Variable-size signals within an algebraic loop

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Uli Sommer 2019-6-25

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/468860-variable-size-signals-within-an-algebraic-loop

编辑： Uli Sommer 2019-6-27

Dear Team & Users,

I am quite new to Matlab and Simulink and have been struggling for a couple of days with my newest model.

It is supposed to represent a multicomponent chemical reactor (FTS Reactor) and a product separation unit (Flash). My goal is to represent the behaviour of the system with a product recyle loop (algebraic loop) until it reaches a steady state. (see Diagram)

I work with a multicomponent reaction which produces variable-size signals. (M_dot_'')

I haven´t been able to get the loop to work. I already tried to implement the following:

Unit Delay
Memory Block
Transfer Fcn.

and failed.

I then tried it with a unit delay in an enabled subsystem which resets its states when enabled (next image) and got the following Error:

Block '.../MATLAB Function' has variable-size signals, and it resides within an algebraic loop. Variable-size signals do not support algebraic loops. Consider eliminating the algebraic loop.

How can I eliminate the algebraic loop and still solve my problem?

Let me know if you need any additional information

Best regards

Uli

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Uli Sommer 2019-6-26

编辑：Uli Sommer 2019-6-27

In the following thread a similiar problem is described:

https://fr.mathworks.com/matlabcentral/answers/99154-how-can-i-create-a-unit-delay-block-that-accepts-variable-size-signals-and-does-not-need-to-be-place

I tried to implement the 2-Level Matlab by saving it to an m.file and calling it in an S-Function

I got the following error:

Error evaluating registered method 'PostPropagationSetup' of MATLAB S-Function 'msfcn_varsize_delay' in 'recycle_FTS/Level-2 MATLAB S-Function'. The following is the MATLAB call stack (file names and line numbers) that produced this error: 
 ['C:\Users\ulric\Desktop\MA\Simulink\FTS\msfcn_varsize_delay.m'] [67]
Caused by:
Invalid dimensions specified for Dwork 1 of 'recycle_FTS/Level-2 MATLAB S-Function'. Dwork must be a vector, and its width must be a positive integer 