mxlemming
100 kW
- Joined
- Jul 17, 2020
- Messages
- 1,125
So after completely failing to get Neumotors to sell me a motor (I really can't see what is so damned hard about 8038, 70kV, extended shaft version preferably with a keyway... any keyway will do...) and being 21 emails deep with Lisa Talia and still zero progress... I think I might try building a motor. I've kind of wanted to for a while.
Thing is, I don't really know much about this, so far I have done loads of controller related stuff, and have basically taken the little 8080 BLDCs and a 1500W hub as they come. This might be the motor learning thread for me.
I think the ideal motor for my ebike would probably be ~50kV, spins up to about 4krpm @20s battery (so with a ~7:1 reduction and 26" wheels I would get about 40mph) and weigh sub 2kg.
So thinking I would start with something like this (if they are really 2$ each I will find a hat to eat):
https://www.alibaba.com/product-detail/HIGH-Quality-Silicon-Steel-Brushless-Motor_1600116087634.html?spm=a2700.12243863.0.0.38403e5fEroHx8
Hopefully I can just get this completely off the shelf and stack them 2 high for 40mm of lamination
And wind it like this:
using something like 0.7mm wire 10 strands of, no idea how many turns... that's a calc for another day...
Seems like 22 and 26 pole motors use the same winding. Presumably 26 spins slower and has more torque.
So if I did this, with a 100mm air gap, 3mm or 5mm magnets 10mm wide * 40mm long (314mm circumference/26 = 12mm, 314/22 = 14.27mm which sounds about right for a motor magnet spacing), then in the 64mm hole in the middle shove a big old pair of 12mm bore bearing (6001 series 12*28*8?) and a lump of aluminium full of holes to force air through for cooling.
Total motor would be about 1.4kg plus the weight of the copper, which I guess would be significant, maybe 0.5kg?
Knocked this up in about half an hour in Solidworks. My day job is doing solidworks, so really doesn't take long.
Adding a plausible amount of copper to it gives about 2.1 kg.
Worth trying for? Am I missing anything obvious?
Thing is, I don't really know much about this, so far I have done loads of controller related stuff, and have basically taken the little 8080 BLDCs and a 1500W hub as they come. This might be the motor learning thread for me.
I think the ideal motor for my ebike would probably be ~50kV, spins up to about 4krpm @20s battery (so with a ~7:1 reduction and 26" wheels I would get about 40mph) and weigh sub 2kg.
So thinking I would start with something like this (if they are really 2$ each I will find a hat to eat):
https://www.alibaba.com/product-detail/HIGH-Quality-Silicon-Steel-Brushless-Motor_1600116087634.html?spm=a2700.12243863.0.0.38403e5fEroHx8
Hopefully I can just get this completely off the shelf and stack them 2 high for 40mm of lamination
And wind it like this:
using something like 0.7mm wire 10 strands of, no idea how many turns... that's a calc for another day...
Seems like 22 and 26 pole motors use the same winding. Presumably 26 spins slower and has more torque.
So if I did this, with a 100mm air gap, 3mm or 5mm magnets 10mm wide * 40mm long (314mm circumference/26 = 12mm, 314/22 = 14.27mm which sounds about right for a motor magnet spacing), then in the 64mm hole in the middle shove a big old pair of 12mm bore bearing (6001 series 12*28*8?) and a lump of aluminium full of holes to force air through for cooling.
Total motor would be about 1.4kg plus the weight of the copper, which I guess would be significant, maybe 0.5kg?
Knocked this up in about half an hour in Solidworks. My day job is doing solidworks, so really doesn't take long.
Adding a plausible amount of copper to it gives about 2.1 kg.
Worth trying for? Am I missing anything obvious?