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

Tom,
These are PWM controlled full wave SCR rectified straight from the AC line.
Torgue and speed regulation is taken from the back emf of the motor.
These are killer drives. I highly recommend them.
KB Electronics and Minarik are two manfs of excellent drives.
These are for DC motors what VFD's are to 3 ph motors.
Some units will accept 120 or 240 VAC giving 90 or 180 DC out.
The motor volts does not have to be closely matched.
RichD

ths992001 wrote:

>
> --- In CAD_CAM_EDM_DRO@y..., "Jan Kok" <kok@s...> wrote:
> > How does one get 90VDC from 110VAC?
>
> I have been wondering about this for a long long time...
> The 90vdc drives that I have seen have no transformer, just SCRs.
>
> I suspected half-wave rectification:
> 120*sqrt(2)~=170, and half of that is 85
> (this is simplified, but it works out in RMS too)
>
> But I understand that drawing DC from an AC power line is not a good
> idea.
>
> So how does it really work?
>
> Tom Scarince
> www.thsengineering.com