Re: 3 phase motor math

How important is it to match the VFD to the motor ?
Can using a motor with a higher or lower inductance than the VFD is
designed for cause damage to either ?

I was hoping to use an old AC servo motor to power a spindle, so my
main concern is if the VFD will spin the motor without blowing either.

Rab

> Generally, no, or at least not recommended. I popped an early and

crude

> VFD this way. The reason is larger motors have lower inductance.
> The VFD is designed to take that into account. The PWM waveforms
> are not designed for the lower inductance motors, and may cause

magnetic

> saturation. You could put inductors in series with each motor wire

to

> bring the inductance up to the right range. I had to do this to

run some

> air bearing high speed spindle motors from a standard VFD.
>
> >Could a VFD be used to run an AC servo ?
> >
> >
> Generally, no, because they do not excite the rotor flux at zero

speed, and

> they respond way too slow to dynamic changes in the speed command.

If

> you could live with dynamic response of about 1 Hz, then it would

mostly

> work,
> except for some jitter when sitting still.
>
> Jon