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by Miles
Aug 19 2019 4:18pm
Forum: General Discussion
Topic: Go Cedric!
Replies: 14
Views: 601

Re: Go Cedric!

Some background for those not up to speed....:



by Miles
Jul 29 2018 1:31pm
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 5496

Re: Minimising rotor losses

You're on a roll, Lars :) Thanks for the useful references. Interesting how little the resistance between surfaces needs to be to avoid conduction of eddys.... I guess that's why you can get away with a thin oxide layer on stator laminations. With regard to finding the likelihood of serious rotor lo...
by Miles
Jul 29 2018 4:40am
Forum: E-Bike Build Threads / Photos & Video
Topic: My Sun Trip Bike, Back to Back Tandem Trike with Rowing Generator, Pedals, +Solar
Replies: 334
Views: 37682

Re: My Sun Trip Bike, Back to Back Tandem Trike with Rowing Generator, Pedals, +Solar

Awesome adventure Justin! Thanks for sharing the experience, all the way from conception.

Can't wait to see your hybrid rowing boat! Rowing generator; pedals; batteries; solar panelled roof/sail; propellor............ 8)
by Miles
Jul 27 2018 2:35am
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 5496

Re: Minimising eddy currents in rotor

Topic split at the point where the discussion of eddy currents in the rotor starts. Let me know if it needs any further attention...
by Miles
Jul 21 2018 3:43am
Forum: Motor Technology
Topic: Minimising rotor losses
Replies: 94
Views: 5496

Re: Revolt RV-series motor review and comparisons

Furthermore, I just posted what my friend in the UK has told me several times. That electrical conductivity is not the issue. He just told me that NOT having gaps between the magnets is creating the heating and losses in the magnets in higher RPM motors. Which I just posted here earlier today. He m...
by Miles
Mar 28 2018 7:38am
Forum: Motor Technology
Topic: Astro 3220 Rewind
Replies: 3
Views: 658

Re: Astro 3220 Rewind

Hi Cole,

It's 8P 24T which is an integer-slot winding.
Best to wind it as a single layer winding to get a winding factor of 1. That means the coil will span 3 slots.
See here for more information: https://www.emetor.com/windings/
by Miles
Mar 21 2018 7:30am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Everything needs to be balanced. There has to be enough iron in the teeth to avoid saturation etc.

There's no ideal distance. It varies a bit depending on the scale of the motor. For our uses around 0.6mm to 1.4mm. Obviously, the shorter the distance the greater the flux for a given magnet.
by Miles
Mar 21 2018 2:39am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Ok so the end TURN if not contributing to the Pole flux at all or at least significantly can be kept short by having more slots/teeth closer together in the core thus increasing the number of stator slots thus increasing the number aka total active length of the windings increasing the motor torque...
by Miles
Mar 19 2018 5:57am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

I further suspect that even though the full turn of the coil does not contribute to the Lorentz calculation that this does NOT mean it has no effect, this is merely a side effect of that particular analytical approach to the solution. Both the permanent magnet field, and the coil field exist in the...
by Miles
Mar 19 2018 5:20am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Ok now for the end turns...I mean the wire between the coils around a stator tooth ... The entire length of the end turn is ... The circumference of the stator core ... No, that's not what we're discussing in this thread. It's the section of each turn of the coil returning it to the other side of t...
by Miles
Mar 18 2018 3:45pm
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Buk___ wrote:
Mar 18 2018 3:29pm
Look around their site, and see if you can find them referring to their motors as BLDCs. They certainly don't fit most descriptions.
https://www.thingap.com/industries/
by Miles
Mar 18 2018 1:57pm
Forum: Motor Technology
Topic: Magnetic reaction force and magnet strength
Replies: 8
Views: 781

Re: Magnetic reaction force and magnet strength

Brushless Permanent Magnet Motor Design - Duane C. Hanselman But start with the first chapter of: Electric Motors and Drives - Austin Hughes https://books.google.co.uk/books?id=jjuTYtKokc8C&printsec=frontcover&dq=fundamentals+austin+hughes&hl=en&sa=X&ved=0ahUKEwjlyNaWhZ_LAhVHthoKHaAuDtIQ6AEIJjAA#v=o...
by Miles
Mar 18 2018 11:26am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

In the interest of balance: http://www.mpoweruk.com/machines.htm
by Miles
Mar 18 2018 10:38am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

by Miles
Mar 18 2018 9:13am
Forum: Motor Technology
Topic: Magnetic reaction force and magnet strength
Replies: 8
Views: 781

Re: Magnetic reaction force and magnet strength

Surely, the limiting factors for torque are core saturation and heat dissipation?

The reason I posted the link to that post is that thinking of the situation as two opposing magnets is intuitive but misleading, as that thread shows...
by Miles
Mar 18 2018 5:47am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Buk___ wrote:
Mar 18 2018 5:28am
The only thing that can explain such belligerent denial of the obvious is faith. I cannot argue with faith; which is why it has no place in science.
:shock:


https://www.edge.org/conversation/paul_ ... e-on-faith
by Miles
Mar 18 2018 4:36am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Electric Motors and Drives - Austin Hughes - Chapter1, Page 18 (My emphasis in bold). The final question relates to the similarity between the set-up shown in Figure 1.10 and the Field patterns produced for example by the electromagnets used to lift car bodies in a scrap yard. From what we know of ...
by Miles
Mar 15 2018 2:48pm
Forum: E-Bike General Discussion
Topic: The ebike parts designing thread with CAD/CAM
Replies: 128
Views: 13260

Re: The ebike parts designing thread with CAD/CAM

Alan B wrote:
Mar 08 2018 3:54pm
No, these:

https://www.3dconnexion.com/products/spacemouse.html

Looks like they use it in addition to a mouse.
I've been using one since they first came out, in the 1990's. Wouldn't be without it......
by Miles
Mar 15 2018 9:26am
Forum: Motor Technology
Topic: End turns bad?
Replies: 246
Views: 15571

Re: End turns bad?

Hanselmann 1.jpg
Hanselmann 1.jpg (37.32 KiB) Viewed 1412 times
This is from Hanselmann "Brushless Permanent Magnet Motor Design" page 209
"Motor constant as given by (9.11) ignores the winding end turns. Since the end turns create ohmic losses but do not produce torque, they directly diminish motor constant."