The major consideration in dc-dc conversion is often associated with high efficiency, reduced stresses involving semiconductors, low cost, simplicity and robustness of the involved topologies. In the last few years, high-step-up nonisolated dc-dc converters have become quite popular because of its wide applicability, especially considering that dc-ac converters must be typically supplied with high dc voltages. The conventional non-isolated boost converter is the most popular topology for this purpose, although the conversion efficiency is limited at high duty cycle values. In order to overcome such limitation and improve the conversion ratio, derived topologies can be found in numerous publications as possible solutions for the aforementioned applications. Within this context, this work intends to classify and review some of the most important non-isolated boost-based dc-dc converters. While many structures exist, they can be basically classified as converters with and without wide conversion ratio. Some of the main advantages and drawbacks regarding the existing approaches are also discussed. Finally, a proper comparison is established among the most significant converters regarding the voltage stress across the semiconductor elements, number of components and static gain.
The generation of electricity from photovoltaic (PV) arrays has been increasingly considered as a prominent alternative to fossil fuels. However, the conversion efficiency is typically low and the initial cost is still appreciable. A required feature of a PV system is the ability to track the maximum power point (MPP) of the PV array. Besides, MPP tracking (MPPT) is desirable in both grid-connected and stand-alone photovoltaic systems because the solar irradiance and temperature change throughout the day, as well as along seasons and geographical conditions, also leading to the modification of theI×V(current versus voltage) andP×V(power versus voltage) curves of the PV module. MPPT is also justified by the relatively high cost of the energy generated by PV systems if compared with other sources. Since there are various MPPT approaches available in the literature, this work presents a comparative study among four popular techniques, which are the fixed duty cycle method, constant voltage (CV), perturb and observe (P&O), and incremental conductance (IC). It considers different operational climatic conditions (i.e., irradiance and temperature), since the MPP is nonlinear with the environment status. PSIM software is used to validate the assumptions, while relevant results are discussed in detail.
High voltage step-up is necessary in several applications, especially considering that dc-ac converters must be supplied by high dc voltages. The conventional boost converter is the most popular topology for this purpose, although the conversion efficiency is limited at high duty cycle values. In order to overcome such limitation and improve the conversion ratio, many converter topologies have been proposed so far. Within this context, this work intends to review some of the most important works regarding boost-based dc-dc converters. Some structures are covered and classified basically as converters with and without wide conversion ratio. Some of the main advantages and drawbacks regarding the existing approaches are also discussed. Finally, a proper comparison is established among the most significant converters regarding the voltage stress across the semiconductor elements, number of components, and static gain.
High power factor rectifiers have been consolidated as an effective solution to improve power quality indices in terms of input power factor correction, reduction in the total harmonic distortion of the input current and also regulated dc voltages. Within this context, this subject has motivated the introduction of numerous converter topologies based on classic dc-dc structures associated with novel control techniques, thus leading to the manufacturing of dedicated integrated circuits that allow high input power factor by adding a front-end stage to switch-mode converters. In particular, boost converters in continuous current mode (CCM) are widely employed since they allow obtaining minimised electromagnetic interference levels. This work is concerned with a literature review involving relevant ac-dc single-phase boost-based topologies with high input power factor. The evolution of aspects regarding the conventional boost converter is shown in terms of improved characteristics inherent to other ac-dc boost converters. Additionally, the work intends to be a fast and concise reference to single-phase ac-dc boost converters operating in CCM for engineers, researchers and experts in the field of power electronics by properly analysing and comparing the aforementioned rectifiers.
When dealing with power factor correction (PFC) rectifiers that require the use of high filter capacitances, conventional small-signal modelling techniques are not capable of reproducing the converter behaviour accurately owing to the impact of the low-frequency dynamics on the system. In this context, this work presents an improved modelling technique applied to a conventional PFC boost converter operating in continuous conduction mode (CCM). The proposed approach leads to a more accurate analysis than the traditional modelling developed for dc-dc converters, which is often extended to rectifiers. It consists of a fast and concise solution for the implementation of several PFC techniques from the derived transfer functions. The introduced method is described aiming at the development of a boost-based PFC stage using the well-known one-cycle control technique (OCC). Simulation and experimental results are presented and thoroughly discussed to validate the theoretical assumptions. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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