Here is the OrCAD results;
Actually i do not know how to calculate feedback network accurately. I am really confused that which book is good for calculating. Since I've used marty brown's power supply cookbook, presmann's switching power supply design and basso's book. Pressmann's book does not tell anything about TL431 feedback with optocoupler. Marty Brown's book is pretty good but i am really confused to calculate some equations about feedback network. Basso's book is great but it needs some parameters such as needed gain and phase margin. So I've used Marty Brown's book for calculating but according this book, one resistor in compensation network in TL431 appears as 1054Mohm which is not realistic. Could you tell me which book you have been using for calculating feedback network and compensation ? I really need that. And I've also tried to simulate whole circuit via OrCAD but OrCAD always gives an error during the simulation. Here is the schematic and error.
INFO(ORPROBE-3183): Simulation running...
** Profile: "SCHEMATIC1-Full-Bridge" [ D:\Electrical & Electronics\Power Electronics\Simulation & Schematics\Orcad\full-bridge-pspi
Reading and checking circuit
ERROR(ORPSIM-16276): Can't find library
Circuit has errors ... run aborted
See output file for details
INFO(ORPROBE-3188): Simulation aborted
I am using UC3825 model which is in OrCAD's own library but it also gives an error as follows:
WARNING(ORNET-1018): Connection to unmodeled pin U8 pin 'RT'
WARNING(ORNET-1018): Connection to unmodeled pin U8 pin 'CT'