Re: Unipolar as bipolar.

Hi again Mariss,

I just read your white paper, and you said "half the power" before!
That's more along the line of what I had remembered. Good paper.

Alan

" SERIES: A method of connecting a split winding (8-wire
motor) end to
end so that the current flows through one winding and then
through
the other one. Mind the phasing of the windings; they must
be
connected so that they "add" (boost). If they are
connected
to "subtract" (buck), the result will be no torque and
possible
damage to a switching drive since the inductance will be
zero as well.

ADVANTAGES: Smaller power supply because only half of the
rated
current is necessary for the same holding torque. Less
motor heating
at a given voltage.

DISADVANTAGES: The motor will develop only half the power
at higher
speeds because this connection has 4 times more
inductance.

PARALLEL: A method of connecting a split winding (8-wire
motor) side
by side so that current flows through both windings
simultaneously.
Mind the phasing again (see SERIES: above).
"

Mariss Freimanis wrote:

>
> Alan,
>
> Any 6-wire motor can be driven in a bi-polar mode. Bi-polar refers
> more to the drive type than the motor.
>
> Full winding (center tap unused), is exactly equivalent to a series
> connected motor. 4 times the inductance, use 1/2 rated current, get
> 1/2 the power of a parallel connected motor for a given supply
> voltage, same holding / low speed torque.
>
> Half winding (end wire and center tap used, other end wire unused),
> is virtually identical to a parallel connected motor (within 3%). Use
> rated current, get rated holding / low speed torque.
>
> If interested in more detail, please see message #8239 (June 18).
>
> Mariss