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Currently, the urgent needs of sustainable mobility and green energy generation are driving governments and researchers to explore innovative energy storage systems. Concurrently, lithium-ion batteries are one of the most extensively employed technologies. The challenges of battery modeling and parameter estimation are crucial for building reliable battery management systems that ensure optimal battery performance. State of charge (SOC) estimation is particularly critical for predicting the available capacity in the battery. Many methods for SOC estimation rely on the knowledge of the open-circuit voltage (OCV) curve. Another significant consideration is understanding how these curves evolve with battery degradation. In the literature, the effect of cycle aging on the OCV is primarily addressed through the look-up tables and correction factors applied to the OCV curve for fresh cells. However, the variation law of the OCV curve as a function of the battery cycling is not well-characterized. Building upon a simple analytical function with five parameters proposed in the prior research to model the OCV as a function of the absolute state of discharge, this study investigates the dependency of these parameters on the moved charge, serving as an indicator of the cycling level. Specifically, the analysis focuses on the impact of cycle aging in the low-, medium-, and high-SOC regions. Three different cycle aging tests were conducted in these SOC intervals, followed by the extensive experimental verification of the proposed model. The results were promising, with mean relative errors lower than 0.2% for the low- and high-SOC cycling regions and 0.34% for the medium-SOC cycling region. Finally, capacity estimation was enabled by the model, achieving relative error values lower than 1% for all the tests. [ABSTRACT FROM AUTHOR]

Power-like functions based on Tellegen's theorem are important tools in the study of electrical networks. Networks containing power converters are nonlinear and/or time-variant. This fact continues to represent a challenge regarding both theoretical analysis and practical application. The topologies of existing converters are multiform and there is not one single general approach to them. In terms of circuit theory, a number of theorems regarding ideal switching can be derived. This paper proposes a novel power-like function to describe the switching phenomenon and thus contribute to principles underlying power converters. Specifically, it sets out theorems and describes certain empirical applications which clearly work in practice but for which no formal proof has yet been provided. It focuses in detail on hard commutation of switches and formulates a principle of correlation between active (i.e. externally fired) and passive hard switching. The paper concludes by presenting examples of applications in support of the theoretical results. [ABSTRACT FROM AUTHOR]

Today's residential battery energy storage systems (BESSs) are off the shelf products used to increase the self‐consumption of residential photovoltaic (PV) plants and to reduce the losses related to energy transfer in distribution grids. This work investigates the economic viability of adding a BESS to a residential grid‐connected PV plant by using a methodology for optimising the size of the BESS. The identification of the optimal size which minimises the total cost of the system is not trivial; indeed, it is a trade‐off between OPEX and CAPEX, which are mainly affected by the battery technology, usage profile, expected lifetime, and efficiency. Here, an analysis of the opportunity to install a storage system together with a grid‐connected residential PV plant is performed. Three typical low‐voltage prosumers (Italy, Switzerland, and the UK) are investigated in order to take into account the different legislative and tariff framework over Europe. Numerical results reported here show that present costs of storages are still too high to allow an economic convenience of the storage installation. Moreover, an indication of the necessary incentives to allow the spreading of these systems is given. [ABSTRACT FROM AUTHOR]

Three-phase to three-phase power conversion with variable frequency and output voltage amplitude control can be realized with both matrix converter and indirect matrix converter configurations. Even if this two power converters have a different topology, the indirect configuration provides an equivalent circuit widely used to define matrix converter modulation strategies. The equivalence between the states of the two converters is well known but a discussion on indirect matrix converter relationships has never been deeply investigated. This paper discusses the equivalence between the two power converter configurations from a mathematical viewpoint, pointing out the intrinsic characteristics and potentialities of each of them. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are a key technology for current and future energy storage in mobile and stationary application. In particular, they play an important role in the electrification of mobility and therefore the battery lifetime prediction is a fundamental aspect for successful market introduction. Numerous studies developed ageing models capable of predicting battery life span. Most of the previous works compared the effect of the ageing factors to a battery's cycle life. These cycles are identical, which is not the case for electric vehicles applications. Indeed, most of the available information is based on results from laboratory testing, under very controlled environments, and using ageing protocols, which may not correctly reflect the actual utilization. For this reason, it is important to link the effect of duty cycles with the ageing of the batteries. This paper proposes a simple method to investigate the effect of the duty cycle on the batteries lifetime through tests performed on different cells for different kinds of cycle. In this way, a generic complex cycle can be seen as a composition of elemental cycles by means of Rainflow procedures. Consequently, the ageing due to any cycle can be estimated starting from the knowledge of simpler cycles.