Fast Design of Asymmetrical Permanent Magnet Synchronous Machines That Minimize Pulsating Torque
Torque pulsations in Permanent Magnet Synchronous Machines are mainly created by interaction between the permanent magnets and stator teeth, harmonics in the stator current, steel saturation and partial magnet demagnetization. As a consequence of torque ripple, there are increased noise and vibrations. To overcome them, some methods for reducing pulsating torque include controlled-asymmetry. The strategy seeks for compensate or cancel out spatial harmonics of flux density in the air gap. This work proposes an analytical method based upon sub-domain model that allows techniques such as stator teeth pairing, slot opening shift, nonuniform teeth, tangential shift of magnets, different magnet widths, among others, to be utilized and quickly analyzed. Since asymmetries introduce several degrees of freedom, the design of Permanent Magnet Synchronous Machines can be accelerated by means of analytical-based tools. The proposed model is validated with Finite Element method.