A unified modeling approach for DC-DC converters based on the three-state switching cell

Abstract

This paper proposes a general small-signal model for the representation of dc-dc converters based on the three-state switching cell (3SSC) operating in continuous conduction mode (CCM). Even though such power electronic converters present distinct behaviors depending on the duty cycle range i.e. 0 < D < 0.5 and 0.5 < D < 1, the developed analysis effectively shows that the derived model is valid in either case. An approach similar to the PWM (pulse width modulation) switch is employed, being this a fair, simple, and straightforward technique if compared with other similar ones e.g. average state-space modeling. Dc and ac small-signal models can then be obtained in order to provide relevant expressions associated to the converters e.g. the static gain and several transfer functions used in the implementation of closed-loop control. A dc-dc buck converter is also investigated, whose model is properly represented by mathematical expressions that are validated by simulation tests for both operating conditions of the 3SSC.