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TOPIC: Noise at low speeds

Noise at low speeds 9 months, 3 weeks ago #2198

4.15C firmware
2013 manufacture date
powered at 24V

Is noise a low servo motor speeds a normal occurence? If so is there anything that can be done to improve it? Would moving to a larger frame size improive low speed performance? I get a squeak and squeal sounds from the motor under the following conditions. The noise is very audible seems to be coming from the motor windings. Auto-tuning in SMI with setting "1" returns the same values as default.

- speed under 50RPM
- very lightly loaded, in index table application tat tracks an external event
- default pid values
- servo sent updated position commands 10-20 times a second
- moving betweeen 100 and 1000 encoder counts per command

Thanks in advance for any help you can provide.


Re: Noise at low speeds 9 months, 3 weeks ago #2200

  • csearcy
  • Posts: 480
  • Karma: 23
Hi Daniel,
The motor you have can only do trap commutation off the hall sensors, so slow speed operation isn't very good. If you change over to the newer class 5 motors, they can commutate off of the encoder and perform very well at slow speeds. The only trick is you have to make at least one full rev of the motor before it will enter sine commutation.

Re: Noise at low speeds 9 months, 3 weeks ago #2201

Thanks Chuck:

at what point does the full rev have to be done? If I do one full rev on startup (which I do, to index the drive train), and then start and stop numerous times, is that enough to engage the sine commutation?

Also will the noise be reduced to a non-audible level with the class 5?


Re: Noise at low speeds 9 months, 3 weeks ago #2202

  • csearcy
  • Posts: 480
  • Karma: 23
One full rev at startup will do it. It's hard to claim it will be non-audible, but it's much less audible.

Re: Noise at low speeds 7 months, 1 week ago #2217

Thanks for the CLass 5 tip-- I got an SM23375D, ran it in Sinusoidal commutaiton mode and the noise is greatly reduced at low speeds.

I also discovered that by mounting the motor with rubber isolation mounts (Essentra QM1T) and Keystone brass standoffs further reduced any vibration/noise transmitted by the actual motor.

Then (yes, there's more), I added a rubber spider coupler (Lovejoy L035 series), the system becomes more or les silent at speeds under 300RPM.

Thanks for your advice.

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