Hi VESC forum,
I've ordered a small VESC EDU to experiment a bit with some motion control applications on the VESC. I have a bit of a background in motion control, so I'm curious about the potential of this platform. In experimenting I've come accros some strange glitches, which I can't really explain. So I was wondering if anyone else has an idea what I might be doing wrong :), or maybe someone can replicate the same behaviour?
Issue
It seems like there are some short glitches in the measured current. The figure below illustrates the issue, it's a plot of the measured current while the setpoint is (steady) at 1A:
Conditions
- This is with a "freshly tuned" motor (FOC)
- Feedback: ABI Encoder, also freshly "detected"
- The motor runs smoothly in Duty-cycle, Speed and Current mode
- When setting the current setpoint low (<=1A), enabling current-control and moving the motor very slowly, the issue (reliably) occurs.
- At higher current setpoints (>= 2A), I cannot replicate the glitches
Setup
- Motor: A cheap NEMA17 brushless-DC motor (which is NOT a stepper), this motor has salient poles and thus also quite significant "cogging"
- Feedback: An AMT10E3 encoder, set at 1280 pulses/rev (5120 counts/rev)
- Power supply: 30V/10A switching lab power supply (Owon SPE3103). I have no way of dissipating braking energy, so regen current is set to 0A on the VESC
Thank you in advance for any suggestions and ideas!
Best regards,
Gijs
Hi VESC forum,
I think I found my misstake, (ofcourse) right after I decided to post my question on the forum
. I noticed that the current-control glitch would only occur in the direction opposite to the torque, so my new hypothesis is that the current controller briefly sets the duty-cylce "negative". This is not possible, because the regen current (in my setup) cannot be larger/smaller than 0A. I verified this, and it turned out to solve the issue. So thanks if anyone wanted to help out, I hope my self-comment can maybe help in similar issues in the future :)
Best regards,
Gijs