Transformer Simulation Issues – Clarification Required

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I am simulating a transformer with primary and secondary coils wound around the core limb. During the simulation, I encountered the following issues:

1. Issue with B-H Curve and Flux Density • I have assigned the B-H curve as the material property for the core. • After running a stationary study, the maximum flux density (Bmax) is showing approximately 400 T. • This value is physically unrealistic, since ferrite materials typically saturate around 0.3–0.5 T.

Question: Why is the simulation showing 400 T? Where could I be making a mistake in the setup?

2. Open Circuit and Short Circuit Giving Same Results

• When I excite one coil (either with voltage or current), • And apply open-circuit or short-circuit conditions to the other coil, • The simulation results remain the same in both cases. This behavior is unexpected because: • In open-circuit condition, only magnetizing current should flow. • In short-circuit condition, high current limited by leakage inductance should flow.

*Question: Why are both cases producing identical results? What mistake in the modeling or boundary conditions could be causing this issue? *



3 Replies Last Post 25 févr. 2026, 08:05 UTC−5
Edgar J. Kaiser Certified Consultant

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Posted: 1 day ago 24 févr. 2026, 04:36 UTC−5

First of all you must add another Ampere's law with the BH constitutive relation for the core domain. There may be more issues.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
First of all you must add another Ampere's law with the BH constitutive relation for the core domain. There may be more issues.

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Posted: 3 hours ago 25 févr. 2026, 07:07 UTC−5

Thanks @Edgar J. Kaiser for your valueable suggestion. Now can you address the second doubt.

  1. Open Circuit and Short Circuit Giving Same Results
  • When I excite one coil (either with voltage or current), and apply open-circuit or short-circuit conditions to the other coil, The simulation results remain the same in both cases. This behavior is unexpected because:
  1. In open-circuit condition, only magnetizing current should flow.
  2. In short-circuit condition, high current limited by leakage inductance should flow.

*Question: Why are both cases producing identical results? *

**Below is the attached modified COMSOL file with the two pictures as with V=0 and I=0 in coil 2 **

Thanks @Edgar J. Kaiser for your valueable suggestion. Now can you address the second doubt. 2. Open Circuit and Short Circuit Giving Same Results * When I excite one coil (either with voltage or current), and apply open-circuit or short-circuit conditions to the other coil, The simulation results remain the same in both cases. This behavior is unexpected because: 1. In open-circuit condition, only magnetizing current should flow. 2. In short-circuit condition, high current limited by leakage inductance should flow. *Question: Why are both cases producing identical results? * **Below is the attached modified COMSOL file with the two pictures as with V=0 and I=0 in coil 2 **


Edgar J. Kaiser Certified Consultant

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Posted: 2 hours ago 25 févr. 2026, 08:05 UTC−5

A transformer isn't working in stationary conditions. So it doesn't matter if the secondary coil is open or shorted, because nothing is happening there. You must apply a time dependent current e.g. a sine function to the primary coil and use a respective time dependent study to see any induction into the secondary coil. I think there are transformer examples in the application library and also contributions in the COMSOL blog. I recommend to check those. You should also make yourself familiar with the theory of transformers and inductive devices.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
A transformer isn't working in stationary conditions. So it doesn't matter if the secondary coil is open or shorted, because nothing is happening there. You must apply a time dependent current e.g. a sine function to the primary coil and use a respective time dependent study to see any induction into the secondary coil. I think there are transformer examples in the application library and also contributions in the COMSOL blog. I recommend to check those. You should also make yourself familiar with the theory of transformers and inductive devices. Cheers Edgar

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