Custom Search

Wednesday, July 2, 2008

Step response of RLC Circuit by parametric analysis using PSPICE

The aim is to find the response of an RLC series circuit using parametric analysis by using Step input signal. Here using PSPICE we calculate and plot the capacitor voltage from 0 to 400micro seconds with a time increment of 1 micro second for resistance values of 1 ohm, 2 ohm, 8 ohm.

Hardware requirement:
An IBM 80486 or Pentium based PC with the following features:
  • 640kb of memory
  • Atleast 8mb of extended memory
Software Requirement:
Microsim eval. 8
PSCIPE Software package

PSCIPE Porgram for resistance value of 2 ohms

* Step response
* Source description
vs 1 0 pwl(0ns 0v 1ns 1v 1ms 1v)
* Component Description
r 1 2 2
l 2 3 50u
c 3 0 10u
*Analysis description
.tran 0 1us 400us
*Output description
The above program code can be repeated for resistance values of 1 ohms and 8 ohms just by replacing the value of resistance accordingly.


In the above program PWL stands for Piece Wise Linear
Throughout the code u stands for micro and us stands for microseconds. The units for resistance , inductance and capacitance need not be specified

If you consider line 5 in the program above i.e. " r 1 2 2 " . Here the 2 at the end is taken as 2 ohms by default and similarly in line 6 " 50u " indicates an inductor with 50micro henry.

The response can be analyzed graphically for resistance value of 1 ohm , 2 ohm and 8 ohm as follows :

Response for resistance with 8 ohms
Response for resistance with 2 ohms

Response for resistance with 1 ohmsInferences:
Following are the various parameters calculated for resistance values of 1 ohm, 2 ohm , 8 ohm respectively

1ohm 2ohm 8ohm

Rise Time : 44us 60us 158us
Delay Time: 14us 12us 12us
Peak Time: 75us 80us 400us
Settling time: -- 253us 12us

Conclusion: As resistance increases the rise time increases.

Note: Don't write the program from 1st line as its reserved for title of the program.

No comments: