The authors propose a novel step-up converter with stackable switching stages that is suitable for renewable energy applications. On the one hand, the converter gain corresponds to that of the traditional quadratic boost converter, achieving an arbitrary exponential gain in extended configurations. On the other hand, the proposed converter requires a single switch, while the output voltage is partitioned among several capacitors. As argued in this work, the features of the proposed topology represent a significant contribution with respect to standard topologies that exhibit greater voltage stress. The operation principle and the main characteristics of the proposed converter are validated with experimental results.

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SUMMARYA small commercial wind-electric battery-charging system based on a three-bladed rotor has been analysed in a detailed fashion. The system consists of a synchronous generator with permanent magnets, a six-pulse rectifier and a battery bank with charge controller. A steady-state power curve is predicted based on the electric characteristics found experimentally and the aerodynamic performance of the rotor simulated with a version of blade element momentum (BEM) theory developed in our group. The BEM code has been designed to account for variable Reynolds numbers at different blade sections and stall conditions. The findings are compared with the manufacturer's specifications, and a detailed discussion is provided. A very good agreement with the steady-state power curve given by the manufacturer has been obtained after accounting for different sources of power losses, such as voltage drops in the rectifier, Joule heating in the power cables and losses in the generator's core. The system is found to operate near the aerodynamic optimum for all wind speeds studied, whereas electrical losses are significant near rated power. Some recommendations for improving the system performance are provided.

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This article proposes an arc stability index for Electrical Arc Furnaces (EAF) based on the real-time processing of the line to ground three-phase voltage measurements typically available at the secondary side of the EAF's power transformer. This methodology uses the definition of a virtual neutral for the open delta connection to calculate the neutral to ground voltage waveform and its Root Mean Square value that can be considered in a simple formula as stability indicator of the arc itself and for the power delivery to the arc. This proposed stability indicator may be used for process monitoring and power control.