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This paper addresses the analysis and experimental validation in steady state of a non-isolated quadratic buck converter to which an LC input filter has been added. This modification ensures that the power source is continually connected and delivering power during each switching period, which yields a reduction of switching components at the input. This may even entail a time-continuous input current. Continuous input current is a desired requirement for sensitive electric power sources and electric storage systems. The space-state model of the converter and the dynamical analysis of the open-loop linearized model are presented. Steady-state analysis is also presented that allows obtaining expressions for switching ripples and average values and conditions for boundary conduction mode operation. Experimental results, performed in a laboratory prototype of the converter, are included to verify the presented analysis.

In this paper the experimental validation of the open-loop operation for a buck converter with an LCLC filter at the output is addressed. This DC-DC buck converter has a significant reduction of output switching ripples and an increase of power density compared to the buck conventional topology. Moreover as passive components are less demanding, the implementation may be performed by using film capacitors. Hence the converter mean time failures can be made higher than for the conventional buck converter. These features can be applied in efficient renewable electric energy systems, in sensitive power sources and in sensitive loads. In this paper it is shown that by adequately selecting the passive elements, the open-loop oscillating behaviors may be highly alleviated which makes of the converter a suitable solution. Experimental results are presented to show the performance of the converter.

This paper models and proposes a controller for a modified quadratic buck converter where the input inductance has been replaced by an LC filter. The voltage conversion ratio of this converter is equivalent to two conventional buck converters in cascade and has only one active switching device. Due to the LC input filter, the high-frequency switching components are reduced at the input and this may entail even a time continuous input current as is shown in this paper. A controller is also proposed to regulate the output voltage to a given reference. Continuous input current is a requirement for sensitive electric power sources such as such as fuel cells, batteries and electrolytic capacitors used at DC-links in power electronics applications. The proposed controller provides damping to the closed-loop system. Numerical simulations are presented to evaluate the closed-loop performance.