State Space Representation Does Not Work with Superposition Theorem

M

Thread Starter

mistermystere

Hi,

I need to get the state space model of an electrical circuit with 3 inputs (the voltage sources) and 1 output (voltage of a capacitor).

Using the superposition theorem, I managed to get each of the 3 differential equations (one for each source), and transforming them to state space (in Simulink) gives independently convincing results (time constant, and steady state value).

However, if I sum all these equations up to get the total one and transform it into a state space block in Simulink, the result is completely wrong (e.g. for 77-300-370 in and 338 out expected, I get 140...).

I thought we could do that with linear systems (which it is, only V-R-C components)?

I do apologise for linking to another forum (where it's unlikely I'll get an answer), but that one enabled me to format the question better (images+formulas).
http://math.stackexchange.com/quest...resentation-wont-be-linear-superposition-theo

Thank you in advance,
Kind regards
 
MisterMystere... further to my earlier post:

3) Does the circuit configuration consist of three (3) KVL loops, where two (2) represent sources, and the 3rd has one (1) source and a cap?

Regards,
Phil
 
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