  In this paper, an optimal approach based on on-off controller is used to
optimally control a DC-DC step-down converter. It is shown that the
conventional controller techniques of DC-DC converters based on a linearized
averaging model have several drawbacks, including different operating mode,
linearization concerns, and constraint difficulties. A single-mode discretize
state-space model is used, and a new optimal approach policy is implemented to
control a step-down DC-DC converter. The simulation results confirm that the
proposed DC-DC model associated with the optimal controller functions properly
in controlling a DC-DC unfixed switch-mode step-down converter that is facing
load changes, noisy inputs, and start-up procedure.
