Manatee e-NVH software enables to quickly define several sets at any position of rotor or stator notches (also called auxiliary or dummy slots). Notches consist in removing magnetic materials at the bore radius.
In synchronous machines, notches can be added along D or Q axis. Notches can be evenly distributed or unevenly distributed. Besides, several notch geometries are available: rectangular, polar, circular, trapezoidal and user defined with DXF import.
Adding a new piece of material along stator or rotor bore radius instead of removing some material is also possible in Manatee by using the concept of “keys”. The material of keys can be user-defined, it can be magnetic materials but not Permanent Magnets. For instance, keys can be used to add pieces of Soft Magnetic Composite (SMC) inside the electrical machine.
Notching can be used by Electrical Engineers to modulate differently the airgap permeance and reduce cogging torque, torque ripple and or magnetic noise and vibrations. If properly sized, it can indeed artifically increase the number of slots and can therefore shift some e-NVH resonances. Notching can be applied to both rotor and stator, whatever the electrical machine type. It is also called circumferential slits, auxiliary slots or dummy slots.
Simulation is advised to properly size the notch as the optimal notch shape minimizing both magnetic noise and vibrations and torque ripple can depend on the operating point.