Optimum design approach of high frequency transformer

Design an efficient high frequency transformer or inductor is based on accurate core loss and winding loss models. Steinmetz and Dowell's equations are the most common methods used for this purpose. The selection of the optimum magnetic core depends on both: the core and the winding losses. The core geometry coefficient is a popular method which Steinmetz equation, valid for sinusoidal excitation, and the DC copper loss formula are coupled together to determine the suitable magnetic core. However, in switching power supplies, excitation waveforms are non-sinusoidal. This implies that the frequency and the duty cycle can have a great effect on the core and copper losses. As a result, the magnetic core could be undersized which leads to decrease the efficiency. The main contribution of this paper is to develop a simple and compact formula to select the optimum magnetic core. This formula includes the effects of the frequency and the duty cycle on the magnetic and winding losses.