Stepper motor too hot

[metRo_]

Hi,
I'm using the following stepper motor Bipolar, 200 Steps/Rev, 20×30mm, 3.9V, 0.6 A/Phase with a A4988 Stepper Motor Driver.

After some minutes it get too hot. So hot that It boils a water drop :s

The power source is 9v, measured with the multimeter it is comsuming 600mA/700mA (limited on the driver).

It is normal that it gets to hot?

Thank you

[nickm]

No. A lot of stepper drivers have a way to adjust the current provided to the motors which will.  The motor driver page you linked has a section on current limiting.  Try reducing the current limit and that will reduce the power dissipation.

[metRo_]

No. A lot of stepper drivers have a way to adjust the current provided to the motors which will.  The motor driver page you linked has a section on current limiting.  Try reducing the current limit and that will reduce the power dissipation.

I limited it to 600mA, if I reduce it more it doesn'h has enought torque for my application. I'm +- inside the parameters, I expect it to be hot but not too hot.

[Zbig]

Dude, haven't you missed the 3.9V vs. 9V part? You're pumping almost 2.5 times the rated power through that motor.

EDIT:
Ah, only now I read you did limit the current...

[Rufus]

I limited it to 600mA, if I reduce it more it doesn'h has enought torque for my application. I'm +- inside the parameters, I expect it to be hot but not too hot.

It is a switch mode driver so the supply current is not same as the motor coil current.

The motor is specified with a +80C temperature rise at the rated current, and that probably assumes some heat sinking from the motor mounts. The specification is telling you it will run above 100C.

[Alex]

The higher the voltage you run the motor, the higher the rate of rise of the current through the windings.

The integrated PWM current regulator might have a minimum on time. Also, the current limiter will have an associated delay to it, so you should not rely on current limiting to tame the PWM regulator. In other words, I suspect your RMS current through the motor, coupled with the high supply voltage causes excessive power dissipation.

Try using a motor with higher winding inductance - usually more turns and higher voltage. That will also increase your torque and reduce your current drain.

Alex

[amyk]

I limited it to 600mA, if I reduce it more it doesn'h has enought torque for my application. I'm +- inside the parameters, I expect it to be hot but not too hot.

It is a switch mode driver so the supply current is not same as the motor coil current.

The motor is specified with a +80C temperature rise at the rated current, and that probably assumes some heat sinking from the motor mounts. The specification is telling you it will run above 100C.

I've seen stepper motors in office equipment (big faxes, copiers) with big red "HOT!" stickers on them --- they do get over 100C easily and keep working. Some of them have forced cooling via fans too.

Edit: your stepper has class B insulation good for up to 130C.

[george graves]

If you need cooling for your steppers, you might look at what the reprap 3d printer guys are using.  NEMA 17 is mainly what the reprap guys use - so if you're using 17's you might be in luck - there are some cheap options now-a-days.

[poorchava]

Steppers may get hot. the ones that I have in my CNC machine were about 70...80 deg.C when running at 1.7A driven by TB6560.