Doubt with the simulink units.

I have made a model with time in hours. The simulation in simulink (the scope) shows it in hours or in seconds? Thank you so much.

[Carlos]

Some help please?

Answer 1

[Ralf]

It shows the time in seconds.

[Carlos]

But... how is it done? I mean, if my differential equations are all in hours, how is it possible that simulink calculates in seconds? And, then, what is the best option, to change all the differential equations to seconds?

[Ralf]

Simulink assumes that one simulation step equals one second. If you model your system using time constants in hours, one Simulink time step equals one hour. If you set for example Simulation end time to 10, it would mean 10 hours.

That would work as long as you are using Simulink alone and as long as you model all time constants in Units of hours. But in case you use one of the physical modeling toolboxes like Simscape, Simulink assumes that one step equals one second. In case you want to simulate your model in conjunction with these physical modeling toolboxes, you'll need to rewrite your model to a timescale in seconds.