I am looking for a motor that can give me 40 watts at 400 rpm. So like 1 N-m of torque at 400 rpm, with fair efficiency. All the brushless motors in the price range that makes sense are like 3000 rpm at 24 volts, no load, optimal commutation.
So I am thinking : is it possible to just use finer gauge wire and more windings in the stator??? Or would the magnetic material of the stator or rotor become saturated and things wouldn’t work very well? Or something?
This gimbal motor is what I’ve been using, it can do this 40 watts at 400 rpm no problem but it’s just way too expensive. https://jdpowershop.com/?product=jd-power-dch-6829f-flat-dc-hollow-shaft-brushless-motor-with-hall-sensor
These are the most promising class of motors I have been looking at, they are commonly used in CNC spindles for instance:
In general, you cannot change the rated torque of a motor by changing the windings. But you do change the KV-value by the thickness of the copper wires and the number of windings. The rated torque will in general be proportional to the volume of what is inside all the outer magnets.
In speed ranges below 1000 rpm and not that high shaft power, you may find stepper motors more attractive. Perhaps some of the BLDC motors for skate boards might be closer to what you need too. This is one of them (but with not so mush data):
https://vi.aliexpress.com/item/1005006548045544.html
I am sure this motor cannot withstand 2900 W continuously. But at peak power it manage 4 Nm.
One thought would be to change the magnets to a higher strength magnets.
You are trying to generate force. This may also result in cogging… increasing your diameter or stack length would be the preferred method of torque generation… past that, gearing the system down is preferable.
There is mention above of skate board motors. Trampa has some nice motor + herringbone gear offerings.