1Nm torque motor for my solar panel cleaner !

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 : https://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,

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,

Hi,

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

Click to expand...

The voltage in the table is for "non moving".

The voltage in the diagram is for moving, maybe it's the driver bus voltage. I assume the datasheet explains that.

Klaus

I don't believe that a stepper motor, particularly with 1.8° step angle, is an effective drive for your application. For the expectable low duty cycle, a geared brushed DC motor seems preferable.

but a with DC geared motor the rotation will depend on the load, for example look at this motor , https://www.farnell.com/datasheets/...06.1976950247.1511042926-397067586.1498505838

you can see the charts in the second page of the torque vs RPM,
you can notice that the speed depend a lot of the frequency,




with no load It run at 500 RPM and when we add a 1Nm torque the speed drop, and at the maximum torque accepted by this motor which is 5Nm the speed drop to 15RPM.

You misunderstood the diagram. It's showing available torque with different gear ratios.

A brushed DC motor may show up to several 10 percent speed drop between no load and full rated load. The effect is mostly linear according to rotor resistance and can be compensated in the first order.

The linked DC motor has however insufficient power for the intended application. 1 Nm @ 450 rpm refers to 47 W mechanical, efficiency of geared DC motor isn't particularly high.

Brushless DC or high performance brushed DC without gear has probably the highest efficiency. Question is if your mechanical design is already fixed to 450 rpm shaft speed?

yes the design is fixed to 450 RPM / 1Nm