Duty cycle control scheme to guarantee practical stability: A case study in DC-DC buck converter

Stability property is the key index for converter control. A practical stable control scheme is proposed for DC power supply converters. Firstly, the converter system is described as a linear model with two constraints, one is that the input is discontinuous and it is a Finite Control Set (FCS), the other is that the switching frequency is limited. Secondly, a unified control design method satisfied the constraints to guarantee the practical stability and convergence called sampling point equivalence scheme is introduced, which is illustrated as the duty cycle feedback control in form. Then the relationship between the convergent zone and the sampling time is analyzed, which is also the character of practical stability. The DC-DC buck converter is chosen as the plant to show the proposed methods, which are finally validated by both simulation and experiments.