Hi,


so i'm making a project where a motor should drive a brush all the way up and down of the solar panel in order to clean it,

the rotation of the motor should be at 450RPM with 1nM torque,




i'm very confused concerning which type of motor should I choose (BLDC, Stepper, Brushed DC, servo …)

there are a lot of type of motors with different prices, so which one should you recommend to me?

Knowing that I want it to be as simple as possible, I would drive it through an arduino or an STM MCU.


I looked for BLDC 1Nm torque and they were rare and expensive at 1Nm, after looking little bit in the internet I noticed that stepper motor is used widely in CNC machine and other different applications and they were cheaper.


For example this one is a (1010 mNm = 1.01Nm) and it cost 55$ : https://www.digikey.com/product-det...l-gmbh/QSH5718-51-28-101/1460-1078-ND/4843429


I want to know if this one can be driven at a speed of 450RPM ? and the maximum torque is constant at 450 RPM or it depend on the speed rotation ?


For BLDC I found this one : http://uk.rs-online.com/web/p/dc-motors/8928773/

it cost 146


and I found servo cheaper which has a maximum torque of 1.176Nm at 6 V : https://www.amainhobbies.com/align-ds610-digital-servo-agnhsd61001/p190915


which one should I choose ?


Thanks,

 

Welcome to AAC!
What is magic about 450rpm? I would have thought a much slower speed, using a cheap DC brushed gear-motor (e.g. a salvaged car windshield wiper motor), would be perfectly adequate for this task.

 

+1.
For efficient choice of motor, gearing should be used for that rate of operation.
You motor would result in much smaller than a 1Nm.
Max.

 

A possible solution to an impractical project with assigned values is ITEM 5-1816, Surplus Center, US $ 15.95, 500 RPM no load, 220 RPM @16 in-lb, 12 VDC @ 22A, intermittent. For fixed RPM closed loop operation required.

 

I assume you are in UK? If so it narrows the market available.
The Hobby RC servo is not a good candidate.
As mentioned already a auto wreckers may provide some options of motors already including a means of reduction.
Max.

 

...with 1nM torque,

Geeeee.... someone from UK disrespects Isaac Newton? And then marks unit not named after person with capital letter....

 

Geeeee.... someone from UK disrespects Isaac Newton?

A Knight of the Realm, no less!
Max.

 

guy i need your opinion about this stepper motor ,

i found this one : https://www.digikey.com/product-det...gregator&curr=usd&site=us&utm_source=octopart

it has a maximum torque of 1.89Nm,

and according to the curve in the datasheet page 10, Pps(pulse per second) vs torque, for a rotation speed of 450RPM the torque is 1.5Nm which is good enough for me,
450RPM is equal to 1500 PPs (Pulse per second)


the problem is with the current rating. in the same page in the TOP they wrote VM : 30v , 2.8A/phase, while in table page 4 they put a current equal to 2.8A for a voltage rated of 3.2V ?



I didn't get it how the current still the same for different voltage applied ?

thanks for your answer,

 

The curve is for half stepping, 0.9 degrees/pulse.
At 1500 pps you get 225 rpm.
I think the 3.2V / 2.8 A is the coil current, when the motor is not rotating.

 

The curve is for half stepping, 0.9 degrees/pulse.
At 1500 pps you get 225 rpm.
I think the 3.2V / 2.8 A is the coil current, when the motor is not rotating.

thanks you for letting me noticing that, i made my calculation supposing that PPS is equivaltent to 1.8 degrees/pulse. but the curve is for halve stepping so for 0.9degrees/pulse.

 

The rated current of a stepper motor, 2.8a in this case is the constant mean current that should be applied to the stepper motor at all times, from 0 to max rpm.
This used to be done by a simple series resistor method, now done by using a P.S. higher than the rated voltage and PWM to ensure rated current through the rpm range
Max.