Brushless motor and voltage characteristics

Question

In order to choose a small motor for a size constrained design, I have been looking at Faulhaber https://www.faulhaber.com/fr/produits/series/3216bxtr/ motors.

They always offer different models with different nominal voltages but the other characteristics remain more or less the same (dimensions, speed and torque), except for the current that is inversely proportional to the voltage (so the same power as well).

Since they are one of the only manufacturer found that offer such an option, I was wondering : How are they able to do so?

I assume that each model have different winding with a different number of turns and wire diameter (or that magnets are changed for each model) but it's just an hypothesis... If anybody could satisfy my curiosity I would be delighted!

Thanks in advance!

Answer 1

They simply wind the motor according to a range of projected requirements.

All other manufacturers will do the same, on request, accompanied by a large enough order. They just won't all make the full range available off the shelf.

(But some do : RC car suppliers sometimes offer "extreme" or "nitro" versions of the same motor by reducing the turns per winding, to increase the speed constant KV, which also tends to increase the operating current (by reducing the torque constant Kt).

If you can dismantle a motor without damaging it, you can unwind its stator (BLDC) or rotor (brushed), count the turns, and re-wind it to better suit your purpose. With some motors, if the winding space is not full, you can improve efficiency a little, by adding more turns or moving to a larger wire gauge and filling the winding space with more copper.

If you like, consider it as half transformer, half gearbox, where the input is electrical and the output is mechanical, and you can control the input voltage and current, and the output speed and torque, by adjusting the turns count.