After reading the book "Switching Power Supplies A to Z" by Sanjaya Maniktala, I derived the following expression for the switching loss (Pm) in the Miller region. All the parameters can be found on a typical mosfet data sheet.
//Back-of-envelope calculation of Miller-plateau crossover loss. //The Miller loss omits the loss as the drain current swings at VDS=Vin constant. //The Miller loss is the largest switching loss which occurs as VDS swings at IL constant theta=Qgs/(Qg-Qgd);//Ubiquitous gate-charge factor appearing in Miller loss formula Pm=(IL*Vin*Qgd*Rdrive*f/(2*Vdrive))*(1/(1-theta)+1/(theta-Vsat/ Vdrive)); where, //Parameters (SI units) f=500.0e3;//Switching frequency Vdrive=4.5;//Gate driver voltage high voltage Vsat=0.0;//Gate driver logic low voltage Rdrive=2.0;//Lumped drive impedance plus mosfet gate resistance Rg Vin=15.0;//Input voltage for the buck VDS(t=0) for all topologies IL=22.0;//Free-wheeling diode current //Mosfet parameters at a typical VDS Qg=36.0e-9;//Gate charge factor Si4442DY, VDS=15V, VGS=4.5V, ID=22A Qgs=8.0e-9;//Gate charge factor Si4442DY, VDS=15V, VGS=4.5V, ID=22A Qgd=10.5e-9;//Gate charge factor Si4442DY, VDS=15V, VGS=4.5V, ID=22A
Stephen