It can find several researches on cogging torque analysis and reduction in permanent magnet machines. A clear reason for such efforts is that cogging effects contribute to the total loaded torque ripple, and hence, cogging reduction will usually results in smoother loaded torque profile. ٍExcluding the effects on the total loaded torque ripple, is there any special reason that makes cogging torque important?
Does the level of cogging torque importance differ for different applications (e.g. vehicles, industrial, wind energy, etc)?
Thanks
Hello Amin,
In addition to torque ripple when the machine is loaded, cogging is also a factor of noise. For low speed operations, this torque ripple is really undesirable as you can have jerkiness, high torque ripple (can be damageable for the output of a motor), and speed ripple (not great for control strategies). Think about positionning also, cogging torque is associated with "preferred position of magnetization" of the rotor facing the stator. If you want to position your motor in an unstable position, it can take you too much current and also unnecessary control of the unstable position. At higher speeds, the moment of inertia filters out the effect of cogging torque.
Apart from torque ripple, it is difficult to start a motor with high cogging torque. Additional measures are required in such a case. Of course, cogging torque importance is different in different applications. Usually, if the application is less sensitive to torque ripple, higher cogging torque is permitted e.g. vacuum cleaner, fan
Hello respect Amin Nobahari
Cogging torque result due to interaction of slots and Permanent Magnet (PM). Despite of the torque ripples, cogging torque results in noise and vibration there for it's level differ for different application.
For example: For robotic the level of cogging torque must be least to avoid vibration that results in vibration whereas is it's level must be different for electric vehicle to avoid excessive noise. Similarly for industrial and other applications, the level of cogging torque varies.
Regard:
Wasiq Ullah
Comsats University Islamabad, Abbottabad Campus
Sometimes for wind turbine generators the “cogging torque” parameter is indicated in the catalog. See for example this catalog http://www.alxion.com/wp-content/uploads/2011/10/82.pdf. Probably generator cogging torque affects starting torque of wind turbine
1. I can not find a good paper on the topic "effect of electric motor torque ripple on reliability and loss in the gearbox". If someone met such papers, please recommend some links.
2. If the universal (brush) motor is powered by a single-phase grid, then its torque ripple of at least 200%. However, universal (brush) motors are very often used in household appliances. Is it actual to reduce the torque ripple for such applications as electric tools (miter saws, drills, angular grinder), washing machine, blender etc?
Cogging torque can break the rotor of any electrical machine, leads the rotor is difficult to be rotated. Even the r
Cogging torque in any of electric machine structure is difficult to be rotated. Even the rotor can be rotated, it will geberate vubration
In wind turbine, cogging torque is important to start the wind turbine rotation in low wind speed
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