Flyback Converter Simulation in PSpice

Hello guys,

I am simulating a flyback converter in PSPICE,

I am getting excellent results when i simulate with "VPULSE" signal to MOSFET, But when i put the actual model of the PWM controller with max duty cycle 50% , i observe that the the converter starts with 50% duty cycle for few cycles, now the out put increase above the desired value and the the controller shutdown without any pwm signal, after few usec the output volatge reduces below the required and pwm controller generates burst of pulses , and voltage rises and controller turns off. and the cycle repeat.


The interesting thing is tat the actual circuit works perfectly with different load condition, which working fine in real hardware.

any suggestion to check???

regards
Prasanna sinthaje

If you're expecting meaningful answers, you should consider to tell more about the used PWM controller and your simulation circuit...

hi
would you please upload your circuit here?

thanks

is your controller shutting off on overload protection function?
Or your feedback compensation may be bad
maybe your output capacitor is too small?