We introduce a new dc-dc converter topology with the following features: first, quadratic voltage gain, which allows the converter to work over a wide voltage range with a minimal variation of duty cycle and without the use of extreme duty cycles; second, output voltage ripple mitigation, which can be accomplished with respect to a fixed but otherwise arbitrary duty cycle by proper selection of components and switching signals. Since the proposed converter can be designed to have zero output voltage ripple for the nominal gain (duty cycle), this allows the use of small values of capacitances. The underlying principles and steady-state equations in continuous conduction mode are presented in detail. Experimental tests are presented to validate the analysis.

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.

Phase-locked loop (PLL) systems play a crucial role in grid synchronization. Since variations on the grid voltage parameters are in general uncertain, the dynamics of PLLs are by nature nonlinear. This fact imposes a relevant challenge to guarantee their stability. Unfortunately, as argued in this paper, there is a remarkable lack of global stability tests even for the most common approaches, such as the synchronous reference frame (SRF). In this case, there is only available a small-signal—linearized—model-based approach to stability. The main issue of resorting to local conclusions is that synchronization is forced to operate under conservative conditions, where large-signal variations are forbidden. Needless to say, this has a detrimental impact on applications, since performance is limited by small disturbance assumptions. Motivated by this problem, in the present work, we provide global asymptotic stability tests for two fundamental PLL algorithms. Namely, the conventional SRF-PLL and the enhanced SRF-EPLL. To do so, we use a Lyapunov approach acting directly on nonlinear trajectories. Consequently, the provided stability proofs do not rely on any linearization technique, frequency-domain conversion, or small-signal model representation. The main contribution in this paper is a set of stability conditions that are valid in a global sense. Moreover, it is shown that these results have direct practical implications in the form of new robust PLL gain tuning guidelines.

The increasing interest in renewable energy sources has brought attention to large voltage-gain dc–dc converters; among the different available solutions to perform a large voltage-gain conversion, this article presents an overview of non-isolated dc–dc converter topologies that utilize switched-capacitor circuits, i.e., diode-capacitors voltage multipliers. The review includes combinations of a traditional power stage with a diode-capacitor-based voltage multiplier, such as the multilevel boost converter. This article starts by reviewing switched-capacitor (SC) circuits, different topologies, and different types of charge exchange; it provides a straightforward analysis to understand the discharging losses. It then covers the multilevel boost converter and other topologies recently introduced to the state-of-the-art. Special attention is put on SC circuits with resonant charge interchange that have recently been probed to achieve very good efficiency. An additional contribution of the article is new proof of the discharging losses in resonant switched-capacitor circuits focused on the initial and final stored energy in capacitors, and this proof explains the relatively large efficiency obtained with SC resonant converters.