Re: [CAD_CAM_EDM_DRO] Re: Adequate torque from VFD driven motors?

scyvt wrote:

> Perhaps a dc motor and controller would be also worth considering,
> especially if that would address my concerns about low-end torque while
> keeping the 1 1/2 hp factory spec.

Well, horsepower = torque * rpm, and while both VFD-driven AC motors
and DC motors can retain most (possibly, all) of their torque down to low
rpm, they most certainly will not retain 1.5 HP at any speed other
than top speed.

> So, how do ac & dc spindle drives compare in terms of cost,
> performance, availability, and ease of CSS implementation.

AC: motors very cheap, VFD drives expensive
DC: motors expensive, DC drives relatively cheap compared to AC VFD drives.

Taken as a group, AC motors/drives are probably cheaper overall because
you probably already have the AC motor in your equipment. Some people
think DC is better for higher powered 5-50HP lathe applications.

> And how do the several dc control approaches compare?

Same, both have either analog input speed control (0-5V, 0-10V, -10 to +10V)
or PWM (pulse width modulation), or maybe even serial control (RS422/423).

best regards
Doug Fortune
http://www.cncKITS.com













-