Hello,
Can you please suggest me an alternative part to 56P3362 which was used as gate transformer?
One followup question: What is the function of this circuit? I noticed there is no additional circuit to avoid deep saturation of the optocoupler. Is it not necessary?
56P3362 is a custom part - it is not likely to have a pin-to-pin compatible with same specs - we do not know at least. Its specs are as below and you can find alternative o similar based on the below specs if your design is with the same resonant parameters. If you have different resonant parameters, you may need to find out if the specs are still ok to your design.
The blue blocked circuit in your message is for output over voltage protection.
