Feedback in pure sine wave inverter

[pakkiboy]

Dear members , I have designed Pure sine wave inverter
Input = 12 v DC
Output = 320 v DC , 220 v AC
Transformer = 400 W Ferrite core transformer .
In 1st stage I have used push pull topology to convert 12 v to 320 and in second i have used Microcontroller pic16f684 , IR2110 , And mosfet to convert 320 DC to AC.
mine main issue that circuit work well at no load condition but voltage drop at load (to about 265-270 V DC ) . I have used feedback of SG3525 but after all still voltage drop. Any idea how to maintain voltage constant . PLZ PLZ help
Regards
Qamar
Circuits attached

 

[mtwieg]

When the output voltage drops, what duty cycle do you see on the PWM outputs? It should approach 50% (on each channel) if the feedback is working.

 

[tariqzaheerpk]

say problem solved or not

 

[pakkiboy]

Unfortunately Not , I have tried alot , but still voltage drop . Any one can help plz ?

 

[zkalk]

Are Fast Recovery Diodes ;-)

 

[naseerak]

Try to increase the size of coils Primary/Secondary

 

[kabeer02]

Most of the sine wave inverters i know uses feedback for both dc-dc and the spwm section.