Solving coupled ode in matlab help

[cjh12398]

Problem: Model the coupled ode system for a motor:
Equations:
dVc/dt=(-1/C)*Il+(1/C)Is
dIl/dt=(1/L)*Vc-(R/L)*Il

I have been given the values of L=1e-3, R=50, Is=10.0A and C is to be designed by trial and error.
I have been able to write out the function, by assigning Vc=x(1) and Il=x(2), and then I wrote dxdt= [dVc/dt;dIl/dt];

But when I have my script, I'm having trouble in how to define the initial conditions. The task says that all currents and voltages are zero at the beginning and I have therefore written that x1=0 and x2=0.

However, when I plot the result, the current value is way lower than what is expected.
I suspect there is a problem in the way I am defining the initial conditions.
Any help would be greatly appreciated.

 

[NateD]

Solution: In this case, you should use the given values of L, R, and Is to calculate the initial conditions for your system. The initial voltage Vc can be calculated from the equation dVc/dt=(-1/C)*Il+(1/C)Is, as Vc(0)=(Is*C). Similarly, the initial current Il can be calculated from the equation dIl/dt=(1/L)*Vc-(R/L)*Il, as Il(0)=(Vc(0)*L)/R. Thus, you should use these initial conditions, x1=Vc(0) and x2=Il(0), when defining your system.