which 1Nm motor should I choose for my solar panel cleaner ?

[Tizana]

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,

 

[kellys_eye]

What's wrong with a standard commutising (brushed) motor? You can get them in many voltages and with gearbox reduction. No elaborate control circuitry (on-off!) and just a pair of limit switches.

 

[Tizana]

What's wrong with a standard commutising (brushed) motor? You can get them in many voltages and with gearbox reduction. No elaborate control circuitry (on-off!) and just a pair of limit switches.

thanks for the answer,
can you give me an exemple where can u buy 1nM brushed motor with gearbox please ?
with these gearbox ma i still able to control the speed of it?

here's a list of geared DC, the price seems too high and the RPM is too low for most of them:
http://uk.rs-online.com/web/c/autom...chTerm=dc motor&applied-dimensions=4294570803

 

[kellys_eye]

Use a windscreen wiper motor.

Consider using the complete mechanism to perform the wipe cycle too. Even the 'new' prices are lower than those RS motors! and you can source used ones from scrapped cars to experiment with.

 

[Tizana]

Use a windscreen wiper motor.

Consider using the complete mechanism to perform the wipe cycle too. Even the 'new' prices are lower than those RS motors! and you can source used ones from scrapped cars to experiment with.

stepper motor are cheaper , aren't they the best option ?

 

[NMNeil]

I can see a long term downside to your idea.
A dry brush, rotating at 450RPM on a dusty gritty surface with no water/detergent solution would quickly damage the panel surface, which is possibly an EVA film rater than glass.

 

[kellys_eye]

stepper motor are cheaper , aren't they the best option ?

Good luck finding a 'cheap' stepper that is capable of 1Nm at 450 rpm!

Car wipers systems (including the wash facility) would be an ideal method - cheap, reliable, easy-to-obtain (including spares) 12V operation - no controlling electronics (or basic at the minimum) etc.

 

[Tizana]

guy i need your opinion about this stepper motor ,

i found this one : https://www.digikey.com/product-detail/en/QSH5718-76-28-189/1460-1080-ND/4843431?utm_campaign=buynow&WT.z_cid=ref_octopart_dkc_buynow&utm_medium=aggregator&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,

 

[BobK]

Due to the inductance of the coils, you need more voltage as the RPMs increase. The 3.2V number is likely the stall or holding current, i.e. when it is not moving.

Bob

 

[Minder]

The bottom line is the Mean current through the motor should be maintained at exactly the rated plate current, regardless or RPM.
M.