Re: BP series 1 Boss 4 to EMC Gecko drive Power Supply retrofit

Thank you, Jon...
Between your explanation, and a similar one I found at CNCzone that led
me to this link <http://www.allaboutcircuits.com/vol_2/chpt_9/7.html>
, I was able to better understand how this circuit works. Finally! I
must say that I am very impressed by the ingenuity of the engineers who
designed that circuit.
In response to your suggestion of pulling out the saturable reactors,
rather than having 56Vdc as you suggest, I would have the lowest ac tap
at 60V on the behemouth 3phase transformer giving me over 80Vdc. There
is the possibility of using the 110v single phase transformer (T6 on my
schematic) producing 56Vdc that was used to saturate the reactors if it
is big enough to drive three motors however.
All in all, simplicity, efficiency and space are moving me towards
acquiring a more appropriate transformer and building a simple
unregulated supply and saving the existing iron and concepts for other
projects.
edgar

> >
> The Bridgeport BOSS stepper power supply is really 3 power supplies on

one

> transformer core. They follow the AC output of each secondary winding
> with a
> reactor. This reactor has another winding on it where a small DC
> current saturates
> the iron, and reduces the inductance drastically. This winding is

turned on

> when the axis in in motion, and it raises the voltage supplied to the
> motor to
> about 56 V DC. When the axis is not moving, the winding is turned

off, the

> reactor's inductance returns to normal, and it reduces the DC supply

to

> about
> 9 - 12 V DC, thereby reducing the voltage across the motor and

preventing

> overheating.
>
> So, the three secondaries provide 3 totally separate DC power

supplies.

> After
> pulling the reactors out, you should be able to set up a 3-phase
> rectifier and
> get a single, very heavy-duty DC supply. I think you'll get 56 V DC

out

> of it.
>
>
> Jon
>

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