Cylindrical motor

A cylindrical type rotor with a simple outer shape is the principle definition. It is typically found in eddy current motors using soft steel, hysteresis motors using weak permanent magnets, and brushless motors using a bonded magnet. Many squirrel-cage induction motors have slot openings, but this type is cylindrical in a broad sense. A representative example of a non-cylindrical type is the convex pole type motor. Some motors appear to be cylindrical but actually have a salient pole function because of the internal structure.
The torque for this type of rotor can be expressed by a surface integral or the Stieltjes-type volume integral. The equation below shows the two integral forms of the torque equation generated in a cylindrical rotor.