Re: query - 2HP PM DC motor controller - pointers please

--- In CAD_CAM_EDM_DRO@y..., "tedinoue" <etinoue@c...> wrote:

> I recently purchased a 2HP PM DC motor, hoping to build/buy a
> controller so that I could use this on a small lathe. For those
> interested, it's a Leeson motor, designated 120v 14A, 4800 RPM.
> Model C42D340T7A. I plan to reduce the maximum speed then feed it
> into my existing lathe drive system.
>
> Several questions:
> 0) the motor doesn't have any designations about reversability. I
> know electrically it works, but I'm not sure if the brushes are
> rated for reverse motion. As I manually rotate the shaft, the
> brushes sound smooth in one direction and click lightly in the
> other. Should I assume that the motor is designed for one direction
> rotation only?
>
> 1) I've seen a lot of postings discussing 90v DC from 110v AC and
> 180v DC from 220v AC, but little to nothing on driving a motor

rated

> for 120v. I'd get plenty of power out if I ran it at 90v, so I'm ok
> with a controller that does the basic 110AC -> 90DC conversion. Any
> reason why this wouldn't be suggested?
>
> 2) If I do run it at 90VDC, that's 3/4 of 120VDC, so would I simply
> then treat the controller needs as 1.5HP / 90 VDC and 10.5Amps?
>
> 3) I've no problem making a tach circuit to provide closed loop
> speed feedback, and from what I can tell, a PWM circuit will

provide

> the best performance. I've made my own PWM DC servo motors before

on

> a small scale using encoders and DC gear motors. Is controlling a
> large, PM, brushed motor of this sort simply a matter of scaling up?
>
> 4) not having experience in higher voltage/power design, I'd
> appreciate a pointer to a web site with some designs. I'm not
> looking for someone to give me a tutorial on this forum, and I've
> done a lot of web searches but they've turned up fairly cold when

it

> comes down to real designs for these types of controllers.
>
> Thanks for your help.
> -Ted

Try KB controls. I just bought a 5HP four quadrant regen drive from
them for $350. I think you could get a 2HP 90V armature drive for
much less.