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.

This study presents the analysis, design and experimental evaluation of a high-voltage gain dc-dc converter applied to photovoltaic (PV) systems. A PV module rated at 17 V is connected to the input side, whereas the converter is responsible for stepping the voltage up to 311 V with the achievement of maximum power point tracking (MPPT). An experimental prototype rated at 100 W is implemented, which does not employ electrolytic capacitors, thus increasing the useful life of the arrangement and also allowing the incorporation of the converter to the PV module. Prominent advantages of the topology are low cost and simplicity in terms of the MPPT algorithm and the system implementation, which are mandatory characteristics for renewable energy applications.

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The need for solid-state ac-dc converters to improve power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input ac mains, and precisely regulated dc output have motivated the proposal of several topologies based on classical converters such as buck, boost, and buck-boost. Additionally, novel control techniques dedicated to PFC have also been introduced, motivating the manufacturing of commercial integrated circuits to impose sinusoidal currents in the front-end stage of switch-mode converters. Boost converters operating in continuous current mode (CCM) have become particularly popular because reduced electromagnetic interference (EMI) levels result from its utilization. Within this context, this work deals with a comprehensive review of some of the most relevant ac-dc singlephase boost converters for PFC applications. The evolution of the conventional boost converter is demonstrated in terms of improved characteristics achieved by other boost-based topologies. Besides, it seeks to establish a fast and concise guide on ac-dc boost converters to researchers and experts in power electronics by comparing the topologies.

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