Application of the principle of energy conservation to modeling thePWM converters

摘要

Parasitic resistances and offset voltage sources of power switchesnare included in the averaged-circuit models of an actual switching partnof PWM transformerless converters which operate in a continuousnconduction mode. The actual switching part is divided into the idealnswitching part and its parasitics. It is shown that the ideal switchingnpart can be modeled by one of 24 equivalent averaged circuits, eachnconsisting of a dependent current source and a dependent voltage source.nThe parasitics are averaged using the principle of energy conservation.nThe obtained nonlinear large-signal model of the actual switching partncan be placed into the buck, boost, and buck-boost topologies leading tonaveraged-circuit models of power stages. Linearization of the modelnaround a DC operating point results in DC and small-signal models of thenconverters. Reflection rules are established which can be used tonsimplify the circuit models. The proposed method is illustrated bynmodeling the PWM boost converter