Open Access
High frequency power transformers with foil windings: maximum interleaving and optimal design
(IEEE, 2015) Barrios Rípodas, Ernesto; Urtasun Erburu, Andoni; Ursúa Rubio, Alfredo; Marroyo Palomo, Luis; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Foil conductors and primary and secondary interleaving are normally used to minimize winding losses in high frequency transformers used for high-current power applications. However, winding interleaving complicates the transformer assembly, since taps are required to connect the winding sections, and also complicates the transformer design, since it introduces a new tradeoff between minimizing losses and reducing the construction difficulty. This paper presents a novel interleaving technique, named maximum interleaving, that makes it possible to minimize the winding losses as well as the construction difficulty. An analytical design methodology is also proposed in order to obtain free cooled transformers with a high efficiency, low volume and, therefore, a high power density. For the purpose of evaluating the advantages of the proposed maximum interleaving technique, the methodology is applied to design a transformer positioned in the 5 kW 50 kHz intermediate high frequency resonant stage of a commercial PV inverter. The proposed design achieves a transformer power density of 28 W/cm3 with an efficiency of 99.8%. Finally, a prototype of the maximum-interleaved transformer is assembled and validated satisfactorily through experimental tests.
Open Access
Dynamic modeling of a pressurized alkaline water electrolyzer: a multiphysics approach
(IEEE, 2023) Iribarren Zabalegui, Álvaro; Elizondo Martínez, David; Barrios Rípodas, Ernesto; Ibaiondo, Harkaitz; Sánchez Ruiz, Alain; Arza, Joseba; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper a dynamic model for the simulation of pressurized alkaline water electrolyzers is presented. The model has been developed following a multiphysics approach, integrating electrochemical, thermodynamic, heat transfer and gas evolution processes in order to faithfully reproduce the complete dynamical behavior of these systems. The model has been implemented on MATLAB/Simulink and validated through experimental data from a 1 Nm3/h commercial alkaline water electrolyzer. Validations have been performed under real scenarios where the electrolyzer is working with power profiles characteristic from renewable sources, wind and photovoltaic. The simulated results have been found to be consistent with the real measured values. This model has a great potential to predict the behavior of alkaline water electrolyzers coupled with renewable energy sources, making it a very useful tool for designing efficient green hydrogen production systems.
Open Access
Onset of irreversible reactions in overcharging lithium-ion cells: an experimental and modeling approach
(IEEE, 2023) Irujo Izcue, Elisa; Berrueta Irigoyen, Alberto; Lalinde Sainz, Iñaki; Arza, Joseba; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Lithium-ion batteries are energy storage systems used in an increasing number of applications. Due to their flammable materials, their use entails risks of fire and explosion. The study of the abuse operation of these batteries before reaching the thermal runaway is a relevant research topic to prevent safety issues. There are various studies in the bibliography providing exhaustive thermal studies of the safe operating area, as well as concerning the thermal runaway. However, the onset irreversible reactions, that take place at a SOC around 110%, have not been properly analyzed. We present in this contribution an experimental study of this onset reaction measured in pouch Li-ion cells under various conditions of charge current and temperature. We also propose a lumped-parameter thermal model for the cell, which allows a detailed characterization of this exothermic reaction. The results achieved in this contributions can be a key tool to prevent overcharge accidents that may arise due to malfunctioning of the battery charger or battery management system.
Open Access
Characterization and capacity dispersion of lithium-ion second-life batteries from electric vehicles
(IEEE, 2019) Braco Sola, Elisa; San Martín Biurrun, Idoia; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua
Nowadays, electric vehicle batteries reutilization is considered such as a feasible alternative to recycling, as it allows to benefit from their remaining energy and to enlarge their lifetime. Stationary applications as self-consumption or isolated systems support are examples of possible second life uses for these batteries. However, the modules that compose these batteries have very heterogeneous properties, and therefore condition their performance. This paper aims to characterize and analyze the existing capacity dispersion of Nissan Leaf modules that have reached the end of their lifetime on their original application and of new modules of this Electric Vehicle, in order to establish a comparison between them.
Open Access
Influence of the power supply on the energy efficiency of an alkaline water electrolyser
(Elsevier, 2009) Ursúa Rubio, Alfredo; Marroyo Palomo, Luis; Gubía Villabona, Eugenio; Gandía Pascual, Luis; Diéguez Elizondo, Pedro; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza; Química Aplicada; Kimika Aplikatua; Gobierno de Navarra / Nafarroako Gobernua
Electric energy consumption represents the greatest part of the cost of the hydrogen produced by water electrolysis. An effort is being carried out to reduce this electric consumption and improve the global efficiency of commercial electrolysers. Whereas relevant progresses are being achieved in cell stack configurations and electrodes performance, there are practically no studies on the effect of the electric power supply topology on the electrolyser energy efficiency. This paper presents an analysis on the energy consumption and efficiency of a 1 N m3 h1 commercial alkaline water electrolyser and their dependence on the power supply topology. The different topologies of power supplies are first summarised, analysed and classified into two groups: thyristor-based (ThPS) and transistor-based power supplies (TrPS). An Electrolyser Power Supply Emulator (EPSE) is then designed, developed and satisfactorily validated by means of simulation and experimental tests. With the EPSE, the electrolyser is characterised both obtaining its I–V curves for different temperatures and measuring the useful hydrogen production. The electrolyser is then supplied by means of two different emulated electric profiles that are characteristic of typical ThPS and TrPS. Results show that the cell stack energy consumption is up to 495 W h N m3 lower when it is supplied by the TrPS, which means 10% greater in terms of efficiency.
Open Access
Incremental capacity analysis of lithium-ion second-life batteries from electric vehicles under cycling ageing
(IEEE, 2021) Braco Sola, Elisa; San Martín Biurrun, Idoia; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Nowadays, the reuse of batteries from electric vehicles is considered a promising solution to benefit from their remaining energy and extend their lifespan. Yet, the economic viability of these second-life batteries is still uncertain, and the optimization of testing at their reconfiguration stage and during their lifetime is the key to ensure their success. This paper aims to assess Incremental Capacity Analysis technique in Nissan Leaf modules during their second-life use, in order to evaluate both its potential as an State of Health estimator and as a tool to identify underlying degradation mechanisms. Despite the different internal state and ageing rates observed between the tested modules, ICA is found to be consistent at similar SOH levels. The influence of ageing, current and temperature on ICA is evaluated through an accelerated cycling test. Results show that ICA is a promising alternative to estimate SOH during second life even at currents up to C/2 and testing temperatures of 45 °C. However, testing by accelerated currents and temperatures is not recommended for the identification of degradation mechanisms.
Open Access
Electro-thermal modelling of a supercapacitor and experimental validation
(Elsevier, 2014) Berrueta Irigoyen, Alberto; San Martín Biurrun, Idoia; Hernández, Andoni; Ursúa Rubio, Alfredo; Sanchis Gúrpide, Pablo; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua
This paper reports on the electro-thermal modelling of a Maxwell supercapacitor (SC), model BMOD0083 with a rated capacitance of 83 F and rated voltage of 48 V. One electrical equivalent circuit was used to model the electrical behaviour whilst another served to simulate the thermal behaviour. The models were designed to predict the SC operating voltage and temperature, by taking the electric current and ambient temperature as input variables. A five-stage iterative method, applied to three experiments, served to obtain the parameter values for each model. The models were implemented in MATLABSimulink , where they interacted to reciprocally provide information. These models were then validated through a number of tests, subjecting the SC to different current and frequency profiles. These tests included the validation of a bank of supercapacitors integrated into an electric microgrid, in a real operating environment. Satisfactory results were obtained from the electric and thermal models, with RMSE values of less than 0.65 V in all validations.
Open Access
Identification of critical parameters for the design of energy management algorithms for Li-ion batteries operating in PV power plants
(IEEE, 2020) Berrueta Irigoyen, Alberto; Soto Cabria, Adrián; Marcos Álvarez, Javier; Parra Laita, Íñigo de la; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, ReBMS PJUPNA1904; Gobierno de Navarra / Nafarroako Gobernua, 0011-1411-2018-000029 GERA
Lithium-ion batteries are gaining importance for a variety of applications due to their price decrease and characteristics improvement. For a proper use of such storage systems, an energy management algorithm (EMA) is required. A number of EMAs, with various characteristics, have been published recently, given the diverse nature of battery problems. The EMA of deterministic battery problems is usually based on an optimization algorithm. The selection of such an algorithm depends on a few problem characteristics, which need to be identified and closely analyzed. The aim of this article is to identify the critical optimization problem parameters that determine the most suitable EMA for a Li-ion battery. With this purpose, the starting point is a detailed model of a Li-ion battery. Three EMAs based on the algorithms used to face deterministic problems, namely dynamic, linear, and quadratic programming, are designed to optimize the energy dispatch of such a battery. Using real irradiation and power price data, the results of these EMAs are compared for various case studies. Given that none of the EMAs achieves the best results for all analyzed cases, the problem parameters that determine the most suitable algorithm are identified to be four, i.e., desired computation intensity, characteristics of the battery aging model, battery energy and power capabilities, and the number of optimization variables, which are determined by the number of energy storage systems, the length of the optimization problem, and the desired time step.
Open Access
Influence of renewable power fluctuations on the lifetime prediction of lithium-ion batteries in a microgrid environment
(IEEE, 2019) Soto Cabria, Adrián; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua
This contribution analyses lifetime estimation errors due to the effect of power fluctuations in lithium-ion batteries connected to microgrids when different time steps are used for the calculations. Usually, not every second data are available or the computational cost is excessively high. Those facts result in the use of larger time steps. However, the increase of the time steps may turn out in too optimistic predictions. Data from a real microgrid make it possible to optimize calculation times while keeping low errors. The results show that when 1 minute time step is set, the computation time is reduced by 14.4 times while the lifetime overstatement is only 3.5-5.2% higher, depending on the aging model.
Open Access
Applied method to model the thermal runaway of lithium-ion batteries
(IEEE, 2021) Lalinde Sainz, Iñaki; Berrueta Irigoyen, Alberto; Sanchis Gúrpide, Pablo; Ursúa Rubio, Alfredo; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The thermal runaway (TR) is one of the most dangerous phenomena related to lithium-ion batteries. For this reason, there are different proposals in the literature for its modelling. Most of these proposed models take into account the decomposition reactions between the internal components of the cell, and base the adjustment of the parameters on numerous abuse tests that lead to the appearance of TR. However, these tests are destructive, require specific equipment, present a high economic cost and are very time consuming. This paper proposes a modelling method which enables the development of TR models with the use of fewer resources. This method is based on chemical kinetics, which allow a simplification of the general modelling process published in the literature. At the same time it maintains good accuracy and makes it possible to define the TR behavior of any type of cell, regardless of its chemistry, shape or size. Furthermore, the proposed method allows the use of the experimental results most commonly presented in the specialized literature, which significantly reduces the need for destructive testing. The presented modelling method achieves a good compromise between accuracy and applicability in the validations shown in the paper.