Re: steppers

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:

>
> The series connection has minute advantage over the parallel
> in holding torque at standstill, but suffers vastly in speed.
> The series connection has 4 x the inductance of a single
> winding, and the parallel has 1/4th the inductance of single,
> so you end up with 1/16th the inductance in parallel, thereby
> allowing the motor to run 16 times faster in parallel.
>
> (At least, it seems like it should work that way as separate
> coils on the same magnetic components.)
>
> Jon

Series has 4x the inductance of single winding, but parallel
has the same inductance as single. Think of parallel as if
it was a bifilar (sp?) winding. With the endpoints of the
windings connected together (paralleled), the voltages on
each winding are identical at all points along the wire.
So (neglecting skin effect, etc.) you can mentally remove the
insulation between the two wires, and treat them as one thicker
wire. Parallel has lower copper loss due the the lower DC
resistance, but the inductance is the same.

That still means that single or parallel is 4 times faster than
series, and 4x is nothing to sneeze at. It's just not 16x faster.

John Kasunich