Method for balancing cogging torque of an electrical machine with permanent magnet rotor and slotted stator, and relevant electrical machine with balanced cogging torque

A method for balancing a total cogging torque of an electrical machine with a permanent magnet rotor and slotted stator to a zero, wherein the stator has S number of slots and the rotor has P number of magnetic poles, and wherein the ratio of the number of slots S and the number of magnetic poles P is an integer Q, wherein the rotor and the stator comprise two magnetically equal coaxial parts, wherein the parts of the rotor or the stator are shifted on the rotational axis in relation to each other by an angle Θs, where Θs=180°/S, wherein an actual angular width of magnetic pole shoes of the rotor is found from an equation Θm=k·Θme, where k is a correction factor taking account of edge effects with value 0.8 . . . 1.1, and Θme is effective angular width of the magnetic pole shoes of the rotor, which is determined from an equation Θme=(Q−1/2)ΘSp, where ΘSp is stator pitch angle and where ΘSp=360°/S, and Q is equal to 1 or 2.

An electrical machine with permanent magnet rotor and slotted stator with a zero total balanced cogging torque, wherein the stator has S number of slots and the rotor has P number of magnetic poles, and wherein the ratio of the number of slots S and the number of magnetic poles P is an integer Q, wherein the rotor and stator comprise two magnetically equal coaxial parts, wherein the parts of rotor or stator are shifted on a rotational axis in relation to each other by angle Θs, where Θs=180°/S, wherein the actual angular width of magnetic pole shoes of the rotor Θm corresponds to an equation Θm=k·Θme, where k is a correction factor taking account of edge effects with value 0.8 . . . 1.1 and, Θme is effective angular width of the magnetic pole shoes of the rotor, which corresponds to the equation Θme=(Q−1/2)ΘSp, where ΘSp is stator pitch angle and ΘSp=360°/S, and Q is equal to 1 or 2.