Timeline for Why do I need a ground when simulating a circuit? I thought voltage was relative between two nodes!
Current License: CC BY-SA 3.0
7 events
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| Dec 6, 2017 at 21:59 | comment | added | user16222 | Personally I hate simulation tools... too often you have to "add stuff" to keep the simulators happy & for a so call complex tool they are not that smart... Then you have bad engineers who have no idea what the cct is meant todo in the 1st place blindly trusting the results | |
| Dec 6, 2017 at 21:56 | comment | added | user16222 | Exactly. Take a classic isolated flyback circuit. The "floating" side is something almost all simulators struggle with as it has nothing to reference against (SABER is nasty "jacobian maxtrix errors", SIMextrics a bit more tame... Simscape is funny.). The classic way of helping the simulator is a high impedance resistance to the reference node. If the simulator arbitrarily picked a node, what if it chose the other side of the XFMR for the next simulation? by forcing the user to denote the reference point it provides a level of certainty to the results | |
| Dec 6, 2017 at 21:49 | comment | added | Pete Becker | @Hamsterrific -- perhaps you saw my use of "limitation" as harsh. The reason that this circuit doesn't work in the simulator is that the simulator adds requirements that aren't present in real-world circuits. The circuit as drawn works just fine, despite the fact that the simulator doesn't like it. | |
| Dec 6, 2017 at 21:39 | comment | added | user16222 | But it would still be choosing a node.... The point is it needs something to reference against . If it arbitrarily chose a node how and where and between simulations would you be putting "probes". Every voyage probe would need to be differential (which isn't a problem that is how MATLAB works ) | |
| Dec 6, 2017 at 21:36 | comment | added | Pedro A | @PeteBecker I disagree. A complex tool like a simulator could very possibly choose an arbitrary node to be a reference and then perform all computations against that reference, but hide it to the user, and only show voltage differences to the user. This would be bad to the user experience, but that's all. Therefore by design, to assist the user, simulators require the user to choose the ground. It's just a convention. | |
| Dec 6, 2017 at 14:07 | comment | added | Pete Becker | Exactly. There's nothing wrong with the circuit. The problem is the result of a limitation in the simulator. | |
| Dec 6, 2017 at 12:51 | history | answered | user16222 | CC BY-SA 3.0 |