Clock pulse modulation for ripple reduction in buck-converter circuits

DC-DC switching converters which are frequently treated as hybrid dynamical systems exhibit complex behavior due to nonlinear and interrupt characteristics. For synchronous buck-converters, we propose a method to control chaotic behavior by pulse-frequency modulation. An input voltage, a duty ratio of PWMs, and so on, affect to the regulation characteristics of converters directly, but a frequency of PWMs is determined by the frequency characteristics of the converter and is set as a fixed value. The proposed chaos-control method suppresses chaotic responses by slightly perturbing the pulse frequency alone, therefore our method can stabilize unstable periodic orbits without influence on the voltage regulation scheme. To simplify the feedback controller, the condition of dimension reduction for the controlling gain vector is derived. The proposed controller achieves the stabilization without a current sensor. Numerical simulation and circuit implementation demonstrate the validity of this method.