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"Unable to meet integration tolerances" problem.

0 votes
Hi everyone!

Tonight I left running the simulation and this morning I found this error:

"Unable to meet integration tolerances without reducing step size below smallest value allowed (7.1072e-14)".

I have a 3-ph inverter system.
20 seconds from the start of the simulation there is a double open-phase fault simulated by a very very small load conductance (g=1e-8..maybe too small?) with a step block.

The strange thing is that it doesn't happen when I manually try the fault at 1 second from the start of the simulation.

Is it a problem about Plecs memory usage?
Maybe should I try to increase the conductance value because it is too small?

Also another question:
I have read that when there is the "Cyclic behavior" one of the possible solutions is to increase the diode turn-on threshold. Is this threshold a "voltage threshold" like Vt=0.7 or a "time delay"?

Thank you in advance!

asked Jul 27, 2018 by nikilito (112 points)

1 Answer

+1 vote
Best answer


Unfortunately we do not have enough information on the error you are encountering to make a suggestion here. For very specific modeling issues we request that you attach an example .mdl or .plecs file, or contact our support team at

Also, this text is from our user manual regarding the diode turn-on threshold setting:

Note  The Diode Turn-On Threshold is not equivalent to the voltage drop across a device when it is conducting. The turn-on threshold only delays the instant when a device turns on. The voltage drop across a device is solely determined by the forward voltage and/or on-resistance specified in the device parameters.

I hope this helps.



answered Jul 31, 2018 by Kris Eberle (1,245 points)
selected Aug 13, 2018 by nikilito