Electric machine having asymmetric magnetic pole shape for torque ripple reduction

An electric machine having a stator and a rotor or mover that is opposite to the stator and is moved relative to the stator,

• wherein a plurality of magnetic poles is periodically arranged at a predetermined interval on the stator, or a plurality of magnetic poles is periodically arranged at a predetermined interval on the rotor or mover,
• wherein the plurality of magnetic poles is manufactured in an asymmetric shape to realize an asymmetric magnetic-pole arrangement for the purpose of reducing a torque ripple,
• wherein the plurality of magnetic poles comprises a periodic arrangement of an asymmetric permanent magnet having a first asymmetric shape and an asymmetric core having a second asymmetric shape,
• wherein the outer circumferential surface of the second asymmetric shape is identical to the outer circumferential surface of the first asymmetric shape,
• wherein the asymmetry of each asymmetric permanent magnet is defined by a first edge of each asymmetric permanent magnet having a different shape from every other edge of the asymmetric permanent magnet,
• wherein the asymmetric permanent magnet has a layer structure comprising asymmetric permanent magnets stacked in two or more layers and arranged in a direction perpendicular to a surface of a core,
• wherein the asymmetric permanent magnets are asymmetrically arranged such that first edges of the asymmetric permanent magnets are oriented in opposing directions by layer and are oriented in same directions in a same layer, and
• wherein the asymmetric permanent magnets are asymmetrically arranged such that a first torque ripple of a first asymmetric permanent magnet located in a first layer of the layer structure and a second torque ripple of a second asymmetric permanent magnets located in a second layer of the layer structure have a same or similar magnitude and a phase difference of 180 degrees.