Qualitative Analysis and Control of a DC-to-DC Boost Converter Operating in Discontinuous Mode

The boost cell operating in discontinuous conduction mode-based on an approximate discrete-time difference equation is investigated. A qualitative discussion of the steady-state and open-loop dynamical behavior is first presented. A linearized small-signal equation is derived that leads to a linear feedforward control law for regulating this type of converter. This conventional linear scheme provides satisfactory control in the neighborhood of the operating point, but ceases to meet the requirement as soon as the small-signal assumption is violated. A nonlinear feedforward control law, whose validity extends over a wider range of fluctuation of the variables about the operating point, is proposed along with some simulation results that confirm the superiority of the proposed nonlinear control over its linear counterpart.