Abstract:

It is very complicated to determine the size and type of the magnetic cores for the flyback transformers used in switching power supplies.Based on Nomogram,a simple method is proposed to choose the optimal magnetic core and determine the optimal parameters such as the swing of magnetic flux density,according to the work frequency and rated power.The efficiency is enhanced when using this method.A flyback transformer for a 24 V switching power supply is designed utilizing this method.The ripple voltage amplitude is measured to be 0.22 V,less than the required 1% of the rated voltage,showing that this method is feasible and practical.

Key words: switchmode power supply;flyback transformer;nomogram