How can I simulate Inertia in Simulink?

Hello,

I got the following images:

Here I try to simulate the inertia of my system and translate it to rpm. The result is as follows:

I don't get why my rpm doesn't follow my torque line.. The initial value for my integrator is zero (speed at t(0) = 0). Could someone help me with this

[Babatunde Tolu Ogungbe]

Following the above makes me believe i am in the right place.

Please i need help to Simulate Inertia of a biogas plant. the biogas plant consist of (Anaerobic digestion,Microturbine with PMSG). I would be glad if i could get help.

[Paul]

Is the conversion from omega to rps correct?

Should it be 1/(2*pi)?

Answer 1

[Sebastian Castro]

Your model and response seem fine to me. Dividing the input torque by the moment of inertia is correct.

The acceleration you're providing is always a positive value ranging from 1250 to 1700 N*m, so your speed should keep increasing with a slightly varying positive slope.

In reality, there would be other subtractive terms before the inertia division corresponding to stiffness, damping, friction, etc. Maybe this is what's missing from your model that you would expect to see?

- Sebastian

[Igor Batoukhtine]

Thanx for your answer, I'm trying to model a centrifugal pump with inertia, but I'm still looking for a mathematical approach or equation that includes these losses due toe stiffness etc. Can you help me out with this?

[Sebastian Castro]

Well, a pump usually will have some sort of friction that depends on the speed of the pump. Generally, the faster the speed, the higher the friction force.

The simplest friction model would be viscous friction, or a damper:

Torque = - C * velocity

Where C is a damping coefficient. Try adding that to your model?

- Sebastian

[Igor Batoukhtine]

Dear Sebastian,

So the behaviour of the pump would be something like this:

Ia = Tpump - Tdamping - Tfriction - T...?

How can I define the coëfficient C? My total system looks like this: