Question about simulation in Simulink

I'm a university student and now I am trying to make a model of fuel cell system but there is a problem.

when I start a simulation, there is a problem. When i use a variable step solver, the simulation speed is too slow. Besides, when i use fixed-step solver, the error is occured like this: Derivative input 1 of 'system_block_diagram_practice_stack_exceptv/Cathode/m,w,ca' at time 0.1 is Inf or NaN. Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)

I can't understand why this situation is happening. is there anyone who has similar situation or who can solve this problem please?

c.f) my Simulink model has some ODEs,for expressing mass and energy conversation, so i think it could be a problem, but i can't understand why the simulation speed is too slow.

[Azzi Abdelmalek]

what do you mean by too slow?

Answer 1

[Ryan G]

Check out this answer regarding the inf/NaN issue.

Regarding simulation speed, it's hard to say what slow means if you are coming across a singularity. Sounds like a modeling issue which may be resolved by starting at the link above.