Modeling and control of DC-DC buck converter using SMC

In this paper, a small-signal circuit modeling for pulse width modulated dc-dc converter operated in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are presented. Various aspects of modeling is discussed and then averaged modeling of PWM converter is selected. A duty ratio constraint (which comes in DCM), defines the diode conduction interval which is key to accurate prediction of high frequency behavior. Linear as well as nonlinear control strategies are implemented and their results are compared. Nonlinear control is preferred approach because no constrain on the signal variation around the steady state point. The proposed model and control strategies are implemented on buck converter. Simulation results have been shown for both the control strategies.