Noshin Omar

Accurate modeling of the nonlinear relationship between the open circuit voltage (OCV) and the state of charge (SOC) is required for adaptive SOC estimation during the lithium-ion (Li-ion) battery operation. Online SOC estimation should meet several constraints, such as the computational cost, the number of parameters, as well as the accuracy of the model. In this paper, these challenges are considered by proposing an improved simplified and accurate OCV model of a nickel manganese cobalt (NMC) Li-ion battery, based on an empirical analytical characterization approach. In fact, composed of double exponential and simple quadratic functions containing only five parameters, the proposed model accurately follows the experimental curve with a minor fitting error of 1 mV. The model is also valid at a wide temperature range and takes into account the voltage hysteresis of the OCV. Using this model in SOC estimation by the extended Kalman filter (EKF) contributes to minimizing the execution time and to reducing the SOC estimation error to only 3% compared to other existing models where the estimation error is about 5%. Experiments are also performed to prove that the proposed OCV model incorporated in the EKF estimator exhibits good reliability and precision under various loading profiles and temperatures.

Dit artikel beschrijft de performanties van een aantal commerciële lithium-ion batterijen voor gebruik in batterij aangedreven voertuigen zoals lithium-ijzerfosfaat (LFP), lithium-nikkel-mangaan-kobaltoxide (NMC), lithium-nikkelmangaan-aluminiumoxide en lithium-titanaatoxide (LTO) in de negatieve elektrode. In de analyse, worden de meest relevante parameters voorgesteld die een impact hebben op de batterijperformanties. Zo ziet men dat NMC batterijen een aanzienlijke hoge energiedichtheid hebben (120 - 160 Wh/kg) tegenover 70 – 110 Wh/kg voor LFP, 90 Wh/kg voor NCA en 70 Wh/kg voor LTO. Maar bij lage temperaturen (-18°C) blijken dan weer de LFPs en LTOs over de beste karakteristieken te beschikken. Daarnaast, hebben deze laatste batterijtechnologieën een betere levensduurprestatie (ongeveer 2000 cycli voor LFP en 5000 cycli voor LTO). In het artikel worden tevens de algemene karakteristieken van deze batterijen weergegeven op het vlak van state of charge estimatie, oplaadprestaties ...

The following article will analyze the benefits of hybridizing the drivetrain of a diesel bus with a lithium ion capacitor based rechargeable energy storage system. The high power capability and high energy density of LICs compared to Electrical Double-Layer Capacitors make them an interesting candidate for usage as a peak power system in a hybrid bus. A backwards simulation program is developed in order to model the drivetrain of the hybrid bus and the moving average power control strategy is implemented to manage the power flows within the drivetrain. As a case study, a demonstrator bus of De Lijn is modelled and the performance is analysed by following the Millbrook London Transport Bus Cycle, which resulted in a consumption of 32,4l/100km.

ABSTRACT Due to the wide applications of lithium-ion capacitors (LiCs) in various fields and due to the lack of comprehensive study regarding LiC modeling, there is a need for an accurate electrical model, which can predict the LiC's behavior at different load conditions. Characterization helps better understanding of investigated energy storage system and reveals its functioning range, linear and nonlinear variations and also its limits. As the electrochemical based energy storages are non-linear, the presented model should be linearized in the range of the specific application. Therefore the identification procedures should be performed under various conditions as needed. Results from hybrid pulse power characterization (HPPC) test have been used for the system identification of LiC in the time domain. Since system identification in the time domain cannot provide a complete map of variation of model parameters, a wide range frequency impedance spectroscopy (10 kHz–20 mHz) and at various conditions such as current, state of charge (SoC) levels and temperatures has been performed in order to identify the parameters of assumed model in the frequency domain, which is an unique analysis and never has been performed for lithium ion capacitors. The used model has been chosen based on probable chemical reactions, which occur within a specific frequency range. Frequency domain analysis can identify model variation, which is not possible in time domain identification. In this paper a new identification approach has been introduced based on combination of time and frequency domains. Based on proposed method, identification process in frequency domain helps to identify parameters which are not variable in function of current and SoC variations. Therefore the mentioned parameters can be withdrawn from the cost function in the time domain and it improves the performance of system identification procedure. The proposed method improves the model accuracy around 2% at time domain and around 5% at frequency domain.

The increased activity in the field of Battery Electric Vehicles (BEVs) and Hybrid Electric Vehicles (HEVs) have led to an increase in standardization work, performed by both world-wide organizations like the IEC or the ISO, as by regional and national bodies such as CEN, CENELEC, SAE or JEVA. The issues of these standards cover several topics: safety, performance and operational/dimension issues. This paper reports a brief overview of current standardization activities of lithium batteries based on IEC 62660-1/2 and ISO 12405-1/2. Furthermore, in this paper, a series of innovative test procedures for lithium-ion batteries are presented. Thanks to these tests, the general characteristics of a battery such as charge and discharge capabilities, power performances and life cycle can be determined. Then, a new approach for extracting the life cycle of a battery in function of depth of discharge has been developed.

The Integrated Project “Batteries 2020” unites 9 European partners jointly working on the research and development of European competitive automotive batteries. The project aims at increasing lifetime and energy density of large format high-energy lithium-ion batteries towards the goals targeted for automotive batteries. Three parallel strategies will be followed in order to achieve those targets: (i) Highly focused materials development; two improved generations of NMC materials will allow the performance, stability and cyclability of state of the art cells to be improved. (ii) Understanding ageing phenomena; a realistic approach will be carried out towards the development of a robust testing methodology which will be improved in several steps. Combined accelerated, real tests, real field data, post-mortem, modeling and validation with real driving profiles will provide a thorough understanding of degradation processes. (iii) Reduction of battery cost; a way to reduce costs, increa...

Conference code: 93692, Export Date: 19 January 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Omar, N.; Vrije Universiteit Brussel, IR-ETEC, Pleinlaan 2, B-1050, Elsene, Belgium; email: noshomar@vub.ac.be, References: Bockris, J.O.M., Conway, B.E., Yeager, E., White, R.E., Comprehensive treatise electrochemistry ISBN 0306-40590-3, , New York;

In this paper, an extended analysis of the performance of different hybrid Rechargeable Energy Storage Systems (RESS) for use in Plug-in Hybrid Electric Vehicle (PHEV) with a series drivetrain topology is analyzed, based on simulations with three different driving cycles. The investigated hybrid energy storage topologies are an energy optimized lithium-ion battery (HE) in combination with an Electrical Double-Layer Capacitor (EDLC) system, in combination with a power optimized lithium-ion battery (HP) system or in combination with a Lithium-ion Capacitor (LiCap) system, that act as a Peak Power System. From the simulation results it was observed that hybridization of the HE lithium-ion based energy storage system resulted from the three topologies in an increased overall energy efficiency of the RESS, in an extended all electric range of the PHEV and in a reduced average current through the HE battery. The lowest consumption during the three driving cycles was obtained for the HE-Li...

In this paper an extensive overview of different state-of-the arts models, created to simulate the behavior of lithium ion batteries, will be presented. A new classification of different types of models is proposed, which includes models ranging from electrochemical, electrical, thermal and mechanical models. A new classification system, depending on the method the inputs are related to the outputs (i.e. empirical, semi-empirical and physical modeling) is used to distinguish between the large varieties of available models and to classify these models in a structured way. Further, a distinction is made based on the timescale of the modeling. In this way, it is clear if the model in casu is suitable to give information on the short-term behavior or on the long-term behavior of the battery. Finally, the different electrical models, suitable for lithium ion batteries, will be analyzed and compared with special attention to the performance of the different models for simulating the dynam...

Dit artikel bespreekt de verouderingsparameters van lithium-ijzerfosfaat batterijen, en onderzoekt de invloed van laad- en ontlaadstroom, omgevingstemperatuur en ontlaaddiepte op de performanties van dit type batterij. Uit deze analyse komt ondermeer voort dat de performantie van de batterij bij verhoogde temperatuur (40°C en meer) lager is dan bij kamertemperatuur (c.a. 25°C). Bovendien kunnen de optredende verschijnselen niet beschreven worden door de gekende wet van Arrhenius toe te passen om de levensduur van dit type batterij te bepalen bij een bepaalde temperatuur, vertrekkende vanaf gekende gegevens voor een andere temperatuur. V ervolgens werden een aantal levenscyclustesten uitgevoerd om de langetermijnperformanties van de batterijcellen te onderzoeken bij verschillende constante ontlaadstromen. De bekomen resultaten laten de negatieve impact zien van hoge ontlaadstromen op de karakteristieken van de batterij. Verder laten levenscyclustesten bij verschillende ontlaaddiepte ...

Lithium-ion capacitors (LIC) are a new type of hybrid energy storage devices that combine the characteristics of electrical double-layer capacitors and lithium-ion battery technology. The electrical and thermal performances of a 1500F LIC cell developed by JM Energy have been examined. It was observed that the investigated cell has an energy density of 11,0Wh/kg and a matched impedance specific power of 9,3kW/kg. Additionally, it was observed that the capacity of the LIC decreased in function of the discharge current, indicating that they are – like batteries - subjected to the Peukert phenomenon. From Electrochemical Impedance Spectroscopy measurements, it was defined that the AC impedance is 1,39mOhm. Based on the performed analyses; an electrical 1st order Thevenin model has been developed.

ABSTRACT This paper represents the calendar life cycle test results of a 7Ah lithium iron phosphate battery cell. In the proposed article and extended analysis has been carried out for the main aging parameters during calendar life and the associated impact of the used battery model. From the analysis, it has been showed that the impact of high temperatures and state of charge is harmful for the lifetime of the battery. Therefore, there is a need for having a dedicated control strategy for keeping the battery in the most appropriate operating condition. The FreedomCar battery model parameters have been analyzed during calendar life.

The introduction of new electricity storage components such as electric double-layer capacitors or lithium batteries creates the necessity for relevant and reliable standards to assess components' performance and safety. Technical committees within international standardization bodies such as IEC and ISO have thus increased the intensity of standardization work on the matter. The paper will describe current work on the matter, concentrating on the characteristic action points where standardization work is needed. ...

Abstract This paper represents a comprehensive comparison of three battery chemistries for use in plug-in battery electric vehicles: lithium iron phosphate oxide, lithium nickel manganese cobalt oxide and nickel cobalt aluminum oxide anodes. The battery characteristics at different temperature conditions have been investigated, using test procedures as defined in the standard IEC 62660-1/2 and introducing new load profiles. Main focus key parameters are the energy density, power capabilities, rate performances ...

ABSTRACT This paper is part of a research project, which aims to investigate the opportunities for using the second life batteries after their replacement from plug-in electric vehicles (PHEVs), hybrid electric vehicles (HEVs) and battery electric vehicles (EVs) for smart grid applications. Batteries which are used for vehicular service cannot be used once that the energy capacity becomes less than 70% - 80%. The remaining capacity of the battery can still be utilized for stationary applications such as powering a building during peak load hours and reducing the environmental pollution. Owner of an electric vehicle would be benefited if a market for the used batteries is established. These batteries are called second life batteries. In these applications, the power electronics converters (PECs) play an important role in the development of a high performance integrated system. It means that the performance of the second life batteries mainly depends on the characteristics of the PECs, which are utilized to achieve the integration of the second life batteries with the smart grid. Therefore, this paper presents a comparative evaluation of different multilevel DC/DC converter topologies that can be used to connect the second life batteries to smart grid. Furthermore, the advantages and drawbacks of the most popular multilevel DC/DC converter topologies are presented in detail. In this paper, a selected harmonic elimination (SHE) technique will be used to realize the control system of the multilevel DC/DC converter, and its influence on the performance of each battery module is analyzed. These topologies are designed and verified by using MATLAB/Simulink environment

The introduction of new electricity storage components such as electric double-layer capacitors or lithium batteries creates the necessity for relevant and reliable standards to assess components' performance and safety. Technical committees within international standardization bodies such as IEC and ISO have thus increased the intensity of standardization work on the matter. The paper will describe current work on the matter, concentrating on the characteristic action points where standardization work is needed. ...

ABSTRACT his paper deals with the electrical double-layer capacitor’s (EDLC) aging diagnosis for electric and hybrid vehicles. It has been shown in the literature that the aging of EDLCs is related to the constraints undergone by the component such as EDLC voltage (Vsc) combined with the operating temperature. The results of several studies show that the best indicators of the EDLCs aging are the capacitance and the equivalent series resistance. Some experimental methods allow the identification of these parameters but they are time consuming and cannot be embedded. This study presents a new method to estimate the EDLC parameters using least square algorithm based on data measurements of input/output of the system. In order to perform the aging test, a test bench is developed. EDLCs are aged at constant temperature and constant voltage. They are placed inside a climatic chamber at 70 ◦ C and polarized at 2.9 V during the aging process. To quantify the EDLC aging, the equivalent series resistance and the equivalent capacitance are measured.

ABSTRACT Battery performance and safety constitute a bottleneck for electric vehicles to penetrate the car market. Online battery models are one of the engineering tools to enhance their performance. Empirical battery models form the subject of many scientific publications. In this paper a study is performed of the usefulness of the first order impedance model through the consistency of the parameters under changes in the calibration signal, i.e. the current pulse. It can be concluded that simple first order models show little potential to really increase battery performance. Only the equivalent series resistance of the first order impedance model is insensitive to small variations of the calibration signal.

Abstract This paper represents a novel lithium-ion capacitor model. The proposed model has significantly high accuracy (less 4%). The model is an extension of Zubieta model for EDLCs. The proposed model exists of three capacitors, representing the influence of temperature, current rate (ΔC 1) and SoC (ΔC 2) on the capacitance of LiCaps, respectively. Unlike to the electrical double-layer capacitors, the model contains two resistances, illustrating the charge and discharge processes. Then, a self-discharge resistance is ...

ABSTRACT performance, cost and fuel economy. This paper presents an evaluation study of the current and future Fuel Cell Hybrid Vehicles (FCHEVs) powertrains from the point of view of the fuel economy, volume, mass and cost. In this research, different FCHEV powertrains (such as Fuel Cell/Supercapacitor (FC/SC), Fuel Cell/Battery (FC/B), and FC/SC/B) and different control strategies are designed and simulated by using Matlab/Simulink. In this paper, two standard driving cycles (NEDC and FTP75) are used to evaluate the fuel consumption. Within this study, two control strategies based on the knowledge of the fuel cell efficiency map are implemented to minimize the hydrogen consumption of the FCHEV powertrains. These control strategies are control strategy based on Efficiency Map (CSEM) and control strategy based on Particle Swarm Optimization (CSPSO). Furthermore, a comparative study of different FCHEV powertrains is provided for adequately selecting of the proper FCHEV powertrain, which could be used in industrial applications.

ABSTRACT This paper is part of a research project, which aims to investigate the possibilities of using the second life batteries after their replacement from the plug-in electric vehicles (PHEVs), hybrid electric vehicles (HEVs) and battery electric vehicles (EVs) for smart grid applications. In these applications, the power electronics converters (PECs) play a key role in the development of a high performance integrated system. This paper shows that the performance of the batteries will be affected by the performance of the PECs, which are utilized to achieve the integration of the batteries with the smart grid. Therefore, this paper demonstrates the impact of the Multi-Level DC/DC Converter (MLDC) on the performances of the battery system. The Selected Harmonic Elimination (SHE) technique is used to realize the control system of the Multi-Level DC/DC Converter (MLDC). In addition, the battery model of a Lithium-ion iron phosphate (LFP) with different capacities (7Ah, 14Ah and 20Ah) is used to investigate the impact of the switching angles and the voltage levels of each module on the performance of each battery module. This system (including the battery modules, MLDC and electric load) is designed and verified by using MATLAB/Simulink environment. Furthermore, this paper provide an extended analysis to select the proper switching angles for different units of MLDC, which can be used for both of designing the control strategy of second life battery and achieving less Total Harmonic Distortion (THD) at AC side.

ABSTRACT This paper represents the evaluation of ageing parameters in lithium iron phosphate based batteries, through investigating different current rates, working temperatures and depths of discharge. From these analyses, one can derive the impact of the working temperature on the battery performances over its lifetime. At elevated temperature (40 °C), the performances are less compared to at 25 °C. The obtained mathematical expression of the cycle life as function of the operating temperature reveals that the well-known Arrhenius law cannot be applied to derive the battery lifetime from one temperature to another. Moreover, a number of cycle life tests have been performed to illustrate the long-term capabilities of the proposed battery cells at different discharge constant current rates. The results reveal the harmful impact of high current rates on battery characteristics. On the other hand, the cycle life test at different depth of discharge levels indicates that the battery is able to perform 3221 cycles (till 80% DoD) compared to 34,957 shallow cycles (till 20% DoD). To investigate the cycle life capabilities of lithium iron phosphate based battery cells during fast charging, cycle life tests have been carried out at different constant charge current rates. The experimental analysis indicates that the cycle life of the battery degrades the more the charge current rate increases. From this analysis, one can conclude that the studied lithium iron based battery cells are not recommended to be charged at high current rates. This phenomenon affects the viability of ultra-fast charging systems.Finally, a cycle life model has been developed, which is able to predict the battery cycleability accurately.

Power electronics interfaces play an increasingly important
role in the future clean vehicle technologies. This paper
proposes a novel integrated power electronics interface (IPEI) for battery electric vehicles (BEVs) in order to optimize the performance of the powertrain. The proposed IPEI is responsible for the power-flow management for each operating mode. In this paper, an IPEI is proposed and designed to realize the integration of the dc/dc converter, on-board battery charger, and dc/ac inverter together in
the BEV powertrain with high performance. The proposed concept can improve the system efficiency and reliability, can reduce the current and voltage ripples, and can reduce the size of the passive and active components in the BEV drivetrains compared to other topologies. In addition, low electromagnetic interference and low stress in the power switching devices are expected. Theproposed topology and its control strategy are designed and analyzed by using MATLAB/Simulink. The simulation results related to this research are presented and discussed. Finally, the proposed topology is experimentally validated with results obtained from the prototypes that have been built and integrated in our laboratory based on TMS320F2808 DSP.