Quote
uhrheber
Did anybody ever thought of adding capacitors at the motor voltage inputs of the driver modules?
The capacitors that are already on the boards look very small to me, and I bet that they aren't low ESR types.
The more steps per revolution you make, the higher the pulse frequency gets, and the higher the losses in the capacitors will be.
Not only will the aluminium capacitors degrade faster because of that, they'll also not be able to deliver that much pulce current, resulting in reduced torque and step losses.
When switching from 16 microsteps to 128, you should use way bigger capacitors, with low ESR, and put big ceramic capacitors in parallel. You should even put additional capacitors on the stepper module itself, as the PCB traces and connectors have significant resistances and inductances.
The microstepping makes no difference to the losses in the capacitors, because the drivers are chopping the motor current (normally at an ultrasonic frequency) all the time anyway. At high motor speeds, the effective microstepping rate will be much lower than programmed, because the theoretical microstepping rate will be higher than the chopping frequency.