Author Topic: Stepper Motor Power Supply  (Read 643 times)

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Offline AbhishekAnandTopic starter

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Stepper Motor Power Supply
« on: March 09, 2014, 07:35:59 AM »
I am using these stepper motors for my project.

1. 19 kg-cm, 3.2 V, 2.8 A
     http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=350

2. 10.2 kg-cm, 3.3 V, 2 A
     http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=349

3. 4.2 kg-cm, 1A
    http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=442

My problem is the voltage ratings of these motors.
I know that the torque developed by the motor is proportional to the current through it but I am not sure how the voltage applied affects it. I want to understand that first.

Then, next question is, can I use a simple L298 based motor driver to control the motors. L298 IC can handle a max of 4A at a time, which is more than enough for these motors. What about the voltage. How can I provide exact voltage (3.3 V or 3.2 V) to the motor. What if I don't give the exact voltage and use a 5 V or 12 V supply? 

The motor driver board that I am planning to use has only one supply. It then uses a 7805 voltage regulator to supply the L298 IC.
If I jack it up to a RPS at 3.3 V & 2 A, will it work ??

This is the driver I  am using.
http://probots.co.in/index.php?main_page=product_info&cPath=54&products_id=197

Thanks. :)

Offline jwatte

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Re: Stepper Motor Power Supply
« Reply #1 on: March 09, 2014, 10:13:26 PM »
The voltage rating specify which constant voltage will, after a bit of time, generate the rated current.

For motors that move, this isn't very useful. As long as you have a controller that lets you limit the current (typically, a chopping controller,) you want the voltage to be as high as your controller will let you; this lets your controller drive the current up to the desired value as fast as possible, to overcome the inductance of the windings in the motor.

Offline AbhishekAnandTopic starter

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Re: Stepper Motor Power Supply
« Reply #2 on: March 10, 2014, 08:04:17 AM »
I looked over a few drivers and what I find mostly is people suggest using a Pololu driver.
Its difficult for me to get one of those here, because Pololu doesn't sell directly in India, but only through some distributors.

The ones I can find here are like one of these.
http://probots.co.in/index.php?main_page=product_info&cPath=54&products_id=453 

Or, maybe these could help. They are expensive but maybe this is  my last option.

1. http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=387
2. http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=451
3. http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_4&products_id=384

If not, I will have to think of some alternatives for the steppers. Maybe low RPM DC geared motors.

Offline jwatte

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Re: Stepper Motor Power Supply
« Reply #3 on: March 10, 2014, 10:36:53 AM »
The L297/298 based driver you link to can probably work, especially for the lower-current motors.
The higher-current motors will likely draw too much to be well behaved with that driver.
When the motor specifies 2.8A, that's likely per winding.
When the L298 driver specifies 2A, that's in total, across both windings.
Thus, the L298 2A driver can drive two 1A windings reasonably well, but not two 2.8A windings.

There are also stepper drivers you can buy from CNC shops. You may also be able to find them on eBay.
For examples, see here:
http://www.ebay.com/itm/CNC-Router-Single-1-Axis-3-5A-TB6560-Stepper-Stepping-Motor-Driver-Board-Control-/231041654828
http://www.ebay.com/itm/CNC-One-Single-Axis-TB6560-3-5A-Two-Phase-Hybrid-Stepper-Motor-Driver-Controller-/231018725954
http://www.amazon.com/Nextrox%C2%AE-HY-DIV168N-Hybrid-12~36V-Stepper/dp/B00HJ038CG

Offline AbhishekAnandTopic starter

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Re: Stepper Motor Power Supply
« Reply #4 on: March 10, 2014, 11:18:44 AM »
L298 IC datasheet says, total current of upto 4A.

And the whole IC is controlling just one 1 stepper. Wont that be enough.

Offline jwatte

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Re: Stepper Motor Power Supply
« Reply #5 on: March 10, 2014, 11:52:44 AM »
Quote
L298 IC datasheet says, total current of upto 4A.

You are right! That will work up to 2A per winding then. I think you'll want a heat sink on that chip, though.

The L297 can provide chopping control, so that board you linked to will work for each of the three motors, BUT you won't get full power out of the highest-rated motor.

Offline AbhishekAnandTopic starter

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Re: Stepper Motor Power Supply
« Reply #6 on: March 10, 2014, 12:22:27 PM »
Ya exactly, I think I will have to go with 297/298 combination.

Thanks for the help.  :)

 


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