Re: Power Supply for 4-axis CNC stepper driver

> >Interesting. If the motors are 2.4 volts and 6 amps or 14.4 watts
> >times 4 motors for 57.60 watts total, why is the secondary selected
> >for 1,032 watts ? (43 volts times 6 amps time 4 motors ?) why not
> >the 60 VDC final voltage times 6 amps times 4 motors ? (1,440 watts?)
> >
> >
> The 14.4 W (plus some iron losses
> in the motor and switching losses in
> the driver) is the power dissipation
> when standing STILL, only. When
> accelerating, the power requirement
> (that's not all loss, the motor's shaft is
> delivering real power) goes up dramatically.
> It can rise to about 60 * 7 * .66 = 277 W
> per motor.
>
> Except under exceptional conditions,
> it is pretty hard for a machine
> to require this kind of power for
> very long, however. So, a power
> supply that can deliver that power
> (X number of motors) for only an
> instant will do OK.
> Bulk, unregulated power supplies are
> easily capable of delivering short bursts of
> power above their continuous ratings.

Hi Guys,

I'm back and reading thru the posts.

The basis starts that the namepalte current is used to hold in
posistion. Fine, that makes sense.

Noboby argued with what Steve had said that more current is needed to
overcome the back EMF in the coil, so I'll work with that.

and it seems the agreement is that more power is needed as the motor
is acelerated. This is interesting as over the years I have seen a
lot of people ask why their steppers are missing steps. This
certainly can be one reason.

The motor we were discussing as 2.4 volts and 6 amps. and we were
using 60 volts as the DC power supply.

Jon, you mentioned that an acelerating motor can go up to 60 * 7 * .66

I'm not sure where the 7 comes from. Can you elaborate on this formula ?



Dave