Fly-Buck Converter Parametric Analysis and ZVS Operation for Multiple Outputs

The Fly-buck converter provides a simple, lowcost solution to generating multiple isolated or non-isolated output voltage rails using secondary windings of the coupled inductor. Under certain operating conditions, the high side (HS) and low side (LS) switches can realize zero-voltage-switching (ZVS) at turn-ON, reducing switching losses and electromagnetic interference (EMI). However, several factors play a critical role in determining the soft-switching criteria. Therefore, this paper presents an in-depth analysis and evaluation of the ZVS operation through developing equivalent circuit models of the fly-buck converter along with a parametric study of the design variables, including leakage inductance, output current ratio, and dead time.