Solving DC Motor Problem on Physics Forum

[ATRIX]

People of physics forum
i have come here to ask for help.
i am trying to model a armature controlled dc motor with no load but and opposite force in the form of frictional damping

the expression i have raised and am assuming it to be right is

ωout/Vin = k/(L(s)+R)(I(s)+C)+ kt.k


where K,kt are constants
L inductance
I inertia

R resistance armature circuit
C damping

the reference voltage is 25 volts. i really need i think a partial fraction expansion of this to allow me to do the inverse laplace transform

any body out there can you help me please?

thanks people.

 

[rude man]

What does "kt.k" mean? Is it kt multiplied by k which you can write as (kt)(k)?

Ω(s)/V(s) = k/[(sL+R)(sI+C)+ (kt)(k)] ?

The denominator is a second-order response. I would put in numbers to determine if this is an over- or under-damped system , then use Laplace tables. If you use partial fraction expansion that is OK but you'd better know how to handle the complex fractions.

 

[ATRIX]

Hey rude man, thanks for getting back

Yes you are correct k and Kt and yes they can be expressed in the form you have shown. They relate to the properties and generated emf. I think but am not sure that they are possible the time constant for the circuit the "Tau" value any ideas?

 

[rude man]

Hey rude man, thanks for getting back

Yes you are correct k and Kt and yes they can be expressed in the form you have shown. They relate to the properties and generated emf. I think but am not sure that they are possible the time constant for the circuit the "Tau" value any ideas?

k*Kt would have to have dimension = T (time). But if your denominator is consistent, k*Kt has the dimensions RIT^-1 = RMLT^-1.

Anyway, if you believe your transfer function is correct, why are you speculating about a time constant? Do you have numbers for K and Kt including their units?

 

[rezeew]

Hello!

From your post, it seems like you are trying to model a DC motor with no load and frictional damping. The expression you have raised looks like a transfer function, which is commonly used to model systems in control theory. It is great that you are seeking help on a physics forum, as there are many knowledgeable individuals who can provide valuable insights and assistance.

To solve your problem, you can first start by simplifying your expression. This can be done by factoring out the constants and using the properties of Laplace transforms. Once you have a simplified expression, you can then perform a partial fraction expansion to obtain the inverse Laplace transform. This will give you the time-domain representation of your system, which can be used to analyze its behavior.

It is also important to make sure that your model accurately represents the physical system you are trying to simulate. This can be done by comparing the results of your model with experimental data or by consulting with experts in the field. Additionally, you can explore different control strategies to improve the performance of your motor.

I hope this helps you in solving your DC motor problem. Good luck!