Cogging Torque

Cogging Torque

Cogging torque describes the interaction of rotor magnets acting on stator poles

Spin motor shaft with hand pulsation felt during the process is called cogging torque

When magnet in the motor passes stator teeth reluctance experienced by magnet under slot opening causes varying reluctance which contributes to cogging torque

Narrow the slot opening means smaller the cogging torque, if there is no slot opening, cogging torque will be zero

As a thumb rule slot opening must be at least two to three times the covered diameter of the wires

Radial dimension of pole shoe also plays a role in cogging torque

If radial shoe dimension is too small, shoe tip become saturated and added to reluctance which contributes to cogging torque

Each magnet in rotor contributes to cogging torque therefore relation between number of stator slot and magnet pole influences the cogging torque.