Glossary of Motor Terms

Slotless rotor

A rotor where the winding has been fixed to a cylindrical iron core without using slots. This produces extremely low cogging torque. In a slotless construction the torque is exerted directly on the wires (the coil pieces) due to BLI law and Fleming's left-hand rule. Rare-earth or large Alnico magnets are needed in order to get sufficient flux because of the long gap between the rotor core and the pole shoes.

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