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Is moment of inertia too much at low rpm?

Forum 1
(@gabriel_from_onda)
New Member

Hi. I'm looking to make a very smoothly rotating platform using the SOLO MINI and a DCH-6824F motor in a 24N22P configuration with hall effect sensors. I want to use a 24V power supply, but that's flexible. The platform would have a rotational moment of inertia anywhere from 0.02 kg*m^2 to 0.04kg*m^2. I'm hoping to spin it anywhere in the range of 30 rpm to 600prm. Do you think the SOLO MINI would have any issue with the mass of the platform or the low RPM?

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Topic starter Posted : 10/11/2021 6:19 pm
SOLO Team
(@milad)
Chief Member Moderator

Hi @gabriel_from_onda

Posted by: @gabriel_from_onda

Do you think the SOLO MINI would have any issue with the mass of the platform or the low RPM?

The Lowest RPM that we could achieve so far with smooth motion using Hall sensors was around 30RPM on Firmware version 0x003B009 ( depending on the Motor number of poles, our test was done on a motor with 50 poles).

Posted by: @gabriel_from_onda

The platform would have a rotational moment of inertia anywhere from 0.02 kg*m^2 to 0.04kg*m^2

What for SOLO matters is the final delivered power to your System, so it wouldn't be very accurate for us to say what happens with that load, but in general SOLO MINI can deliver up to 500W continuously, so for instance in your case you can expect to work with 24V and 20A and I guess that much of energy might be enough to move your load with the required performance ( it's just a rough guess, as the whole design and real required power is not clear now)

Let me know if you have other questions in this regard.

Milad

 

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Posted : 11/11/2021 11:52 am
Forum 1
(@gabriel_from_onda)
New Member

@milad Do you think I'd have better control at low rpms with an encoder?

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Topic starter Posted : 11/11/2021 4:55 pm
Forum 1
(@gabriel_from_onda)
New Member

I'm looking at a 500ppr encoder rn, but I'm open to suggestions

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Topic starter Posted : 11/11/2021 5:07 pm
SOLO Team
(@milad)
Chief Member Moderator

Hi @gabriel_from_onda, surely the Encoder-based solutions are having a much higher resolution than Hall sensors, resulting to be able to reach lower speeds.

Posted by: @gabriel_from_onda

I'm looking at a 500ppr encoder rn, but I'm open to suggestions

I recommend using encoders with at least 1000 or more lines ( 4096 will be a very good choice ) if you want to have very low-speed performance, for instance, AMT102-V  that has the 4096 PPR option that is also very economic.

On the other side, one important factor for Low-speed BLDC motors is the number of Poles, so the higher the number of poles the better will be the behaviour of the motor in Low speeds in terms of smoothness, usually for applications like yours I see people using brushless motors with 40 to 58 poles.

Let me know if you have other questions.

Milad

 

 

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

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Posted : 12/11/2021 8:19 am
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