Answered: Voltage vs Torque


Assuming that one uses a power supply able to feed infinite current (to take current out of the conversation) to the 1st generation motors we are all using today; would that power supply’s output voltage affect the motors’ rotation speeds (RPMs)?

I can imagine that the motor package might contain circuitry that attempts to keep the motor speeds constant (by regulating the voltage the actual motor sees) or they could let speeds rise and fall as (battery) voltage rises and falls.

If it does make a difference (no voltage-limiting circuitry), do you have some graphs or other data describing how that speed will vary in the unloaded-motor situation and for a few different loaded-motor situations?

Finally, if the microcontroller to motor path doesn’t contain any voltage regulation now, are you (will you) considering adding that for the future? I can see it being a big benefit for competition teams. They would be able to get more predictable/repeatable autonomous and teleop performance from their bots without having to sink an inordinate amount of their budget into an attempt to start each use with one of several identically charged batteries. Hobbyists would probably enjoy the more predictable performance (repeatable motion) also.

PS: Yes, I realize that the title is slightly off-target; but I can’t edit the title now…

**Yes, if the control signal is held constant and the supply voltage is varied, the rpm’s of the motor will vary.

Unfortunately we do not have information on varying voltage with respect to varies loaded motors. You should do some testing and create your own feedback loop based on battery voltage and the varying motor speed from your specific design.

Unfortunately there are no plans for a constant voltage for the motors. **

Ricky - Thanks for confirming the behavior. - Blake