Behavior of InitialDC in Transient Simulation inconsistent with explicit IC

[drahnoel]

I am looking at transient simulations with initialDC=yes. This setting enables calculation of initial conditions based on an implicit DC simulation. However, I find the treatment of explicit initial conditions inconsistent. Currently, explicit conditions are not considered during the initial DC simulation, but then overrule the implicitly derived ones. See attachment.

I propose two more consistent approaches:

Proposal A:

With initialDC=yes, explicit initial conditions are always ignored and overruled by the implicit ones derived from the DC solution.

Proposal B:

With initialDC=yes, explicit initial conditions are respected during the initial DC simulation. Capacitors with explicit conditions are replaced with voltage sources, coils replaced with current sources.

Attachments:

1. Unexpeced-behavior-in-transient-simulation-with-initial-DC.docx

[QucsStudio]

Even though your thoughts make sense, I don’t think that the current behavior is inconsistent. Proposal A is not bad, but I still find the current solution the best one.

[drahnoel]

Ok.

There are some components, where one needs to use initialDC=yes, because they have no initial conditions fields. Example: Diode. (With initial DC=0, they always start with 0V at t=0)

However, I want to have different initial conditions as initialDC=yes calculates. So, what I do is to force the voltages to the desired initial conditions using a voltage source. To make the voltage source not affect transient simulation, I add a 1H inductance in series. This way I emulate the InitCond element of ADS.

This is the workaround I am successfully using at the moment.

[Author]

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