Hello i want to know is there any equation that detemines the best frequency for a ferrite transformer(high frequency transformers)?

 

http://tahmidmc.blogspot.com/2012/12/ferrite-transformer-turns-calculation.html?m=1

 

No. The subject is too complicated for that. To begin with, to what purpose would the transformer be put?

Often operating frequency is chosen based on experience and judgement and then the core material is chosen for that frequency.

 

any equation that determines the best frequency

You start with the manufacturers claims about the core material then do some calculations about the parts that will drive the transformer. The availability of fast switching transistors was the limiting factor for a long time.