Analytical approach to cogging torque calculation in PM brushless motors

The paper discusses the approach to analytical calculation of the cogging torque in PM brushless motors. Magnetic field energy in the air gap has been used to calculate the torque. Two equations have been derived: with the PM width taken into account, and simplified equation, i.e., without the effect of the finite width of the PM. The effect of eccentricity has been included too. Analytical results have been compared with laboratory test results.