which is very odd, if I open the gap back to 10mm the flux...

About time for a bit of an update :D After re-reading tons of online information and much scratching of head I've settled on the following revised spec. So far magnets, wire, steel and acrylic have all been ordered and should start turning up this week ! (Unfortunately as Jersey is a smallish...

At a guess very efficient active cooling of the stator to allow for the high current and halbach array to minimise rotor weight would be my 2cents. Cheers Mark

Thanks Major :lol: :lol: :lol: :lol: !! Though I think the large clip on the end might interfere with the end windings ? I have been searching around and have come across these guys who also happen to be on my side of the pond, they seem happy to deal in small quantities and I'm waiting to...

Thanks Miles, I hadn't considered the aluminium being a factor....you mentioned the operating frequency of 100 Hz, at the risk of a dumb question how do you arrive at that number and at what value would the frequency become an issue? Cheers Mark

Hi Miles, many thanks for posting up the great CAD drawings (I'm still at the pen and paper stage!), that's exactly what I have in mind :D . For my first attempt I might stick to the 12 magnet layout for ease of construction and treat it as a learning exercise though the 24 magnet approach does...

Hi Ian, thanks for your reply. I've re-run FEMM with additional magnets (changed to N40 - thanks Miles) as suggested and the results show a more even distribution of flux to the adjoining magnets and avoiding saturation as per my previous effort 8) Cheers Mark

Hi Miles, First attempt at modelling in FEMM. I've replaced N50 with N42 magnets which have kept levels below saturation...... just!. I've not yet included the coils as part of the circuit and a guess this will have a impact on results, need to work on this later today. Any comments and...

Hi Miles Many thanks for your response - I'll have a go at modelling the stator in FEMM which I've just found, much to learn :D. When I have something that's representative of the stator I'll post up the results for any feedback. I've not been able to find much reference on ES to the Torus...