Abstract

Three-port DC-to-DC converters based on the SEPIC-boost circuit have gained remarkable attraction in standalone applications such as DC micro grids having PV panels as roof-tops in electric boats, electric and hybrid vehicles, LED driving circuits, telecommunication systems, and medical and industrial electronics devices. Such a combination of SEPIC-boost in a single converter eliminates the use of three separate DC-to-DC converters to charge the batteries and to supply power from the PV module or batteries to the load. All such modes of operation in a single package make the converter compact by reducing the number of solid-state devices and passive components. It also enables the reduction in conversion losses and hence improves the system’s overall conversion efficiency. The control of a single circuit becomes simple and effective in terms of power management by detecting the solar irradiation and state of charge (SOC) of the battery. It enables the continuous flow of power to the load from PV modules or batteries, which is determined by the SOC of the battery and the available level of solar irradiation. This article develops the dynamic or state-space modeling of the combined operation of the SEPIC-boost-based DC-to-DC converter, which has not yet been developed in the literature. The development of systems based on separate dynamic SEPIC or boost modeling cannot meet the requirements of all operating modes. A state-space model of the combined operation of the SEPIC-boost converter enables evaluating the performance of such an energy management system during its various operating modes effectively. The validity of the developed model is recognized with results gained from MATLAB/Simulink and electronics-based Multisim computer software.

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