Sepic and Cuk power converters working as power factor preregulators (PFP) in the discontinuous conduction mode (DCM) present the following desirable characteristics for a PFP: (1) the power converter works as a voltage follower (no current loop is needed); (2) the theoretical power factor is unity; and (3) the input current ripple is defined at the design stage. Besides, input-output galvanic isolation is easily obtained. This paper analyzes the operation of both power converters as DCM-PFP. Design equations are derived, as well as a small-signal model to aid the control loop design. Both simulation and experimental results are presented that are in agreement with the theoretical analysis and complement the work.

SEPIC and Cuk converters present a great advantage over boost and fly-back topologies in discontinuous conduction mode (DCM): an input current with low harmonic content can be obtained by correctly choosing the inductors L/sub 1/ and L/sub 2/ of the converter with a fixed operation frequency, as is demonstrated here. The authors also discuss the intermedium capacitor C/sub 1/ as well as some advantages and disadvantages of the application. Simulation and experimental results support the approach. It is concluded that SEPIC and Cuk converters in DCM seem to be good choices for use as power factor preregulators.

This paper presents a modeling approach to obtain a small-signal model for a single-switch single-phase and three-phase discontinuous boost high-power-factor rectifiers. Such converters present nonlinear characteristics, and an approximation of them is used to derive the models. The most important result obtained is that the small-signal output impedance is not equal to the load impedance. The analysis is validated by experimental results.

This paper was performed to identify the parameters of the photovoltaic module using Differential Evolution. The Differential Evolution is a search technique based on mechanisms of natural selection and genetics. Some of the advantages of Differential Evolution are: the speed of convergence and ease of implementation. The data used to identify the parameters of the photovoltaic were obtained by essay or provided of manufacturers' datasheets. The Matlab ^® was used to identify the parameters for the Differential Evolution and simulation model of the photovoltaic module.