The Mendocino motor is a solar-powered magnetically suspended electric motor. It floats in the air with virtually no friction thanks to the magnetic suspension. The solar cells on the outside of the motor drive solenoids inside the motor, which, combined with another magnet in the lower frame, allow for zero-friction rotation around the motor’s axis.
image/text credit: Wolfram Glatthar
The rotor block has two sets of windings and a solar cell attached to each side. The shaft is positioned horizontally and has a magnet at each end. The magnets on the shaft provide levitation by repelling magnets in a base under the motor. This air friction bearing is required because a Mendocino motor uses Lorentz force without iron core.
There is an additional magnet that sits under the rotor block and provides a magnetic field for the rotor. Other motors hide the base magnet in a tube.When light strikes one of the solar cells, it generates an electric current thus energizing one of the rotor windings. This produces a magnetic field, which interacts with the field of the magnet under the rotor.
This interaction causes the rotor to turn. As the rotor rotates, the next solar cell moves into the light and energizes the second winding, creating a current in an opposite direction to the first, thus maintaining the rotation. This process repeats as the motor spins.