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unable to meet integration tolerances.

0 votes
I was trying thermal simulation of 3phase H bridge inverter powering a BLDC motor.I am encountering an error Unable to meet integration tolerances without reducing step size below smallest value allowed (2.6589e-17).How to solve this one. Does this issue had dependence on system memory requirements.?
asked May 14, 2021 by reshma (12 points)

1 Answer

+1 vote

There is not enough information to answer this question.  Please post your model and thermal descriptions to the forum or reach out to

Speaking generally in the context of simulations with thermal models, this issue may occur when you have an ill conditioned thermal system with temperatures approaching infinity.  If you inspect the temperatures and losses in your system, are they reasonable?

If your temperatures are unreasonable, below are some general debugging steps to follow:

  1. Remove all thermal models and ensure the electrical simulation is performing as expected including any controls.
  2. Confirm the devices you have chosen are appropriate for your design.
  3. Look for paths of high thermal impedance, which can lead to runaway temperatures. Consider the thermal impedance values chosen.
  4. Review the thermal description file.  Are the losses reasonable and of the correct units?  Another potential issue may arise due to interpolation in the loss description lookup tables, as discussed in this forum post. Reach out to for more specific guidance.
Note that Plexim support will be limited if the source of the thermal problem is due to the system design and not a fundamental PLECS issue.
answered May 14, 2021 by Bryan Lieblick (1,887 points)