Graphical small-signal modeling based on the inductor waveform

A graphical small-signal modeling based on the inductor waveform is presented in this paper. Small-signal perturbation is superimposed on the large-signal inductor waveform under steady-state condition and then the output voltage variation from small-signal perturbation is calculated by equivalent circuit. As a result, the small-signal transfer function (control-to-output transfer) is derived This approach to model switching DC-DC converter power stages has the merits: 1) the modeling is very clear and is simple whether the converter operates in the continuous conduction mode (CCM) or the discontinuous conduction mode (DCM) and 2) the modeling is simple and easy to understand and derive. With a boost converter operating in CCM and DCM as an example, the proposed small-signal modeling is shown to be easier.