# Negative conduction loss in the diode and IGBT

**URL:** <https://forum.plexim.com/t/negative-conduction-loss-in-the-diode-and-igbt/2679>\
**Category:** PLECS\
**Tags:** thermal-model\
**Created:** [November 5, 2025, 3:07pm UTC](https://forum.plexim.com/t/negative-conduction-loss-in-the-diode-and-igbt/2679 "2025-11-05T15:07:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![NaihaniPereira](https://avatars.discourse-cdn.com/v4/letter/n/f07891/32.png) [@NaihaniPereira](https://forum.plexim.com/u/NaihaniPereira)\
**Post date:** [November 5, 2025, 3:07pm UTC](https://forum.plexim.com/t/negative-conduction-loss-in-the-diode-and-igbt/2679/1 "2025-11-05T15:07:47Z")

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I am performing electrothermal modeling of semiconductors, and I am getting negative losses for the diode and IGBT. I set the current and voltage points to 0A and V respectively for all losses, but the error persists.

 ![image](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/2X/8/810f7f9c8682d4a61de92164ad46b29a35244fbc.png)

 ![image](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/2X/5/5617a70c12d453dcbd2b4f26ed9aef552ebd502b.png)

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**Author:** ![Bryan\_Lieblick](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/bryan_lieblick/32/10_2.png) [@Bryan\_Lieblick](https://forum.plexim.com/u/Bryan_Lieblick)\
**Post date:** [November 5, 2025, 4:39pm UTC](https://forum.plexim.com/t/negative-conduction-loss-in-the-diode-and-igbt/2679/2 "2025-11-05T16:39:57Z")

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This is an example of an extrapolation error occurring at very high temperatures. The device temperature is over 100,000 C. Please review the forum post below for suggestions on resoling the issue.

> [@Derived is infinite or NaN in hot simulation](https://forum.plexim.com/t/derived-is-infinite-or-nan-in-hot-simulation/1632):
>
> When using PLECS 4.7.4 software to perform thermal simulation on the inverter, I found that the temperature of the device would continuously rise to infinity. However, I removed the relevant settings for thermal simulation and only performed electrical simulation, and the circuit was running normally. I would like to know how to handle this issue so that my thermal simulation can run normally.

The PLECS Documentation also provides guidance for this error message. See below. Currently you have implemented the third approach, but clearly the simulation results are not meaningful as the device would have been destroyed. Solution 2 is the most relevant (halt your simulation on high temperatures and debug the underlying issues in the electro-thermal model).

 ![image](https://europe1.discourse-cdn.com/flex006/uploads/plecs/original/2X/4/4c2837fdfb4d7ff196709f678d63565aba9dc406.png)