Re: [CAD_CAM_EDM_DRO] Variable speed drives

turbulatordude wrote:

>Hi all,
>
>I'm looking into putting a variable speed drive on my lathe and am
>wondering about the different type of drives.
>
>I have seen ones optimized for HVAC, some constant torque, others
>like sensorless vector control, flux vector....
>
>

The basic VFD will do all you want, in most cases. All of them have
constant torque up to motor rated speed, and constant power above that.
Sensorless vector and flux vector are pretty similar, and are for
positioning requirements. You don't need to position your motor, so
a plain VFD will do fine. The only thing you really want to make sure you
get is the transistor for dynamic braking. Some of the cheapest units
don't have this transistor built in, so you can't decelerate the motor.
The standard VFD will have this feature in it, and you can then add
an outboard braking resistor to absorb the energy as the motor is
slowed down. Dynamic braking on larger lathes is extremely useful
on lathes that don't have clutch/brake systems, as you can stop the
spindle in less than a second.

Jon