# Thermal description and simulation errors

**URL:** <https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238>\
**Category:** PLECS\
**Tags:** thermal-model-igbt-simulation\
**Created:** [May 12, 2023, 11:31am UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238 "2023-05-12T11:31:54Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![JungWoo](https://avatars.discourse-cdn.com/v4/letter/j/da6949/32.png) [@JungWoo](https://forum.plexim.com/u/JungWoo)\
**Post date:** [May 12, 2023, 11:31am UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238/1 "2023-05-12T11:31:54Z")

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hi 🙂

I tried simulating the IKZ75N65EH5 device, one of Infineon’s igbt types.

However, an error similar to the attached file occurred and I would like to inquire about a solution.

At first, I thought the error was caused by the lack of a heatsink, so I added a heatsink. However, an additional error occurred.

And I added IKZ75N65EH5 to the column description, turn-on loss and turn-off loss are not entered correctly. Could this be related to the error?

I would appreciate it if you could tell me how to run the simulation in the situation like the picture.

 ![11.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/a8eb73409890509a9becc46e2fd886fc5ac63037.png)

 ![22.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/31dc8ecbcff578b7d11e595f103fc8ffb8fd808c.png)

 ![44.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/5a534be42ab04866de84a0139005b005d5e1c728.png)

 ![55.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/19737a9c72c036883ee07c8213fe4781aecbccd6.png)

 ![66.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/1fbe24a09db11c66fe3ea0d0cecd1738cc6d2254.png)

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<div class="post-metadata">

**Author:** ![Kris\_Eberle](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/kris_eberle/32/6_2.png) [@Kris\_Eberle](https://forum.plexim.com/u/Kris_Eberle)\
**Post date:** [May 12, 2023, 12:28pm UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238/2 "2023-05-12T12:28:48Z")

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The heatsink needs to be connected to a Temperature reference point. Please attach to the heatsink thermal connection a Fixed or Controlled Temperature Source and (thermal) ground it.

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<div class="post-metadata">

**Author:** ![JungWoo](https://avatars.discourse-cdn.com/v4/letter/j/da6949/32.png) [@JungWoo](https://forum.plexim.com/u/JungWoo)\
**Post date:** [May 13, 2023, 1:58am UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238/3 "2023-05-13T01:58:41Z")

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thank you

The simulation worked.

There is something additional I would like to ask you.

As shown in the attached figure, the representation of switching loss is not reflected. how can i solve it?

The following equation is entered for the switching loss.

max(lookup(‘e\_rg\_on’, Rgon)\*lookup(‘e\_tj\_on’, T)\*lookup(‘e\_i\_on’, i)\*lookup(‘e\_v\_on’, v)/(lookup(‘e\_i\_on’, 37.5)^3) \*1e-3,0)

max(lookup(‘e\_rg\_off’, Rgoff)\*lookup(‘e\_tj\_off’, T)\*lookup(‘e\_i\_off’, i)\*lookup(‘e\_v\_off’, v)/(lookup(‘e\_i\_off’, 37.5)^3) \*1e-3,0)

Is something wrong with your formula? If not, what could be the problem?

 ![11.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/3677c722af3da71189cc01352f37094d7956f36e.png)

 ![22.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/a10bdfc792a000fa8f180ba92c2f13e5a0e33597.png)

 ![33.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/deb1df393a7557eeda830c8a5de49aa1bc526cdc.png)

 ![44.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/8c1f3543cc63b9a75a7d9a9c5b663f33a8b7b568.png)

 ![55.png](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/1X/bf73f4989d7e7fa0dc10d6338991ca0f02154dea.png)

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<div class="post-metadata">

**Author:** ![Kris\_Eberle](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/kris_eberle/32/6_2.png) [@Kris\_Eberle](https://forum.plexim.com/u/Kris_Eberle)\
**Post date:** [May 15, 2023, 2:01pm UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238/4 "2023-05-15T14:01:32Z")

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Hi again. Glad to hear that worked.

Yes, the standard Turn-on and Turn-off losses tables are not used directly, but rather, the manufacturer included “Custom Tables”, which are accessed from another tab to the right of the Thermal Editor GUI. There you will find the ‘e\_rg\_on’, ‘e\_tj\_on’, etc. tables that are then invoked by the formulas.

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<div class="post-metadata">

**Author:** ![JungWoo](https://avatars.discourse-cdn.com/v4/letter/j/da6949/32.png) [@JungWoo](https://forum.plexim.com/u/JungWoo)\
**Post date:** [May 15, 2023, 9:09pm UTC](https://forum.plexim.com/t/thermal-description-and-simulation-errors/1238/5 "2023-05-15T21:09:55Z")

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Thanks, solved all problems.

Have a good day ! 🙂