oscilating in FOC mode, not in BLDC mode

Discussions regarding the Field Oriented Control (FOC) implementation on the VESC.
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tlonsky
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oscilating in FOC mode, not in BLDC mode

Postby tlonsky » 12 May 2017, 12:09

Hi, i operate BLDC motor via FOC. When i try to operate it in BLDC mode with encoder i can get full control via RPM (from 100ERPM to 10 000 ERPM). But when i operate the same motor via FOC with encoder and i set the ERPM to some value the motor starts oscilating very quickly. Anyone some idea what is wrong?
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arvidb
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Re: oscilating in FOC mode, not in BLDC mode

Postby arvidb » 12 May 2017, 15:43

Did you re-tune the PID controller after changing to FOC? FOC uses a different implementation (and frequency) of the speed PID controller, unfortunately, so you need to completely re-do the tuning.

hexakopter
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Re: oscilating in FOC mode, not in BLDC mode

Postby hexakopter » 12 May 2017, 18:48

I noticed the same when I were playing around with the current plot (for the pole count measurement) with my eBike hub motor using hall sensors and FOC. I was expecting that the motor would spin with the constant erpm i put into the text field, but instead it was oscillating and I didn't know why that was happening. So I think that it is maybe a bug with the old firmware, but I haven't tested if it would work like expected in BLDC mode.

slapshot136
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Re: oscilating in FOC mode, not in BLDC mode

Postby slapshot136 » 07 Aug 2017, 02:44


arvidb
Posts: 234
Joined: 26 Dec 2015, 14:38
Location: Sweden, Stockholm
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Re: oscilating in FOC mode, not in BLDC mode

Postby arvidb » 27 Sep 2017, 11:25

Yes: https://en.wikipedia.org/wiki/PID_contr ... of_methods

(Sorry for the late reply, hopefully it will be useful for someone!)


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