H bridge system for inverter using n channel mosfets
I am no expert on this type of inverter, but this answer comes from reading other articles and various YouTube videos. You need a dead period when all 4 mosfets are turned off briefly. Otherwise 2 transistors are partly on during the transition and effectively shorting the power supply. Have you set an adequate value for this with a resistor from Ct (pin 5) and the Discharge?

It is not clear from what I can find if there are not 2 different versions of the SG3525.
Some diagrams seem to show that it has 4 outputs for driving the H-bridge directly, or maybe they are synching two separate ones together in order to get the 4 phase drive without overlaps. I'm not sure. See the diagram in this note

There is an article on the design here

and I presume you have the data sheets either here or here

I hope this helps somewhat.