Learning Forum

[s3740222]

I want to know how to calculate cogging force in ansys maxwell 3d for linear generator. Is it the magnet force or the force along either x, y or z direction. Confused

[s3740222]

Can anybody help pls

[NKC]

Hi Cogging force is always measured with stator winding unexcited. (I am calling the armature with winding coils as stator and the slider with magnets as slider)
Since you are working on a linear machine, it is the amount of force it takes to move the slider in liner direction parallel to stator.
Of course, you may need to run parametric analysis with different positions of the slider to find the cogging force at different positions.
So, depending the way your model is setup, Cogging force will be along either of the direction of motion of your slider(with magnets).

Regards
Navya

[s3740222]

Thanks for your reply. That means , the moving force along the Y direction is the cogging force but as per the transient analysis, everything which comes under BAND will tend to experience force. and cogging force should exist in x and z direction if the translator is moving in y direction. Translator is moving due to band applied to it and this is experiencing force which is responsible for EMF, given as BiL. Please correct me as this been long i am struggling to sort this out.
Thanks again.

[NKC]

Hi Lets think about it in practical application. If I give you a linear motor/generator and a force measuring instrument what will you do for measuring cogging force?
You will be moving the shaft (attached to the slider) and measure the corresponding force experienced at different positions of the slider when it is moved in the linear direction (Y direction in your setup).
This is because, though the slider will be experiencing forces in other directions it is restricted to move in those direction by the construction itself. So the only freedom of movement and resultant slider direction is in Y direction.
So if you assign the force parameter to the stator and assigning a translation motion to the band (for slider) and analyze, then you can plot for Force w.r.t. moving position which is the cogging force.
Additional Suggestions
Perform 2D simulation if your model is symmetric - in this case the force direction will be along x direction.
Assign additional dummy bands for better meshing (important for accurate results).
Define a slow translation motion and lower time step in setup.
Hope this will answer your query.

Thanks
Navya

[s3740222]

Thankyou so so much for your reply. I should assign force parameter to stator and should move the translator and the force experienced by the stator will be cogging. But my understanding says that though we have restricted the translator to move inside the band but this will experience force in x and z direction. And this force in x and z direction should be termed as cogging force. Because if we talk about practical application then undoubtedly this force in x and z direction will create interaction with stator.
Thanks again for your additional suggestion. I will try to do this in 2d.
Thanks Again.