Torque ripple is an effect seen in many

electric motor An electric motor is a 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 electromagnetic coil, wire winding to gene ...

designs, referring to a periodic increase or decrease in output

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

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 magnet A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable pro ...

" due to slight asymmetries in the

magnetic field A magnetic field (sometimes called B-field) is a physical 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 ...

generated by the motor windings, which causes variations in the

reluctance Magnetic reluctance, or magnetic resistance, is a concept used in the analysis of magnetic circuits. It is defined as the ratio of magnetomotive force (mmf) to magnetic flux. It represents the opposition to magnetic flux, and depends on the ...

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.

External links

*{{Commonscatinline, Torque ripples Electric motors Torsional vibration Ripple