For my Power Electronics Lab, this week, we built the three-phase drive for an induction motor. Induction motors are pretty damn cool, and while I think they are the hardest motor to understand, they certainly have the most interesting torque speed curve.
And induction motor is basically a series of coils that you run current through one by one. The coils are the stator, they stay still. As the current moves from one coil to the next, you induce a current in the rotor, which then induces a force on the rotor. So just by swapping the current in and out of the coils on the stator, you get motion. No brushes, no fancy magnets, nothing.
The drive circuitry is pretty cool, at least for discrete components. You build a “finite-state machine”, which basically means you have it switch through states. Each state corresponds to certain switches that turn on and off the coils in the stator.
Anyway, giant success last night when after long hours of trying to debug my poor, noisy drive circuit I finally got the thing spinning!