2 Phase AC Motor Controller


For the sake of playing with this I took a 2 phase stepper motor and commoned two of the wires to take the place of the motor for me, I wired it as follows:

The motor that I used was a disk drive stepper, 12v, 1.8 deg's/step, .08A {block motor} using my trusty scope I found that I 5 uF capacitor gave the desired 90 deg's of phase shift required.

I took to reverse engineering a motor controller from the local pulp mill, the first thing that interested me was a darlington arrangment used with the opto isolators, thusly:

Here is the schematic from the reverse engineered controller, I'v left out the other controll circuitry:
the controller was a [Jordan Controlls Inc 50-C-019338 REV 1]

And finally the circuit that I put togethor:

There are a few notes about doing this with 120V or higher motors..
* I have left out the snubbers, at this voltage and current there isn't going to be any problems with power spikes killing the triacs
* I have left out a protecting resistor that should go in series with the 5 uF capicator, this protects the triacs from discharge currents if both triacs are turned on.

A note for triggering triacs:

for calculating the gate resistor, use the following formulaeulas:
R = V/100mA where V is the source for triggering the triac.
P = V^2/R as you might quickly note, its desirable to have a low driving voltage...


There are no spelling erors in this, my room is declared as a seperete country in wich the rules of spelling are difrent. I don't take responceability for you getting in trouble for taking apart other peoples computers for partz. I do make mistakes, and if there is one in a schematic i have provided you have my permission to write me a mean letter.


Back, need more be said?


Dan Williams, Member of planet earth (currently)