Cogging torque analysis based on energy approach in surface-mounted PM machines

The problem of cogging torques produced in permanent magnet (PM) machines is crucial. Motor and generator applications require the machines to produce a smooth torque with very low cogging torque components. This paper presents a simplified energy approach for a model of the machine with PM located on the rotor surface. Briefly, analytical co-energy formulas are applied in order to determine the cogging torque harmonics and show methods of their reduction. Additionally, the analysis of cogging torque for machines with the poles composed of segmented PM are presented.