Slide mode control via current mode control in DC-DC converters

We first study the behavior of a current-mode-controlled boost converter and exhibit its chaotic behavior (when the duty cycle exceeds 50%). We then introduce a practical method (sliding mode control) aiming at totally eliminating chaos and at keeping the desired current-controlled property. Indeed, the standard method (slope compensation) only partly cures this major drawback, even though it eliminates chaos, the converter is not current-controlled any more. Our control method does not only provide stability, it also increases the input voltage variation domain for which the system remains stable. The sliding-mode controlled converter always remains current-controlled, i.e. independently of the duty cycle. We finally establish a mathematical modeling of the whole circuit (close-loop) and study its performance in detail.