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Stepper Motor Controllers and voltage regulators

Dylan Darcy

Nov 20, 2016
1
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Nov 20, 2016
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I'm trying to use an Arduino with two Adafruit V2 motor shields to control four stepper motors. The motor shields can supply 5-12v, but the steppers i have are 3.3v, 2ohm. If i run the steppers directly off the motor controller they will draw 2.5A, which is more than the controller and motors are rated for.
I'm controlling everything from matlab, which has support packages for arduino and the V2 shield, making the programming very easy, so i don't want to change the motor shields, and changing the motors could take a few weeks, so I'm considering alternative ways of making it work. I'm aware that i could put power resistors in series with the motors to get the right current, but this is obviously very inefficient. I have two possible work arounds in mind at the moment, either using voltage regulators, or mosfets to switch a separate power supply on and off, so my questions are:

1) If i send the 5v pulse signal from the stepper controllers through a 3.3v voltage regulator, with no capacitors, will the pulse signal be preserved, and what will the current be?

2) If i set up a separate 3.3v supply to the motors and use mosfets to switch it with the 5v signal from the controller, will the signal be preserved?

I'm a mechanical engineering student, so my knowledge of electonics is basic, any advice is much appreciated.

Here is the stepper motor spec sheet:
http://robocraft.ru/files/datasheet/42BYGHW.pdf

The Motor shield:
https://learn.adafruit.com/adafruit-motor-shield-v2-for-arduino/using-dc-motors?view=all

And a possible voltage regulator:
http://ie.rs-online.com/webdocs/11a6/0900766b811a65c5.pdf
 

BobK

Jan 5, 2010
7,682
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Jan 5, 2010
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7,682
You are using the wrong driver for the motors. Change one or the other of them until they match.

It sounds like this is just a PWM driver. A real stepper motor driver will use a higher voltage and PWM to achieve the desired current in the coils. The voltage to run a stepper motor changes with the speed it is run at. The faster it runs, the more voltage you need due to induction of the coils. The rated voltage and current are only for DC or very slow stepping. You could implement this type of algorithm with the driver board you mention, but there are boards out there that do all of this for you.

Bob
 
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