A fan that plugs into a wall outlet is likely an AC mot […]
A fan that plugs into a wall outlet is likely an AC motor. They are simple to build, no electronics necessary. Small 120Vac (or 240Vac for Europe) fan motors are often just capacitor run AC motors or split phase AC motors. Really small AC fans use shaded pole motors.
Types of Single Phase Induction Motor | Split Phase Capacitor Start Run Shaded Pole
Now if you mean a computer fan, well, the answer is more complicated. They require DC voltage to run, but the motor itself is really a 3 phase AC motor. The electronics converts DC into a 3 phase AC drive for the motor.
We call these by the rather misleading name, DC Brushless Motor. Because there are no brushes, and they require DC. The rotor has permanent magnets in it. The stator is in the middle and looks a lot like the center rotor of a DC brushed motor, but it doesn’t turn. The rotor is a shell around it with magnets inside it.
A DC brushed motor is really a 3 phase AC motor with a mechanical commutator to convert incoming DC into 3 phase AC. Then the part with the windings can be the nonmoving stator. This is great, because the fastest wearing parts in a DC brushed motor are the brushes and commutator.
More and more motors are being made this way with 3 phase motors driven by an electronic drive that uses DC power. Washing machines, dryers, dishwashers, electric cars and bicycles, etc. I have an 800W motor on my CNC machine for the cutting head, it is a 3 phase AC motor that connects to a box with electronics that is called a VFD for Variable Frequency Drive. It generates 3 phase AC at the frequency required to spin the motor at a specific frequency.
Electric radio controlled airplanes and cars use the same motors. They are compact and high power.
Hard drive, floppy drive, and CDRom drive motors are 3 phase motors with electronics to drive them, and would be classed as DC Brushless Motors.
The rotor may be inside the stator, or in a shell outside of it. It may use permanent magnets, or it may use a squirrel cage rotor that is always slipping a bit slower than the magnetic field rotation.