Help me understand this warning message

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Nuno
Nuno 2011-7-7
Is this an important warning?
Warning: Block diagram 'mesmotestesSoBatTerra' contains 1 algebraic loop(s). To see
more details about the loops use the command line Simulink debugger by typing "sldebug
mesmotestesSoBatTerra" in the MATLAB command window. To eliminate this message, set
the Algebraic loop option in the Diagnostics page of the Simulation Parameters Dialog
to "None"
Found algebraic loop containing:
'mesmotestesSoBatTerra/Subsystem/Simulink-PS Converter1/EVAL_KEY/SFUN'
'mesmotestesSoBatTerra/Subsystem1/Solver Configuration/EVAL_KEY/SFUN' (discontinuity)
'mesmotestesSoBatTerra/Subsystem/PS-Simulink Converter/EVAL_KEY/SFUN'
'mesmotestesSoBatTerra/powergui/EquivalentModel1/State-Space' (discontinuity)
'mesmotestesSoBatTerra/Subsystem/Voltage Measurement/do not delete this gain' (algebraic variable)
Warning: Discontinuities detected within algebraic loop(s), may have trouble solving
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Walter Roberson
Walter Roberson 2011-7-14
Please do not create new Questions to "bump" existing topics. Duplication of questions results mostly in duplication of efforts.

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回答（4 个）

Laura Proctor
Laura Proctor 2011-7-7
You have an algebraic loop in your diagram which will slow-down your computation time and may not converge to a solution. You can identify which loop it is by setting the Algebraic Loop option (Simulation --> Configuration Parameters --> Diagnostics) to ERROR.
Generally it is due to a feedback loop that contains a sequence of direct feedthrough blocks. This algebraic loop can often be modeled without using feedback, if you do the math.
Kaustubha Govind
Kaustubha Govind 2011-7-7
Nuno
Nuno 2011-7-8
My loop is this: http://img808.imageshack.us/img808/3449/loop.png
And said this: Block diagram 'mesmotestesSoBatTerra' contains an algebraic loop. The algebraic loop solver is disabled because of the current setting for Algebraic loop option in the Diagnostics page of the Configuration Parameters Dialog
Why i resolved this?
  2 个评论
Kaustubha Govind
Kaustubha Govind 2011-7-8
It's not clear what you question is. Please explain what you mean by "Why i resolved this?" - it doesn't seem like you have resolved the algebraic loops from the above message.
Arnaud Miege
Arnaud Miege 2011-7-8
Have a look at the answers and comments I gave to one of your previous questions:
http://www.mathworks.co.uk/matlabcentral/answers/9053-doubt-in-circuit-of-battery
I explain that interfacing Simscape to SimPowerSystems "will likely introduce an algebraic loop in your model, that you may need to break with, say, a low-pass filter (transfer function) with an appropriately chosen cut-off frequency."

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Nuno
Nuno 2011-7-12
How i put the low-pass filter?
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Arnaud Miege
Arnaud Miege 2011-7-15
Use your engineering knowledge. What is the highest frequency component you'd expect? Set your cut-off frequency to be higher than that. Set a gain of 1.
http://en.wikipedia.org/wiki/Low-pass_filter#Laplace_notation
Nuno
Nuno 2011-7-18
But i don´t understand where i put a tranfer function?

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