Years ago I did a little project starting out using stepper motors. During its development I played with increasing the terminal speed, how fast could I get the motor spinning.
Slow rotation on load and the amount of load or it's inertia, the important factor, was easy. Trying to start and run beyond a fairly repeatable speed barrier resulted in failure. The motor rotor would just buzz instead of rotated. Ramping the speed up from very/too slow would solve this and I would easily break the pervious speed limit.
Then I got a bit greedy. How fast could I ramp up to? Provided I ramped up the speed the stepper motor reached way beyond what I needed but there was a problem. On approaching the limit speed simply tapping the motor shaft would stall it. As the speed increased the torque dropped because the inductance of the motor coils would not allow the current through to generate the necessary torque output. Clever driver circuit design and higher voltages can mitigate this but it's best avoided.
My project ended up ditching stepper motors because the variable loads and the need for accurate positioning took me to using precision DC motors with quadrature shaft encoders and a closed loop control system.
Slow rotation on load and the amount of load or it's inertia, the important factor, was easy. Trying to start and run beyond a fairly repeatable speed barrier resulted in failure. The motor rotor would just buzz instead of rotated. Ramping the speed up from very/too slow would solve this and I would easily break the pervious speed limit.
Then I got a bit greedy. How fast could I ramp up to? Provided I ramped up the speed the stepper motor reached way beyond what I needed but there was a problem. On approaching the limit speed simply tapping the motor shaft would stall it. As the speed increased the torque dropped because the inductance of the motor coils would not allow the current through to generate the necessary torque output. Clever driver circuit design and higher voltages can mitigate this but it's best avoided.
My project ended up ditching stepper motors because the variable loads and the need for accurate positioning took me to using precision DC motors with quadrature shaft encoders and a closed loop control system.
Statistics: Posted by RaspISteve — Sat Aug 09, 2025 10:36 am