Hello there,
I'm about to embarking in a very important project. I plan to use a full trim DMC-30000 1-Axis to control a zero-cogging BLDC motor via a linear amp. Only target is rotary speed control, no cogging, no torque/velocity ripple.
Given my lack of knowledge I will need a profesional system integrator but meanwhile I got some doubts I would like to ask here:
I understand the best way to control rotational speed with a 3 phase BLDC motor is using sinewave commutation. Then my question, how much better is a rotary encoder than Hall sensors ?
And what about the speed control for the rotary table, will I need yet another encoder there for control feedback? with a second controller ? or I can make the job with just one controller ?
Thank you in advance.
Best regards,
C. Abbiendi
Bangkok-Thailand.
Galil_AndyH on 07/16/2012 - 08:24
Then my question, how much better is a rotary encoder than Hall sensors?
- You will not be able to run a sinusoidal commutation drive with only hall sensors (at lease you won't be able to utilize the sinusoidal commutation), so a rotary encoder is going to be required.
And what about the speed control for the rotary table, will I need yet another encoder there for control feedback? with a second controller? or I can make the job with just one controller?
You don't need a second controller, the DMC-30000 has 2 encoder inputs and can run in a dual loop mode. See the DV command in the command reference. As far is if you need to encoders, this is system dependent. For best positioning control, 2 encoders would be recommended.
Are you going to be interfacing to an external amplifier?
Go ahead and e-mail support@galilmc.com with your responses.
cabb on 07/16/2012 - 19:51
Thank you Mr. Herum.
Yes, we will use a linear drive aplifier. It can't be PWM for our application.
I will contact Galil Support.
Regards,
Claudio Abbiendi
Bangkok-Thailand.
LeGa on 09/13/2012 - 00:21
Hi Claudio,
pay attention that linear amp for BLDC is more expensive (2 times at least) vs PWM one. And most single axis servo controller with build-in amplifier as CDS or DMC-3xxxx (Galil), Elmo,AMC,Copley,etc. has internal PWM amplifier as well.
Also required speed smoothness determined mainly by mechanics as a rule.