Stepper motor too hot - Page 1
Forum section: electronics / projects

author: metRo_
author_rank: Regular Contributor
timestamp: November 03, 2013, 05:07:59 pm
content: Hi,I'm using the following stepper motorBipolar, 200 Steps/Rev, 20×30mm, 3.9V, 0.6 A/Phasewith aA4988 Stepper Motor Driver.After some minutes it get too hot. So hot that It boils a water drop :sThe 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

author: nickm
author_rank: Regular Contributor
timestamp: November 03, 2013, 06:02:50 pm
content: 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.

author: metRo_
author_rank: Regular Contributor
timestamp: November 03, 2013, 06:10:45 pm
content: Quote from: nickm on November 03, 2013, 06:02:50 pmI 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.

author: Zbig
author_rank: Frequent Contributor
timestamp: November 03, 2013, 06:58:35 pm
content: 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...

author: Rufus
author_rank: Super Contributor
timestamp: November 03, 2013, 09:27:16 pm
content: Quote from: metRo_ on November 03, 2013, 06:10:45 pmIt 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.

author: Alex
author_rank: Regular Contributor
timestamp: November 03, 2013, 10:12:32 pm
content: 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

author: amyk
author_rank: Super Contributor
timestamp: November 04, 2013, 06:29:52 am
content: Quote from: Rufus on November 03, 2013, 09:27:16 pmI'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 insulationgood for up to 130C.

author: george graves
author_rank: Super Contributor
timestamp: November 04, 2013, 08:23:40 am
content: 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.

author: poorchava
author_rank: Super Contributor
timestamp: November 04, 2013, 08:35:41 am
content: 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.