by LROBBINS » 03 Dec 2020, 15:48
Lack of starting torque on the gearless/brushless motors won't be cured by a controller change though sinusoidal commutation and field oriented control might help some (but Dynamic controllers already have sinusoidal commutation). When I was searching for motors for the current project chair I set specs for RPM, starting and running torque and asked for quotes for both (geared) brushless and brushed motors. The brushless offerings, even with gearing, consistently had much lower starting torque than brushed motors with similar running torque - in fact none would have been adequate. Will has found brushless motors that do give enough starting torque, so this might not be intrinsic to brushless motors just of the motor bids I got from my RFQ. It is certainly the case, however, that finding brushless motors, even geared ones, that aren't marginal for starting torque seems to be a difficult proposition.