Re: [CAD_CAM_EDM_DRO] DIY AC servodrive questions

> Anders,
> I'd have to know more about your drivr/motor topology. Commecial
> drives are usually configurable for torque or speed. PID is just a
> cause/effect thing and will work with torque signals, velocity signals, or
> even open loop amps. The tuning is different.
> Let me ask a simple question about what you have now:
> If the motor is running at speed with some control voltage input....and if
> you suddenly make the input control voltage zero...does the motor coast or stop abruptly?
> Les
>

It stops, more or less quickly, maybe in 0,5s to zero.
I can't test very abrupt stops right now since the lab-powersupply has
overvoltage protection which trips if I turn down the speed pot really
quickly...

That brings up another thing I probably need: overvoltage detection and
a 'dump' resistor in the powersupply. Would a simple comparator and a
relay work ? (I'm concerned that a normal relay might not be very quick
??) What value and wattage resistor would be OK ? I'll be using three
400W servos for XYZ and one 1kW for the spindle. I have a 3 kva
transormer on order.

AW