High Current stepper motor driver

Using Arduino Motors, Mechanics, Power and CNC
1

Hello All,

I'm trying to control 2 bipolar stepper motors (57BYGH78-401A), both rated at 3A per coil. I have been using the A4988 driver with a RAMPS 1.4 board and a Arduino Mega, however after testing it appears the current limit of the A4988 can only be set up to about 1.3A (can someone confirm this?), and the motor appears to not have the torque required for my application. I have read that the torque is proportional to the current, regardless of the voltage, is that correct?

I have looked at getting the DRV8825, which is rated up to 2.5A(?), which has the advantage of being interchangeable with the A4988 on my RAMPS board.

My question is, will the DRV8825 actually give me 2.5A (the A4988 was supposed to be rated at 2A and could only be set at 1.3A), and is this likely to give me a noticeable increase in torque?

Otherwise, what are some higher current drivers that can drive my motor at its full capacity? I presume any other drivers will need to be wired into my RAMPS board as they will not just fit in the slot.

2

The DRV8825 can only provide about 2 amps.
Have you tried heat sinks and cooling fans for your A4988s? They would probably also be needed with the DRV8825s.

You need to get a high current driver - search Ebay for drivers with (say) 4 or 5 amp capacity. Gecko and Leadshine are two brands that spring to mind.

Alternatively change to motors that are compatible with the A4988 or DRV8825.

...R
Stepper Motor Basics

3

If you need the full available torque from those motors, your only option is an industrial driver. There are a couple of reasonably priced offerings from Gecko, e.g. the G251X.

4

You'll not get the full rated current from any single-chip stepper driver unless you use large
heatsinks and a fan (or water cooling). These are the absolute maximum ratings, ie don't
expect to get to that level.

NEMA23 high performance steppers are generally outside the range of single-chip drivers.
If you don't need high speed then you should have gone for a unipolar motor.