Stepper motors move in discrete steps. A stepper motor can take one of three types:
- Permanent magnet (PM) stepper motor
- Variable reluctance (VR) stepper motor
- Hybrid stepper motor
Permanent Magnet Stepper Motor
These use a PM rotor + EM stator.
Four phase PM stepper motor:
- Through a sequence of turning on and off each coil, we can create “stepping” motion
- This operation makes step angle (Can we make ?)
Variable Reluctance Stepper Motor
We can actually do this without permanent magnet!
- Using a principle called reluctance torque
- A tendency of an iron bar to align itself with magnetic field
- The rotor is attracted to the nearest active pole pair
For VR stepper motors, we have
Switching sequence for (three phases of) coils:
