Permanent magnet electric machine and permanent magnet with linearly increasing air gap for an electric machine

摘要

The disclosure relates to an electric machine with a permanent magnet rotor, where permanent magnets have been fitted on an outer surface of a cylindrical rotor, and relates to a permanent magnet. The permanent magnets forming the electric machine's rotor pole are shaped so that the electric machine's air gap is substantially constant in a middle of the pole, and the air gap increases in an essentially straightforward manner when moving towards the edge of the pole. The permanent magnet is of an even thickness in the middle, and becomes thinner towards the edges. This can result in a decrease in the torque ripple and cogging torque of an electric machine.