Is K the cause of high voltage and current in my simulation?

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In summary, the conversation discusses a problem with a simulation (Multisim) where the voltage and current increase very high in a short time. The issue is narrowed down to the value of K and its effect on the energy input/output. The user also shares a circuit where there is a positive current in the transformer and questions whether this is possible and the role of Spice in this scenario. After further discussion and testing, it is concluded that the energy is stored inside the inductances and the software provides start values for current. The conversation ends with a humorous remark about the old days before the Internet.
  • #1
rf74
5
0
Hi,

I have a problem with my simulation (Multisim). I don't find the error. Voltage and current increase very high in a short time. It's only 3 selfs with coefficient at 0.9 for L1/L2 and for L2/L3. K is at 0 for L1/L3. I give image for the circuit and the result of simulation. The problem come from K ?

K1 LL1 LL2 0.9
K2 LL2 LL3 0.9

thanks
 

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  • #2
Hi,

Someone can help me ? I don't find my error. If I'm looking at energy input/output, the sum is no 0. I simulated with R1 and R2 at 1 MOhm but the circuit give high voltage. If K1 and K2 are under 0.5 it's ok, but with K1=K2=0.9 and K3=0, voltages at R1/R2 increase very high. I tested with another software and it's the same result.

K1 LL1 LL2 0.9
K2 LL2 LL3 0.9
K3 LL1 LL3 0.0001 or 0
 

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  • #3
Hi,

I found the problem, it's because I let K3=0, I can't do that, the minimum must be at K1K2.

I find a circuit where I can have a single sign current from a sinusoidal source, and the sum of energy is not zero. But is it possible in a self to have a positive current ?

I give you the circuit, I tested with Multisim and LTSpice, it's the same result.
 

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  • #4
Hi,

I simplify the circuit, it can be like:

vV3 14 9 dc 0 ac 1 0
+ sin(0 {90*1.414213562} 60 0 0 60)
vV2 0 6 dc 0 ac 1 0
+ sin(0 {90*1.414213562} 60 0 0 60)
rR4 11 4 1
K2 LL2 LL3 0.9
rR2 10 9 1
lL3 13 0 1
lL2 5 0 1

There is a positive current in transformer, the energy from the source is +V*I -V*I in a period, like I is always positive, the energy from source is 0. Like that it's logical, but energy must be conserved so it is a problem from Spice, the current at start is not like that in reality ? I think it could like that at start with an external DC source no ? I tested with Multisim and LTSpice. The difference of energy is 1200 J in a second. This is only in the transitive time. After current is at 0, no energy at output and no energy at input. If K=1 the energy is conserved, it's only when I let K=0.9 or 0.5. Angle phase must be at 60° for example, don't let it at 0°. Someone can test for verify my study ? It is the energy inside 1/2LI² ? At start I=110A so the energy inside selfs is LI²=121kJ.

If I let:

vV3 14 9 dc 0 ac 1 0
+ sin(0 {90*1.414213562} 60 0 0 60)

*## Multisim Component V2 ##*
vV2 0 6 dc 0 ac 1 0
+ sin(0 {90*1.414213562} 60 0 0 240)

The energy at outputisnot the same.

Thanks for your help
 

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  • #5
Hi,

I understood, it's because the energy is inside inductances ! Software give start values for current and there is energy inside inductances. All is fine !

bye
 
  • #6
Well done rf74. You constructed a whole, satisfactory thread with question, discussion and answer, all by your self!

In the old days, before the Internet, this was how we all used to solve problems. lol
 
  • #7
sophiecentaur said:
Well done rf74. You constructed a whole, satisfactory thread with question, discussion and answer, all by your self!

In the old days, before the Internet, this was how we all used to solve problems. lol

But it's 11 days of hard work . lol
 

1. Is K the only factor contributing to high voltage and current in my simulation?

No, there are likely other factors at play that can also contribute to high voltage and current in your simulation. These may include other components in the circuit, external interference, or incorrect simulation settings.

2. How can I determine if K is the main cause of high voltage and current in my simulation?

You can try running the simulation with different values for K to see how it affects the voltage and current. You can also use circuit analysis techniques, such as Kirchhoff's laws, to determine the impact of K on the overall circuit.

3. What is the significance of K in a circuit simulation?

K represents the conductance of a component in the circuit, which can have a significant impact on the overall voltage and current. It is important to accurately model the conductance of each component in order to get an accurate simulation.

4. Can K be the sole cause of high voltage and current in my simulation?

No, it is highly unlikely that K alone would cause high voltage and current in a simulation. It is important to consider all factors and components in the circuit when troubleshooting the cause of high voltage and current.

5. How can I reduce the impact of K on the voltage and current in my simulation?

You can try reducing the value of K or using a different type of component with a lower conductance. You can also try adding other components in the circuit to balance out the effects of K on the overall circuit.

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