Maximizing Copper Fill

[hias9]

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?

[markz]

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]

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.

[markz]

There was a discussion on 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

[ekline309]

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]

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 (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.

[Chalo]

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.

[larsb]

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.