Calculation problem of Solid conductors with capacitors

Yerai Moreno Lafuente
Yerai Moreno Lafuente Altair Community Member
edited April 2022 in Community Q&A

Hello,

I am working with this circuit in flux, to obtain the impedance in a frequency range.

image

However, I also need the resistance and inductance values, and when comparing the resistance obtained from the joule losses with the real part of the impedance of each solid conductor they are not matching. The same happens with the inductance obtained doing flux/current and the inductance obtained from the imaginary part of the impedance.

image

It is something not working properly with capacitors?

Moreover, when I use the obtained Resistance and inductance values and solve the circuit analytically, it does not match with the source impedance.

image

I put the model attached if you want to take look of how I have defined all and if you see any mistake, I would be very grateful.

Thank you,

Yerai Moreno

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Best Answer

  • Farid zidat_20516
    Farid zidat_20516
    Altair Employee
    edited April 2022 Answer ✓

    Yes, the sum of Z1 and Z2 matches with the impedance seen by the source in the case without the capacitor.

    image

    Thanks Yerai!

     

    So as you can see, adding Z3 without represente it in the circuit is not true, because the capacitance will add reactive energy that will have an impact on the two solid conductors. That's why you had these wrong results.

    The current through the solid conductors in series is not the same with or without the capacitance.

    Regards 

Answers

  • Farid zidat_20516
    Farid zidat_20516
    Altair Employee
    edited April 2022

    Hello Yerai;

     

    There a lot of points that we should take care:

    1- The solid conductors contains Joule losses, and also an active power transfered from the coil 1 to coil 2 and vis versa. Because the current in coil 1 will induce Eddy current in coil 2 and the same from coil 2 on 1. So to compute the impedance of Coil 1 and Coil 2, you should consider Active power in case you want to compare it for the total impedance seen from the source.

     

    2- I suggest you to compute Z1 the impedance for Coil 1, Z2, the impedance for coil 2 and Z3 the impedance for capacitor. For each component, compute Active power and reactive power, and then compute the real part and imaginary part from them. Compute the equivalent Z and compare it to the one you have from the circuit. You should obtain the same thing.

     

    Regards 

  • Yerai Moreno Lafuente
    Yerai Moreno Lafuente Altair Community Member
    edited April 2022

    Hello Yerai;

     

    There a lot of points that we should take care:

    1- The solid conductors contains Joule losses, and also an active power transfered from the coil 1 to coil 2 and vis versa. Because the current in coil 1 will induce Eddy current in coil 2 and the same from coil 2 on 1. So to compute the impedance of Coil 1 and Coil 2, you should consider Active power in case you want to compare it for the total impedance seen from the source.

     

    2- I suggest you to compute Z1 the impedance for Coil 1, Z2, the impedance for coil 2 and Z3 the impedance for capacitor. For each component, compute Active power and reactive power, and then compute the real part and imaginary part from them. Compute the equivalent Z and compare it to the one you have from the circuit. You should obtain the same thing.

     

    Regards 

    Thank you very much! Using active and reactive power it matches perfectly.

  • Yerai Moreno Lafuente
    Yerai Moreno Lafuente Altair Community Member
    edited April 2022

    Hello Yerai;

     

    There a lot of points that we should take care:

    1- The solid conductors contains Joule losses, and also an active power transfered from the coil 1 to coil 2 and vis versa. Because the current in coil 1 will induce Eddy current in coil 2 and the same from coil 2 on 1. So to compute the impedance of Coil 1 and Coil 2, you should consider Active power in case you want to compare it for the total impedance seen from the source.

     

    2- I suggest you to compute Z1 the impedance for Coil 1, Z2, the impedance for coil 2 and Z3 the impedance for capacitor. For each component, compute Active power and reactive power, and then compute the real part and imaginary part from them. Compute the equivalent Z and compare it to the one you have from the circuit. You should obtain the same thing.

     

    Regards 

    Hello Farid,

    Your solution matched with the Impedance seen by the source.

    However, I did a new comparison and it is a bit confusing.

    I simulated the same conductors, but without including any capacitor.

    image

    Then, I obtain the Z1 and Z2 of the solid conductors as you mentioned with active and reactive power.

    After, I define Z3=1./(2*pi*Freq*1i*1e-5).

    Finally, I obtain the total impedance as in the previous case:
    Zan=((Z1.*Z3)./(Z1+Z3))+Z2;

    image

    In theory, I think both ways should match with each other isn't it? or There is a different current distribution that changes the behaviour of the solid conductors when adding the capacitor in FEM?

    Thank you very much

  • Farid zidat_20516
    Farid zidat_20516
    Altair Employee
    edited April 2022

    Hello Yerai;

     

    Can you first compare the impedance seen from the source to the one you computed from Z1 and Z2 ? Both in the case without the capacitor, did they match ?

     

    Thanks 

  • Yerai Moreno Lafuente
    Yerai Moreno Lafuente Altair Community Member
    edited April 2022

    Hello Yerai;

     

    Can you first compare the impedance seen from the source to the one you computed from Z1 and Z2 ? Both in the case without the capacitor, did they match ?

     

    Thanks 

    Yes, the sum of Z1 and Z2 matches with the impedance seen by the source in the case without the capacitor.

    image

  • Farid zidat_20516
    Farid zidat_20516
    Altair Employee
    edited April 2022 Answer ✓

    Yes, the sum of Z1 and Z2 matches with the impedance seen by the source in the case without the capacitor.

    image

    Thanks Yerai!

     

    So as you can see, adding Z3 without represente it in the circuit is not true, because the capacitance will add reactive energy that will have an impact on the two solid conductors. That's why you had these wrong results.

    The current through the solid conductors in series is not the same with or without the capacitance.

    Regards 

  • Yerai Moreno Lafuente
    Yerai Moreno Lafuente Altair Community Member
    edited April 2022

    Thanks Yerai!

     

    So as you can see, adding Z3 without represente it in the circuit is not true, because the capacitance will add reactive energy that will have an impact on the two solid conductors. That's why you had these wrong results.

    The current through the solid conductors in series is not the same with or without the capacitance.

    Regards 

    Thank you very much.

    Regards