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2D Rotating electrical machine, calculating torque

Posted 9 oct. 2014, 12:22 UTC−4 Low-Frequency Electromagnetics, Fluid & Heat Version 4.4 5 Replies

José Silva
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Hello all

I'm studying a machine with permanent magnets in the stator and a solid iron rotor(no coils).
i already have the magnetic field, is there a way to extract the torque felt by the rotor?

Best regards
José Silva
5 Replies Last Post 11 oct. 2014, 10:26 UTC−4
Philippe Masson
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Posted: 1 decade ago 9 oct. 2014, 13:22 UTC−4
I am not sure how you can have a rotating machine with permanent magnets at the stator and no winding at the rotor... Or maybe I misunderstood your description of the system.

COMSOL allows you calculate the forces and torque on components when you set up the problem. Add a "force calculation" in the physics (Magnetic Fields) tree and select the components on which you need the forces/torque calculated. The results are available as global variables and displayed during post-processing (Derived Values).

For forces on iron, the method used should be based on virtual work. If you want to implement the torque calculation yourself, you can integrate a function based on Maxwell's tensor over a section of the air gap. You should be able to find plenty of papers describing how to do it.

Hope it helps.
Best,
Philippe
I am not sure how you can have a rotating machine with permanent magnets at the stator and no winding at the rotor... Or maybe I misunderstood your description of the system. COMSOL allows you calculate the forces and torque on components when you set up the problem. Add a "force calculation" in the physics (Magnetic Fields) tree and select the components on which you need the forces/torque calculated. The results are available as global variables and displayed during post-processing (Derived Values). For forces on iron, the method used should be based on virtual work. If you want to implement the torque calculation yourself, you can integrate a function based on Maxwell's tensor over a section of the air gap. You should be able to find plenty of papers describing how to do it. Hope it helps. Best, Philippe
José Silva
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Posted: 1 decade ago 9 oct. 2014, 14:37 UTC−4
It has a coil, but for now, i haven't connected it to anything yet so no current.
for now i just need to know, having the speed rotation and the magnetic flux the torque the rotor is under.

Thanks for the tip I'll give it a try.
It has a coil, but for now, i haven't connected it to anything yet so no current. for now i just need to know, having the speed rotation and the magnetic flux the torque the rotor is under. Thanks for the tip I'll give it a try.
Nirmal Paudel COMSOL Employee

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Posted: 1 decade ago 10 oct. 2014, 20:40 UTC−4
The following Magnetic Gear example shows how to do the torque calculation on two rotors/stator. Hope this will be useful.
www.comsol.com/model/magnetic-gear-in-2d-14583

Nirmal Paudel
--------------------------
COMSOL Employee
USA
The following Magnetic Gear example shows how to do the torque calculation on two rotors/stator. Hope this will be useful. http://www.comsol.com/model/magnetic-gear-in-2d-14583 Nirmal Paudel -------------------------- COMSOL Employee USA
Zhou Lu
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Posted: 1 decade ago 11 oct. 2014, 02:46 UTC−4
Hi,

I am getting the following error:
Log of negative
Function: log
Failed to evaluate variable
Variable: mod1.St, Defined as: ((mod1.p>=mod1.pea)*((cs-mod1.c)*(log((mod1.p/mod1.pea))*(exp(((-Ea)/(Rg*mod1.T)))*ka))))
Failed to evaluate expression
Expression: d((2*mod1.St*test(mod1.c)*pi*r)*(dvol),{test0})

Do you know how to fix this problem?

Thanks in advance for the comments
Hi, I am getting the following error: Log of negative Function: log Failed to evaluate variable Variable: mod1.St, Defined as: ((mod1.p>=mod1.pea)*((cs-mod1.c)*(log((mod1.p/mod1.pea))*(exp(((-Ea)/(Rg*mod1.T)))*ka)))) Failed to evaluate expression Expression: d((2*mod1.St*test(mod1.c)*pi*r)*(dvol),{test0}) Do you know how to fix this problem? Thanks in advance for the comments
Nirmal Paudel COMSOL Employee

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Posted: 1 decade ago 11 oct. 2014, 10:26 UTC−4
We encourage you to post your questions on the related thread. Or create the new thread if needed.

Nirmal Paudel
--------------------------
COMSOL Employee
USA
We encourage you to post your questions on the related thread. Or create the new thread if needed. Nirmal Paudel -------------------------- COMSOL Employee USA

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