Cogging torque in permanent magnet motors
Introduction
Cogging is an undesirable characteristic of some permanent magnet motor designs. It's also known in stepper motors as 'detent' or 'no current' torque.
Cogging torque is generated when the sides of the rotor teeth line up with the sides of the stator teeth within the motor. We can think of permanent motors as having a magnetic circuit as well as an electrical circuit, and when the rotor and stator teeth are aligned the 'resistance' in the magnetic circuit is at its lowest.
Cogging Effects
Therefore when you ro…