Re: [CAD_CAM_EDM_DRO] Stepper Motor Driver

juan gelt wrote:

>ew...that is bad...
>i just checked a data sheet which said that reverse
>diode max was 4v, though. and that delay was
>apparently so small they couldn't give it a
>number...is this cuz of improved versions perhaps?
>

It depends on the circuit, and the circuit I've been using is
quite different. The big problem is when an inductor is
sourcing something like 20 Amps from the + supply out
the motor terminal. Then, the transistors switch, and the
connection between the supply and the inductor is cut.
Current has to keep flowing in the inductor until the low-side
transistor is fully on. That is the tough situation, it doesn't
show up in the same way on a unipolar drive.

>have i not had a problem cuz of only using unipolar
>steppers? (and optoisolated driver circuitry?)
>
>

Yes, it is a simpler circuit, and the pure inductance in my
circuit is most likely much more muted with the stepper motor.

My problems with the undershoot is in a 20 Amp servo drive
running above 100 V into a dead short on the test bench.

Jon