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How to calculate the force on a permanent magnet due to surrounding winding current
Posted Mar 4, 2015, 12:56 p.m. EST Low-Frequency Electromagnetics 1 Reply
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This should be a simple model, but I am very new to comsol and cannot find the relevant tutorials.
I have a permanent magnet, then an air gap, then a coil going around the permanent magnet.
To model this I have created three rectangular geometries next to each other. The furthest left will be the permanent magnet, the middle is air, and the furthest right is copper. I have added an axial symmetry to the left boundary of the magnet. This means the copper surrounds the magnet with an air gap between.
I have added an external current to the copper domain, with a current density in the direction phi. This means the current goes around the copper ring. This simulates a multi winding coil with a current going through it.
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My Question
How do I turn the furthest left rectangle into a permanent magnet, and how do I calculate the force on it? Eventually I want to move the magnet up and down into different positions and calculate the force as a function of distance. But for now just calculating the force on the magnet from the electric field generated by the coil is enough.
I have a permanent magnet, then an air gap, then a coil going around the permanent magnet.
To model this I have created three rectangular geometries next to each other. The furthest left will be the permanent magnet, the middle is air, and the furthest right is copper. I have added an axial symmetry to the left boundary of the magnet. This means the copper surrounds the magnet with an air gap between.
I have added an external current to the copper domain, with a current density in the direction phi. This means the current goes around the copper ring. This simulates a multi winding coil with a current going through it.
------------------------------------------------------------
My Question
How do I turn the furthest left rectangle into a permanent magnet, and how do I calculate the force on it? Eventually I want to move the magnet up and down into different positions and calculate the force as a function of distance. But for now just calculating the force on the magnet from the electric field generated by the coil is enough.
1 Reply Last Post Mar 4, 2015, 4:24 p.m. EST
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Posted:
10 years ago
Craig,
let's assume you are using the mf-approximation for your model.
- Assign a new Ampere's law to the magnet domain and set some magnetization or remanent flux density.
- Add a force calculation to the magnet domain
- Don't forget you need to have an air domain around the assembly with sufficient size to allow the fields to fill the space around the setup. The air box has to be large enough to avoid deformations of the field. I you want to keep it small you can try infinite element domains around your model.
You will find that adding the force calculation makes the respective force variables available in the post processing.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
let's assume you are using the mf-approximation for your model.
- Assign a new Ampere's law to the magnet domain and set some magnetization or remanent flux density.
- Add a force calculation to the magnet domain
- Don't forget you need to have an air domain around the assembly with sufficient size to allow the fields to fill the space around the setup. The air box has to be large enough to avoid deformations of the field. I you want to keep it small you can try infinite element domains around your model.
You will find that adding the force calculation makes the respective force variables available in the post processing.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com