Question of Demanganization Option for Simulation
Dear all,
I have an IPM demanganization question for Flux simulation.
When I choose the option of “Taking into account demagnetization during solving process”, I get the torque result like figure below. (The parameter is only for test.)
However, I cancel the option of “Taking into account demagnetization during solving process”. I get the torque result like demagnetization status. Does anyone know what is the reason of this situation? Why the torque sometimes get the minus result? I’ve attached the model. Thank you!
Answers
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Hi Allen,
Related to the option „Taking into account demagnetization during solving process” in the definition of the magnets material you set o wrong value for the Maximal relative permeability. I know that for NDFEB_N45H magnets is 165, so the value that you set is too high.
In the definition of the mechanical set ROTOR you impose the speed of the rotor, for the cases where the electromagnetic torque is negative the motor is not capable of generating enough torque at that speed with the imposed value of the maximal stator current.
Best regards,
Alexandru
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Hello Allen,
From what I see you are using sm2co17 magnets; these magnets have a coercive field greater than the one you set. You can use a value of 765 kA/m, so you have to set 765000 in the apposite field, that is the Hcb value that you can find in the magnet datasheet.
Furthermore, I suggest you to choose the static computation as transient initialization; you can set it from Application --> Edit current application --> transient initialization.
The results are consistent with these settings, please let me know if you still have any doubts on this topic.
Best regards,
Letizia F.
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Hi Allen,
Related to the option „Taking into account demagnetization during solving process” in the definition of the magnets material you set o wrong value for the Maximal relative permeability. I know that for NDFEB_N45H magnets is 165, so the value that you set is too high.
In the definition of the mechanical set ROTOR you impose the speed of the rotor, for the cases where the electromagnetic torque is negative the motor is not capable of generating enough torque at that speed with the imposed value of the maximal stator current.
Best regards,
Alexandru
Hello Alexandru,
Thank you for your fast reply.
I tried the value of Maximal relative permeability with 165 and get the results consistent with these settings.
However, I'm just curious why I try to set a very high value of Maximal relative permeability (means a very steep slope?) like the blue line of figure below will get the opposite status?
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Letizia Ferrara_21767 said:
Hello Allen,
From what I see you are using sm2co17 magnets; these magnets have a coercive field greater than the one you set. You can use a value of 765 kA/m, so you have to set 765000 in the apposite field, that is the Hcb value that you can find in the magnet datasheet.
Furthermore, I suggest you to choose the static computation as transient initialization; you can set it from Application --> Edit current application --> transient initialization.
The results are consistent with these settings, please let me know if you still have any doubts on this topic.
Best regards,
Letizia F.
Hello Letizia,
Thank you for your fast reply. I tried those settings and get the reasonable results and still have a question of Maximal relative permeability for simulation results. Thank you!
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Hello Allen,
The maximum relative permeability is the slope of the curve that you can see in the following picture.
In this case a very high value is used just as example, but this value affects a bit the results, so to have an appropriate value you have to see the demagnetization curves (at different temperatures) provided by the magnet supplier and choose the right one.
In the model that you shared, also using a quasi-stright line we can see a partial magnets demagnetization.
I recommend increasing the thickness (and/or eventually decreasing the length) of your magnets to avoid this effect and improve motor performance.
Best regards,
Letizia
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Letizia Ferrara_21767 said:
Hello Allen,
The maximum relative permeability is the slope of the curve that you can see in the following picture.
In this case a very high value is used just as example, but this value affects a bit the results, so to have an appropriate value you have to see the demagnetization curves (at different temperatures) provided by the magnet supplier and choose the right one.
In the model that you shared, also using a quasi-stright line we can see a partial magnets demagnetization.I recommend increasing the thickness (and/or eventually decreasing the length) of your magnets to avoid this effect and improve motor performance.
Best regards,
Letizia
Hello Letizia,
I see, thank you!
Allen
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Altair Employee