Torque ripple is an effect seen in many

electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate f ...

designs, referring to a periodic increase or decrease in output

torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...

as the motor shaft rotates. It is measured as the difference in maximum and minimum torque over one complete revolution, generally expressed as a percentage.

Examples

A common example is "

cogging torque Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a permanent magnet machine. It is also known as ''detent'' or ''no-current torque''. This torque is positio ...

" due to slight asymmetries in the

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

generated by the motor windings, which causes variations in the reluctance depending on the rotor position. This effect can be reduced by careful selection of the winding layout of the motor, or through the use of realtime controls to the power delivery.

References

"Torque ripple"
Emetor Electric motors Torsional vibration