Search Results (194)

Inconsistencies in lithium-ion battery packs pose significant challenges for both electric vehicles and energy storage systems, causing diminished energy utilization and accelerated battery aging. This study investigates the characteristics and aging processes of 32 batteries, creating simulation models for cells and packs based on experimental data. Through a controlled single-variable approach, the decoupled analysis of multi-parameter inconsistencies is carried out. Simulation results demonstrate that parallel-connected packs can maintain charge consistency without the need for external balancing systems, thanks to their self-balancing mechanisms. On the other hand, series-connected packs experience accelerated capacity degradation primarily due to charge inconsistencies linked to differences in Coulombic efficiency (CE) and the initial state of charge (SOC). For packs with minor capacity variations and temperature inconsistencies, a passive balancing current of 0.001 C can effectively eliminate up to 3.8% of capacity loss caused by charge inconsistencies within 15 cycles. Active balancing systems outperform passive ones primarily when there is significant capacity inconsistency. However, for packs that have undergone capacity screening before assembly, both active and passive balancing systems prove to be equally effective. Additionally, inconsistencies in internal resistance have a minimal impact on overall pack capacity but limit the power of both series-connected and parallel-connected packs. These findings offer essential insights for the development of balancing systems within battery management systems. Full article

Batteries have become the main power source in today’s automotive systems. This paper proposes the design of a fast-balancing passive battery management system (BMS) with remote monitoring for the automotive domain. This system is designed for four series-connected lithium iron phosphate (LiFePO4) cells, which are the preferred choice in the automotive industry. The results show that the proposed BMS can monitor the cell voltages with an error lower than 0.12%, and it can perform the balancing operation successfully with maximum currents of 750 mA during both charging and discharging cycles, not only for LiFePO4 cells, but also for lithium-ion (Li-ion) cells. Furthermore, the cell voltages are sent over the controller area network (CAN) interface for remote monitoring. Full article

Electric vehicles have recently gained greater attention across all countries for transportation purposes in on-road and off-road forms due to their supreme performance and clean eco-friendliness status. Lithium-ferrous phosphate batteries are the primary energy storage devices in electric vehicles due to their higher energy density, longer lifespan, and lower self-discharge rate. They also possess several technical advantages, including a wider range of applications, economic affordability, an environmentally friendly nature, and, most importantly, superior electrochemical performance, which makes them a strong competitor to lead acid batteries. In the present study, a performance and health assessment of a lithium ferrous phosphate battery (LFP) pack consisting of 23 cells connected in series balancing mode with a 7360 Wh maximum energy storage capacity has been carried out at various current ranges of operation such as 3 A, 5 A, and 8 A in a typically developed battery management system to estimate their optimized performance and overall health conditions. Further study has been conducted to investigate the characteristics of LFP packs under various power-mode conditions, ranging from 20 W to 750 W. This experimental study revealed that the LFP battery pack exhibits a remarkable state-of-charge capability, achieving 58% charging in a 3.3-h runtime period. A similar decreasing trend was also observed during power-mode operations. Furthermore, the LFP battery pack was fully charged after achieving a 50% State of Charge (SOC) under every current-mode condition, providing reliable outputs under the loading conditions. It is also stated that the state of health of the lithium ferrous phosphate is significantly higher at 92% during the entire investigation, which reflects the good thermal stability of the LFP battery pack for temperature variations from 26 °C to 31 °C. Finally, it is concluded that the LFP could be one of the most favourable energy storage systems due to its longer lifespan and its great affordability in automotive applications. Full article

Triboelectric nanogenerators have attracted extensive attention as they can complete sensing during energy conversion, triggering a series of self-powered designs. Traditional TENG bipolar independent fabrication technology requires secondary motion control, which limits its application scenarios. In this work, we propose a flag-type TENG prepared using in situ electrospinning technology, in which the connecting region is obtained by electrospinning deposition of PVDF on nylon as the receiving electrode. The active area is isolated with silicone oil paper. After electrospinning, the silicone oil paper was removed, and the distance between the nylon and PVDF is far beyond the van der Waals range. Thus, contact separation can be effectively carried out under the action of wind. The device has been proven to be able to be used for monitoring wind conditions at high-speed rail stations and enables completely self-powered monitoring of the wind level using self-powered LED coding. The device no longer relies on additional batteries or wires to work, providing additional ideas for future self-powered system design. Full article

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a $2.5\mathrm{kW}$ commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of $4\mathrm{L}$ is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed. Full article

In the automotive industry, battery electric vehicles (BEVs) represent the future of individual mobility. To establish a long-term market presence, innovative vehicle and powertrain concepts are essential, and therefore, identifying the most promising concepts is crucial to determine where to focus research and development further. Academia plays a significant role in this identification process; however, researchers often face restricted access to data from the industry, and identifying different technological approaches is often connected to significant costs. We present a comprehensive study of the Porsche Taycan Performance Battery Plus, which integrates two technological advancements: the first series-production implementation of a two-speed transmission in an electric vehicle allowing for high acceleration while reaching high top speeds and a 800 V battery system architecture providing more efficient charging capabilities. This study details vehicle dynamics, electric powertrain efficiencies, their impact on vehicle level, and the two technological advancements. This work aims to provide researchers access to vehicle dynamometer and real-world data from one of the most advanced and innovative battery electric sports cars. This allows for further analysis of cutting-edge technologies that have yet to reach the mass market. In addition to providing researchers with this study’s results, all data utilized in this study will be made available as open-access, enabling individual use of test data for parameter identification and the development of simulation models. Full article

The inconsistency of individual lithium-ion batteries causes the voltage imbalance of the batteries. An effective voltage-balancing circuit is essential to improve the inconsistency of series-connected batteries. This paper presents an isolated resonant voltage-balancing circuit for series-connected lithium-ion batteries based on a multi-port transformer. This circuit utilizes the multi-port transformer to enable free energy flow among the batteries. Without any direct transmission path between the capacitor and the battery string, it achieves full isolation between them. The resonant circuit is adopted to realize the soft-switching operation. Compared with other active balancing circuits, the proposed circuit requires only half a winding and one transistor per individual battery. Consequently, the proposed circuit enhances power density and further improves efficiency and reliability. Additionally, a fixed-group-number control strategy is introduced to enhance the circuit’s equalization voltage capabilities. Finally, a prototype of the voltage-balancing circuit for 24 series-connected lithium-ion batteries is established to verify the effectiveness and feasibility of the proposed circuit. Full article

An analysis of the possibilities of using alternative energy to solve the problem of electricity shortages in developing countries shows that solar energy can potentially play an essential role in the fuel and energy complex. The geographical location, on the one hand, and the global development of solar energy technologies, on the other, create an opportunity for a fairly complete and rapid solution to problems of insufficient energy supply. An autonomous solar installation is expensive; 50% of the cost is solar modules, 45% of the cost consists of other elements (battery, inverter, charge controller), and 5% is for other materials. This work proposes the most efficient PV system, based on the technical characteristics of the SB and AB. It has a direct connection between the SB and AB and provides almost full use of the solar panel’s installed power with a variable orientation to the Sun. The development of a small solar photovoltaic (PV) installation, operating both in parallel with the grid and in autonomous mode, can improve the power supply of household consumers more efficiently and faster than the development of a large energy system. It is suggested that two minimized criteria be used to create a model for forecasting FOU. This model can be used with a genetic algorithm to make a prediction that fits a specific case, such as a time series representation based on discrete fuzzy sets of the second type. The goal is to make decisions that are more valid and useful by creating a forecast model and algorithms for analyzing small PV indicators whose current values are shown by short time series and automating the processes needed for forecasting and analysis. Full article

Realistic applications of zinc–air batteries are hindered by the high cost of Pt/C cathode catalysts, necessitating the search for alternative, sustainable electrocatalysts. In this work, we developed a sustainable Fe₃C/Fe-N_x-C cathode catalyst from waste coffee biomass for an oxygen reduction reaction (ORR) in alkaline electrolytes and zinc–air battery applications. The Fe₃C/Fe-N_x-C cathode catalyst was synthesized via a mechanochemical synthesis strategy by using melamine and an EDTA–Fe chelate complex, followed by pyrolysis at 900 °C. The obtained Fe₃C/Fe-N_x-C catalyst was evaluated for detailed ORR activity and stability. The ORR results show that Fe₃C/Fe-N_x-C displayed excellent ORR activity with an E_1/2 of 0.93 V vs. RHE, a Tafel slope of 68 mV dec⁻¹, 3.95 e⁻ transfer for the O₂ molecule, and high ECSA values. In addition, the Fe₃C/Fe-N_x-C catalyst exhibited excellent stability with a loss of 75 mV for 10,000 potential cycles, and a loss of ~14% of relative currents in the chronoamperometric test. When applied as a cathode catalyst in zinc–air battery, the Fe₃C/Fe-N_x-C catalyst delivered a power density of 81 mW cm⁻² and admirable electrochemical stability under galvanostatic discharge conditions. Furthermore, the practical application of the Fe₃C/Fe-N_x-C catalyst was demonstrated by a panel of LEDs illuminated with a dual-cell zinc–air battery connected in a series, clearly validating the practically developed catalysts for use in various energy storage and electronic devices. Full article

In this paper, a modular cell balancing circuit based on a bidirectional flyback converter (BFC) is designed, which is equipped with a symmetrical BFC for each cell. The primary side of all BFCs is in parallel with the battery pack, and the secondary side is connected to the individual cells. Such an input-parallel output-series structure allows for bidirectional and controllable energy transfer among the cells. The control of the charging/discharging for a specific cell can be realized by adjusting the PWM signal on the primary or secondary side of the corresponding BFC. Based on this, three cell balancing strategies are proposed: maximum voltage discharge (MXVD), minimum voltage charge (MNVC), and maximum and minimum voltage balancing (MX&MNB). For MX&MNB, which is essentially a combination of MXVD and MNVC, it controls the maximum voltage cell discharging and minimum voltage cell charging simultaneously, where the energy is transferred directly between the two cells with the largest voltage difference. A cell balancing prototype is built and tested to verify the feasibility and stability of the proposed strategy. All three proposed methods can implement cell balancing simply and effectively, while the MX&MNB provides a faster speed. Full article

This paper discusses the implementation of a wireless inductive power transfer system for pacemaker applications. One of the inherent challenges in these systems is regulating the output voltage, as there is no direct physical connection from the primary. Additionally, there are other challenges, such as variability in magnetic coupling. First, resonant converters for inductive charging topologies are investigated for biomedical applications. Then, a control method based on the system’s modeling is proposed, eliminating the need for communication. This method is designed for systems with variable and unknown coupling and specifically for a resonant series–parallel topology. For an operation point, determined by the coupling factor, the primary current is measured to regulate the output voltage by adjusting the input voltage. The relationship between the input current and the input voltage is set by a look-up table. The effectiveness of this control strategy is validated in the PSIM simulator and with experimental results for a coupling range between 0.3 and 0.5, achieving a regulated output current error of less than 1%, and an output voltage range within the limits of the battery charger. Full article

Accurate estimation of the state of energy (SOE) in lithium-ion batteries is crucial for determining the output power and driving range of electric vehicles. However, in series-connected battery packs, inconsistencies among individual cells pose significant challenges for precise SOE estimation. This issue is particularly pronounced for lithium iron phosphate (LFP) batteries. Their relatively flat open-circuit voltage (OCV) curve makes the classic method of directly weighting the SOE of representative cells—commonly used for ternary batteries—ineffective. This is because the traditional method relies heavily on a linear relationship between the SOE and the voltage, which is not present in LFP batteries. To address this challenge, a novel SOE estimation approach based on the online construction of the battery pack’s comprehensive OCV curve is proposed in this paper. In this new approach, the weighting of representative cells shifts from a result-oriented mode to a key-parameter-oriented mode. By adopting this mode, the whole pack’s comprehensive OCV can be obtained training free and the pack’s SOE can be estimated online within an equivalent circuit model framework. The experimental results demonstrate that the proposed method effectively controls the SOE estimation error within 3% for series battery packs composed of cells with varying degrees of aging. Full article

Battery modules in eco-friendly mobility are composed of series and parallel connections of multiple lithium-ion battery cells. As the number of lithium-ion cells in the battery module increases, the cell connection configuration becomes a critical factor affecting the module’s usable capacity efficiency. Therefore, careful consideration of this factor is essential in battery module design. Various design elements have been studied to optimize the performance of battery modules. Among these elements, the method of terminal connection affects the distribution of resistance components in each cell, causing DOD (Depth of Discharge) variation. Previous research has focused on determining the optimal terminal placement and cell connection method to minimize DOD variation between cells. However, these studies did not consider temperature effects. Since temperature acts as a major variable affecting the DOD of each cell, comprehensive research that includes this factor is necessary. This research performed 3D thermal flow analysis using Ansys Fluent 2024 R2 and validated the simulation environment by comparing actual experimental and simulation results for a single cell. Based on the validated simulation environment, this research analyzed the impact of temperature distribution on cell performance in a 4S3P module and proposed a method of terminal connection, which achieved a 70% reduction in SOC deviation compared to conventional methods. Additionally, this research suggests that when the module configuration changes, a new design approach specific to that configuration is necessary to minimize SOC deviation. Full article

This study experimentally assesses the thermal performance of a proposed phase change material (PCM)-based battery pack under elevated ambient temperatures. In addition, the novel approach of the research addresses scenarios where the ambient temperature reaches the PCM’s melting point while maintaining the initial temperature at the ideal operating point of 22 °C. The experiments employed nine 2500 mAh 18650 lithium-ion cells connected in series and subjected to constant-current discharges of 1C and 3C, with a conventional air-cooled system as the baseline and paraffin as the PCM. The results indicate that as the ambient temperature reached the PCM’s melting point, approximately 98% utilization of the PCM around the heating cell was achieved. Additionally, the PCM demonstrates noticeable advantages over the baseline by stabilizing the temperature profile and reducing the maximum temperature increase rate from over 18 °C in the baseline system to around 7 °C. Notably, under a high-load (3C) discharge rate, the PCM-based system successfully maintained battery temperatures below 42 °C, demonstrating its effectiveness under demanding operational scenarios. These findings establish a critical baseline for PCM-based BTMSs operating under elevated ambient temperatures and up to the melting point of the PCM, thereby informing future research and development of more efficient PCM-based thermal management solutions. Full article

This paper proposes an isolated bidirectional dc-dc converter (IBDC) without a cooling fan with a low profile for a direct connection between a battery and the IBDC. To implement the low-profile IBDC, a dual active bridge (DAB) and two interleaved buck/boost converters are adopted in the proposed system. For the IBDC with a low profile and high efficiency, two transformers in the DAB converter are separated in series on their primary side and in parallel on their secondary side. In addition, in two interleaved buck/boost converters, their inputs and outputs are connected in parallel, and interleaving control is applied for a small total of inductor current ripple. Finally, a double heat sink is designed for excellent heat dissipation performance. A 500 W low-profile and fanless prototype with 650 V input and 1 (60 W)~5 V (500 W) output was made to verify its performance of operation, efficiency, and saturation temperature. Full article