Reducing cogging torque
In electric motors, the magnets of the rotor and the slots of the stator interact. This interaction results in the so called the cogging torque. It is also called detent or “no-current” torque. Generally speaking, the cogging torque is undesirable because it causes jerkiness and speed ripple, especially at low speed. It is worth mentioning that a slotless machine is cogging torque free.
There are numerous techniques to reduce the cogging torque. EMS can be instrumental in investigating such technique without the need to build prototypes. For instance, the designer can distort the stator and/or the magnets virtually in SolidWorks or Inventor and run EMS for various distortion angles and study the effect on the torque. Similarly, one can consider various current forms or play on the number of slots. The parameterization feature of EMS makes this task fast and efficient.