Stepper Motor Inductance

[Bob Scott]

Hi guys,

I have a pair of two phase unipolar stepper motors, model number PH266-02B from Oriental Motor. They were also available under the Vexta brand. I managed to get a data sheet for this motor online a few months ago from a university web site in Wisconsin.

The resistance for each center-tapped winding is listed as 20 Ohms.
The inductance of each winding is listed as 32 mH.

I took a resistance measurement of the windings. They are 40 Ohms from each winding's end to end, but 20 Ohms from center tap to each end. This makes me think that the inductance specification on the data sheet would refer to the inductance from center tap to each end also.

I don't have an inductance meter, and I would like the total inductance of each winding from end to end. Inductors in series are additive. That way the inductance from end to end would be 64 mH. However if the windings are wound on a common core, the inductance would be 128 mH because the total inductance is proportional to the square of the number of turns.

Or, would the inductance be somewhere in between the two figure depending on how closely coupled the two halves of each winding are?

Does anyone have any insight?

Thanks,
Bob

[k7elp60]

Bob,
You could measure the inductance in a round about way.
Create a constant current source and charge them up with the constant current source, while monitoring the voltage and the time, then do the calculation.

[MrAl]

Hi Bob,


There are a number of ways to measure inductance, but they all depend on what
test equipment you have on hand. So, what kind of test equipment do you have
on hand or can you borrow?