Controller for a reduced output current ripple DC-DC buck converter

This paper presents the modeling and control of a DC-DC buck converter with reduced output ripple which is achieved without additional switching devices. The converter results from replacing the LC output network in a conventional buck converter for an LCL network which is proposed to be implemented by using coupled inductors. Low output ripple is required when dealing with sensitive loads as in LED lighting applications and high precision test equipment. The functionality of the buck converter is preserved and the output current and voltage ripples are highly reduced. Active damping must be provided in order to mitigate resonant behaviors. A model-based controller is proposed which achieves active damping and output voltage regulation. A main feature of this controller is that it has an estimation scheme that deals with power change conditions under a constant output voltage. Numerical simulations are presented to evaluate the closed-loop performance.