[Simulink] "virtual" algebraic loop vectorizing a block

Hello

for a while I use this trick (vectorize a block) to implement n block

which is the same than this :

but simulink see an algebraic loop (which doesn't really exist) :

if fact my model is more complex (Saint Venant equations)

Until then there was an error, and an integrator bloc was breaking the "loop"

but now I correct this error and the loop come back beacause the integrator had disappear from the "looped signal" (example) :

I can't break the loop using usual solutions (delay, filter ...) because it would make false my differentials equations

the only solution I see is to write the developped form (fig 2) using "addBlock" fonction from mask

my question is :

- do you see a solution to "break the loop"

- do you know another way to "vectorize" a block

thanks (and sorry for my English)

Fabien

Answer 1

[User_in_Gim]

Hi Fabien,

You are using the previous value to find your current value so yes, there is an algebric loop.

The most efficient way to "break" the loop is to place your integrator loop on your feedback signal.

With this implementation, you will not have an algebric loop.

[fabien grand perret]

thans but i can't use this solution

this solution is OK when you loop for control command (PID ...) but here my model is a system of partial differential equations where I use this tricks to discretize on x and I keep "d/dt part" so a delay introduce an error on "d/dt part"

and i am not using the previous value to fing the current value !! see fig 2