Tuesday, 27 March 2018

Circuit Solving using Newton Raphson Method

We used Matlab as the coding platform for solving the given circuit. 
We start by declaring a temporary variable which will be later used to store the value of the voltage at a particular node.We run the code in a while loop until we get a constant value and then it breaks out of the loop. This code also prints the number of iterations that were required to get to the final value. 


We solved the following circuit :
                                                       


Now for the given circuit we write A KCL equation at node Vout which will be:


                                    

Following is the formula used:
Image result for newton raphson

When we run this code we get Vout = 0.18V and the number of iterations is 44.
Now we simulate the given circuit in 'Every Circuit' which is an android application. Here after simulation we get Vout as 0.18V. 


Thus we can see that the value of voltage in both the tests match. 

The most difficult part in this experiment was writing the equations. The reason behind this was the use of diode. Diode is a nonlinear component thus its behavior is different from linear components i.e. current through the diode is exponentially proportional to the voltage across it as seen in the KCL equation above.

Now lets discuss some other numerical methods. Here in Newton Raphson method  convergence of output depends on the starting value. The rate of convergence here is quadratic. Now lets look at Bisection method, here there is guaranteed convergence and here the rate of convergence is proportional to the number of iterations. In Secant method convergence is unreliable so this method is not used in most cases. There is a numerical method which is easy to code which is known as iterative method. The convergence is unreliable here too. In Regula Falsi method convergence is guaranteed. Thus if we want a reliable convergence with less number of iterations then we use Bisection method


By- Gopala Dhar
Bharadwaj Bhat
Tejveer Singh

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