Re: [CAD_CAM_EDM_DRO] How to deal with Stepper Motor heat - 150 degrees F

lcdpublishing wrote:

>Hi guys,
>
>I ran a test the other day to see how hot the stepper motors are
>getting on my machine. After 30 minutes, they (3 of them) were all
>at 150 degrees F.
>
>The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
>driving them at 30 volts and 1.4 amps. The driver chip is the
>SLA7062M chip. This heat test was performed with the motors holding
>their position as that is the best way I know to "push them" for
>heat build up.
>
>I know I could get another transformer and drop the voltage, but
>would prefer to keep it at 30 volts for performance. I have a bit
>of room where I could add some chunks of aluminum for heat sinking,
>but not sure if that would get the temp down enough. I have no room
>for fans so I am sort of pondering what directions I can go to deal
>with this.
>
>

What you might look into is a scheme to drop the current when the motor
is standing
still. Gecko drives drop to 1/3 current 1 second after motion stops,
and back up
to full current as quickly as possible when a step pulse comes in. The
circuitry to
do this is basically a one shot and a transistor to change the reference
voltage to
the dac that produces the microstep sine waves. A similar circuit that
changes the
current limit threshold should do what you need.

Jon