Stepper motor as generator

Thread Starter

wayneh

Joined Sep 9, 2010
17,495
I just scavenged some parts from a printer I was throwing out and got to wondering about the stepper motor, which was the paper feed controller. It has 4 wires, so two coils.

Lots of hobbyists use stepper motors for generators because they produce more voltage at lower RPM than a typical DC motor. All the schematics I see use two full bridge rectifiers, one for each coil.

Why? Shouldn’t the two coils always be producing signals that oppose each other? (Isn’t that how you drive one?) It seems to me you could wire the coils in series and just use a single rectifier bridge. Of course you have to get the polarity right.

I suspect I’m missing some crucial property of these motors. Never played with one.
 
Top