Question

What is cogging? How to eliminate cogging?

Answer 1

The number of stator slots are never made equal to the rotor or have an integral ratio. It can also be reduced by using the skewed rotor. Cogging and Crawling are less eminent in wound rotor motors because of the higher starting torques.

Answer 2

Answer:

• Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet machine. It is also known as detent or 'no-current' torque
• The most effective way to reduce cogging torque is skewing of stator slots or rotor poles. It means skewing of one side of stator (rotor) core by few degrees in according to the other side of core (Fig. 7). The skewing allows to eliminate the cogging torque or to reduce it to minimum