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Tuning assistance for 8-pole BLDC motor

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Forum 1
(@ndemarco)
Posts: 3
Active Member
Topic starter
 

I'm attempting to tune an 8-pole BLDC motor - spec sheet attached, summarized here:

8 poles
740 mOhm coil resistance
50W
24V
Hall sensors, 120°
Planetary gearbox attached.

Controller:
Solo MINI v2
Firmware 0003B00E
Note: Motion Terminal shows the device as a Solo MINI v1 - unsure if that is the problem.

Connection:
Followed this guide for hall effect sensored motors, with 1 of the 6 connection permutations working properly:
https://www.solomotorcontrollers.com/blog/hall-sensors-to-solo-for-controlling-speed-torque-brushless-motor/

I've attempted to follow tuning guides on SOLO's site:
https://www.solomotorcontrollers.com/blog/setup-tune-motors-using-solo-motion-terminal/

The motor is not smooth at low speeds. The MotionTerminal settings are shown below.

Kp_torque and Ki_torque are auto-set.

With Ki_velocity set near zero, Kp_velocity will run the motor, but it oscillates. Kp too low, and the motor responds with large delays (1-2 s).

For any lower settings, the motor exhibits high torque windup.

image
 
Posted : 05/01/2023 5:11 pm
SOLO Team
(@milad)
Posts: 466
Illustrious Member Admin
 

Hi @ndemarco,

Can you share with me a full screen-shot from your Motion Terminal settings read from Express section and the Action part? 

I specifically need to see the Current controller Gains.

Thanks

Milad

 

If you found the answers helpful and you could solve your problems, please kindly verify here to help others in the future.

 
Posted : 05/01/2023 8:37 pm
Forum 1
(@ndemarco)
Posts: 3
Active Member
Topic starter
 
Screenshot 2023 01 05 120411
 
Posted : 05/01/2023 8:49 pm
SOLO Team
(@milad)
Posts: 466
Illustrious Member Admin
 

@ndemarco

From what I see, there are a couple of points:

  • Your motor has only 8 poles, but in the motion terminal, I see 24 poles, is that correct? if not, please remember that after modifying the number of poles to 8, you need to redo the Hall calibration, as that's a critical parameter for offset computations.
  • you put an Acceleration and Deceleration of 1 rev/s^2, which is a very slow motion, is that necessary? certainly, with such a low value the startup will take a long time.
  • it's always good to have a small value for Speed controller Ki gain, to have high accuracy speed tracking, thus I believe you can put a value like 0.005 or 0.003 for it just to have a zero steady-state error.
  • Your motor has only 8 poles, and using Hall sensors, the resolution of your motion is only 24 pulses per mechanical turn ( 8 x 3), having this, it's very hard to achieve low speeds like 10 RPM, for instance, if your motor had 30 or 40 poles then it was easier using Hall sensors to reach to such speed, another solution for your application is using Incremental Encoders, for instance with an incremental encoder with 1000 lines, you can probably achieve to 5RPM or less.

let me know about these points and if any progress happens.

Milad

 

If you found the answers helpful and you could solve your problems, please kindly verify here to help others in the future.

 
Posted : 05/01/2023 9:09 pm
SOLO Team
(@milad)
Posts: 466
Illustrious Member Admin
 

Posted by: @ndemarco

Note: Motion Terminal shows the device as a Solo MINI v1 - unsure if that is the problem.

Sorry, I forgot, Can you tell me the Hardware Version that you are reading in the Motion terminal? it's readable in the Express section, Action part.

Milad

 

If you found the answers helpful and you could solve your problems, please kindly verify here to help others in the future.

 
Posted : 05/01/2023 9:11 pm
Forum 5
(@cbrown)
Posts: 1
New Member
 

@milad It looks like we're using  Hardware version 2000F002 

Screenshot 2023 01 06 132724
 
Posted : 06/01/2023 6:27 pm
SOLO Team
(@milad)
Posts: 466
Illustrious Member Admin
 

Posted by: @cbrown

It looks like we're using  Hardware version 2000F002 

For some reason that is not clear yet to su, your SOLO MINI V2 is having the V1 firmware, this won't affect the functionality in your particular case, but it's better you send an email to support[at]solomotorcontrollers.com to receive the right firmware for your controller.

Regards
Milad

 

If you found the answers helpful and you could solve your problems, please kindly verify here to help others in the future.

 
Posted : 11/01/2023 8:13 am
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