Maximizing Copper Fill

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hias9   100 W

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Maximizing Copper Fill

Post by hias9 » Dec 27 2020 7:25pm

Hub motor stators usually have a piece of wood and paper on top of each stator slot.
Is this additional insulation or too keep the copper windings where there are?

Would it be a good idea to remove these pieces and add maybe 1-2 strands of winding wire to increase copper fill?

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markz   100 GW

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Re: Maximizing Copper Fill

Post by markz » Dec 27 2020 9:28pm

Slot liner insulation protects the winding conductors during insertion into the stator slots.

The slot liner insulation also provides additional insulation between the motor winding wires and the stator laminations.

The slot liner insulation also provides extra insulation at the sharp edge where the motor windings exit from the motor stator slots.

Phase to phase insulation can also be used to add additional insulation where large voltage gradients are present between adjacent windings.

larsb   10 MW

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Re: Maximizing Copper Fill

Post by larsb » Dec 29 2020 7:36am

you'll find that those extra wires don't give a large increase in fill if it's not a (really) crappy motor winding.

The other thing is that the windings closest to the magnets are more affected by eddy losses. I’ve seen some tests where it wasn't worth it to pack the final layer closest to the slot opening as the lower resistance was offset by the increased eddy losses.

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markz   100 GW

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Re: Maximizing Copper Fill

Post by markz » Dec 29 2020 6:56pm

There was a discussion on :es: about if you could make a square wire if that would be beneficial.

Could be this one, search term "fill square" 10 pages worth
3 posts with "square" in same one
viewtopic.php?f=30&t=102934&p=1505953&h ... e#p1505953

Read the quote
viewtopic.php?f=31&t=65031&p=1197760&hi ... l#p1197760

Iron Fill
viewtopic.php?f=30&t=90037&p=1445084&hi ... l#p1445084

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ekline309   10 W

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Re: Maximizing Copper Fill

Post by ekline309 » Jan 05 2021 10:37pm

Square wire is great in theory but in my experience it is a huge pain, especially when you are moving from one layer to the next. This is the best article I've ever found about maximizing copper fill: https://ieeexplore.ieee.org/document/651289

larsb   10 MW

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Re: Maximizing Copper Fill

Post by larsb » Jan 06 2021 12:30am

I’ve done some square wire winds, it’s really dependent on the way you shape the wire. This is a 60% winding.
F5428A80-C891-4365-9FAF-5BCA42ABB9B2.jpeg
F5428A80-C891-4365-9FAF-5BCA42ABB9B2.jpeg (121.03 KiB) Viewed 122 times
From there it’s hard to get a large increase in fill whatever method is used. 90% or whatever is mentioned in the paper won’t ever be wound on a motor coil.

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Chalo   100 GW

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Re: Maximizing Copper Fill

Post by Chalo » Jan 06 2021 12:42am

Makes me wonder where there's anything in using hexagonal wire. It would at least be able to pack in more densely, like square wire but easier to work with.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

larsb   10 MW

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Re: Maximizing Copper Fill

Post by larsb » Jan 06 2021 2:52am

I don’t find square wires to be that difficult but it’s true they cannot be wound as quickly as a softer/lower diameter multiwire wind. The thicker wires have the benefit of being bulletproof in comparison to the super thin wires on many chinese rc motors.

Anything less than a true 30% is a poor winding and anything above 60% is remarkable in my book.

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