I've been working on this for a while now and have already bought a bunch of stuff to drive this high amp Stepper and it hasn't worked out.
So before I buy anymore, I'd really appreciate if someone could please look over my setup and make sure I'm headed in the right direction.
The basic idea is right but you have a couple of problems.
The MOSFET is not a logic-level MOSFET, thus it's on-resistance of 0.06 ohms is only achieved when the gate-to-source voltage is >10V. You're only going to give it 5V. You should use a "logic-level" MOSFET like the NDP6060L.
Additionally, the gate of the MOSFET presents a very large capacitive load to the microcontroller, which can damage it. You should have a series resistor at each gate terminal (470 ohms is a good start).
Grounding is going to be important. You're using a common ground between MOSFET's and motor but the physical details are important. A "star ground" configuration is suggested.
If you pulse-width-modulate your phases to 70% or so instead of leaving them on all the time you can compensate for the overvoltage. You'll get about 70% of the current that you'd get if you just applied 5.1V (so 0.7*5.1/2.3 --> 1.55A). You might want to reassign your pins to ones that have PWM capability.
Other than that, the basic setup looks OK. Start small (<5.1V) and work your way up in current if things look good.
Pretty close. The grounding thing isn't right though. You don't want high currents travelling on the current loop that goes to the Arduino. Think about having a star ground at each MOSFET. A ground wire goes from the Source terminal to the Arduino (will carry very small currents, enough to charge/discharge the gate) and another ground wire goes to the power supply (will carry large motor current). Repeat 4 times. There's a star ground at the big power supply. At the Arduino it doesn't matter too much since the currents are small.
I know the voltage of 5.1V isn't perfect (1.5A*2.3Ohms=3.45Volts)
It's not perfect, no - but for the time being just to get your motors turning (slowly) it'll be fine.
It may surprise you, but "over volting" as it's sometimes called is not only common practice but absolutely neccessary if you want to strive for the maximum performance your motor is capable of in terms of torque and speed. But to use it successfully you have to employ current limiting. (don't go over the rated current/phase - your motors will never forgive you)
For the time being I'd stick with your PS and go with the "resistive" current limiting technique because it's arguably the simplest. Later on though, you might want to look at better methods for example linear current limiting and (in my view) the best for driving steppers, the so called "chopper" technique. Then you'll be able to use the ideal PS voltage for your motors which is 60V. (yes sixty volts dc) Then you'll really see that puppy scream.
If you go over the rated amps you will piss off the injuns and they will send out smoke signals. They're hyped up on booze and pot so you might be able to get by with a substantial over current/voltage without such gross displays but you will weaken them. Poor injuns.
But as long as I have two phases on at the same time, won't that split the 3 amp current from the power supply into 1.5 amps per phase?
No without any current limiting your motor will be trying to pull 5.1/2.3 = 2.21 Amps per phase. that is a total of 4.42 Amps from a supply rated at 3A. What will happen therefore is that you might get the over current protection of your supply kicking in or your supply will drop it's output voltage and overheat, or your supply (if it is switched) might blow up.
But mrmeval said it so much better than me.
So you do need some current limiting to protect you power supply let alone your motors.
Oh bummer.
Well, thanks again. But I think this project is getting beyond me.
Maybe if anyone knows of a fully built Driver that I could use to power a 1.5 amp 2.3 Ohms Stepper, that might be the way to go?
Or if not, does anyone know of a Stepper Motor with High Torque (around 60 oz-in) that will work with something like easy driver (but that doesn't require soldering)?
Or some other solution I could use for automation but for dummies.
