On Thu, Feb 27, 2025 at 09:58 AM, Robert wrote:
Later this morning I added the remaining five SMPS's. I would like each to have its own reservoir cap, so I can measure the DC current each contributes, but that just results in a convergence failure. So I'm having to live with them sharing one big capacitor in the model.? ?Same (perfect) capacitance in the same electrical location, but one way of achieving that works and the other doesn't.
Let me see if I understand.? You have
3? 5 or 6 ideal capacitors connected in parallel, which fails?? And when replaced by one ideal capacitor with the same total capacitance, it doesn't?
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I just want to make sure you did not accidentally select capacitors from LTspice's "Select Capacitor" menu.? All the capacitors in that menu are complex models for real (purchasable) capacitors, including parasitics.? They aren't ideal.? I'm assuming you didn't do that.
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So let's say the capacitors you used really were ideal.? Of course it should not have made any difference whatsoever.? The fact that it does, suggests that you are right on the hairy edge of instability, and even the slightest change in matrix element calculations, caused one version to fail.? Could have gone either way.
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Andy
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