Current-voltage Method Research Articles

Multi-objective optimization for multi-stage constant current charging for Li-ion batteries

Fast charging is a key challenge for the widespread adoption of electric vehicles (EVs), as it can make EVs more convenient and appealing to consumers. Therefore, different charging methods are proposed to enhance the performance of lithium-ion batteries (LIBs). Multi-stage constant current (MSCC) charging can improve LIB's performance in several aspects, including charging time, charged capacity, temperature rise, average temperature rise, and charging energy efficiency. However, achieving a multi-objective performance during LIB charging is challenging. In this paper, the Taguchi method is used to determine the multi-objective optimal (MOO) charging profile for the MSCC charging strategy. The Orthogonal experiments are designed and conducted to find the optimal solutions for each performance parameter for a five-stage constant current (5SCC) charging profile. A comparison is conducted among the performance-based selective charging profiles to validate the optimal charging profile. Furthermore, a comparison is made between the obtained MOO charging profile and the classical equivalent constant current constant voltage (CCCV) method. Experimental results demonstrated that the MOO charging profile reduces the charging time with comparable temperature rise to the CCCV, making it promising for the future alternative efficient EV charging. These findings highlight the effectiveness of the MSCC approach in improving LIB performance.

Comparison of Active Full Compensation Control Algorithms for Single-phase Grounding Residual Current in Distribution Networks

Current method and voltage method are two full compensation arc suppression control algorithms commonly used for single-phase grounding faults in the distribution network. The current method has a good compensation effect under small transition resistance, while the voltage method has a good compensation effect under large transition resistance. The existing research focuses on the control principle and implementation method of the current method and voltage method, but there is less research on the applicable boundary and comparative analysis of the control effect of these two methods. In view of this, this paper deduces the residual current full compensation theory of distribution network single-phase ground fault, introduces the control principles and implementation methods of the current method and voltage method respectively, establishes two evaluation indexes of residual current compensation accuracy and residual current compensation time, and conducts simulation and comparative research on the control effects of the two methods under different transition resistance and fault location. The results show that the dividing range of transition resistance applicable to the two methods is about 250 Ω–500 Ω. Within the dividing range, the compensation effect and control time of the two methods are equivalent. The current method surpasses the voltage method in compensation effect and control time below the dividing range, while the voltage method is superior to the current method in compensation effect and control time above the dividing range.

Sensitive and Selective Detection of Chloroform by Current-Voltage Using ZnO Nanorods Modified Electrode

The development of in situ chloroform detection is crucial due to the high risk of carcinogenic effects associated with chloroform exposure. In this study, an electrochemical-based chloroform sensor was fabricated using undoped ZnO nanorods on indium tin oxide (ZnONRs/ITO) electrode to detect chloroform in aqueous-phase samples. Based on the results, the FESEM imaging showed that the ZnONRs exhibited an evenly distributed circular structure with a diameter of 62-90 nm, while the EDX and XRD findings confirmed the presence of Zn and O elements deposited on the electrode surface. Furthermore, the phosphate buffer solution (PBS) solution significantly affected the performance of the modified electrode with an optimal concentration and pH of 0.1 M and pH 7. The results also highlighted the vital function of the modified ZnONRs/ITO electrode as an efficient electron mediator and its catalytic potential to induce chloroform oxidation. Most importantly, the modified ZnONRs/ITO electrode was able to detect the presence of chloroform in real seawater samples, where the repeatability and reproducibility tests achieved a Relative Standard Deviation (RSD) of 1.41% and 2.61%, respectively, indicating the exceptional performance of the modified electrode. Moreover, the modified ZnONRs/ITO electrode recorded a low limit of detection and high sensitivity of 1.50 µM and 2.11 µA/cm2·mM, respectively, within a 0.010-10 mM linear dynamic range. In conclusion, the current-voltage (I-V) method proved the reliable, satisfactory, and effective fabrication of the modified ZnONRs/ITO electrode for chloroform sensing in aqueous-phase samples, including in real seawater samples.

Dynamic Direct Voltage MTPA Current Sensorless Drives for Interior PMSM-Based Electric Vehicles

This research presents a current sensorless dynamic direct voltage method based on the maximum torque per ampere (MTPA) technique to control the rotor speed of interior permanent magnet synchronous motors (IPMSMs) for electric vehicle (EV) applications. It considers the dynamic model of the machine and generates a particular pair of voltage amplitude and its angle to track the speed profile of the driving cycle. The proposed control strategy contributes by eliminating the need for a current sensor, avoiding cascaded PI controllers, and overcoming the limitations of transient states. Consequently, the measurement noise and equipment failure do not affect the control loop, the tuning of a single PI controller becomes much simpler than two cascaded PI controllers, and the absence of MTPA tracking and current or voltage overshooting at transient states cannot limit the performance of the control technique. Additionally, the aforementioned modifications improve the response time of the proposed strategy and make it nimble enough for EV applications. A comparative analysis is carried out on the proposed current sensorless dynamic direct voltage MTPA control, simplified dynamic direct voltage control (S-DDVC), and the field oriented control (FOC) models. The outcomes confirm that the introduced model substantially reduces the inrush current and voltage. Experimental results with quantitative tracking and energy consumption assessments reveal that the proposed method demands 9.7% lower energy than the FOC counterpart in urban driving plans by operating IPMSM in high efficiency region.

Experimental Study of Multistage Constant Current Charging with Temperature Awareness Control Method

Temperature and charging time are critical parameters during charging period of a battery as temperature rise affects battery life. In a particular charging method, setting high current minimizes charging time but raises temperature. In this study attention is given to multistage constant current charging approach to shorten charging time while maintaining battery temperature below preset range. Battery charging characteristics of various methods are studied, and their performance is compared. The proposed multistage charging method is compared with constant current constant voltage and traditional multistage charging method. The experimental results obtained show that, the proposed method reduces the charging time by 42.22 % and 9.3 % as compared to the constant current constant voltage and conventional multistage charging method respectively, while limiting the rise in battery's temperature to 5°C above room temperature. Further in the proposed method, battery temperature is reduced by 20% as compared to the conventional multistage method.

Constant current-fuzzy logic algorithm for lithium-ion battery charging

<p>The lithium-ion (Li-ion) battery has a high demand because of its long cycle, reliability, high energy density, low toxic, low self-discharge rate, high power density, and high efficiency. However, lithium-ion batteries have sensitivity to over-charge, temperature, and charge discharge currents. The conventional battery charging system takes a very long time to charge which makes the battery temperature high. Therefore, a charger system that can maximize charging capacity, shorten charging time, and extend battery life is needed. In this study, a battery charging system was developed using the constant current–fuzzy (CC-fuzzy) control method. The aim is to get faster charging time and maintain battery life by limiting the battery charging temperature. The proposed charger system is dual mode which can be operated in both buck and boost mode. The experimental result shows that the proposed method is superior compared to the constant current constant voltage (CCCV) method in charging time. The CC-fuzzy method charging time is faster compared to the CCCV method by 25% and 12.5% in buck and boost modes, respectively. Whereas from the battery temperature, in buck mode, the proposed method has a lower temperature by 0.5 ⁰C and in the boost mode, each method has the same temperature.</p>

Design and Control of an Off Board Battery Charger for Electric Vehicles

The rise in the penetration of electric vehicles has led to the increased interest in the charging technologies. Controlled charging and vehicle to grid power transfer is being given much importance. This paper proposes an off board charger (three phase) for charging the batteries used in electric vehicles. The proposed charger has a bidirectional power transfer capability so as to transfer power back to the utility grid. The topology proposed is simple and less costly as it has fewer elements. The charger has two converters, a three phase ac-dc converter for conversion of ac into dc and bidirectional dc-dc converter. The technique called Vector control is used to control ac-dc converter which allows controlling of active and reactive power independently. The control strategy proposed here provides a better control and leads to a better performance while maintaining unity power factor at input. The charging algorithm designed is such that it is able to maintain voltage at dc link at desired value. The charging algorithm is designed for lithium ion batteries and the combined Constant Current Constant Voltage (CC-CV) method of charging is used because it is simple and easy to implement. The proposed electric vehicle charger changes the mode of charging with change in State of Charge (SOC). The different modes are switched and the suitable reference is generated based on the different charging characteristics of a battery. The proposed charger is modeled in MATLAB-Simulink. The working operation of both forward and reverse power transfer mode has been analyzed. The proposed charger is able to maintain the unity power factor operation. The simulation results of all modes validate the design and control of the proposed charging topology.

A lithium ion selective membrane synthesized from a double layered Zrbased metalorganic framework (MOF-on-MOF) thin film

The ever-growing global demands for lithium (Li+) require energy-efficient techniques to separate lithium from natural resources and commercial wastewaters. We propose a facile seed-assisted in-situ growth method to prepare double-layered UiO-66-based (–(COOH)2 and –NH2) membranes for Mg2+ and Li+ separation in brine. These membranes, with sub-nanometer-sized windows, nanometer-sized cavities, and functional groups can selectively transport K+, Na+, Li+ over Mg2+ and Ca2+. A carboxyl-functionalized UiO-66-based membrane showed higher Li+ and Mg2+ selectivity (up to 90.8) than a UiO-66-NH2 membrane (65.0) by the current-voltage method using single salt solutions. Carboxylic groups greatly enhance membrane selectivity for Li+ over Mg2+. The effects and mechanisms of (i) different feed concentrations in a mono-ion system, and (ii) concentration gradients and electrical potential as driving forces for Li+ extraction in a synthetic multi-ion brine, are discussed. The UiO-66-(COOH)2/UiO-66-NH2 anodized aluminum oxide membrane exhibited excellent Mg2+/Li+ separation efficiency in synthetic Qinghai Taijiner salt lake brine (abbreviated as Taijiner brine) under concentration gradients. This research will promote metal-organic framework-based membrane designs with tailored pore morphologies and provide an innovative and eco-friendly solution for Li+ enrichment from salt lake brines.

Constrained Bayesian Optimization for Minimum-Time Charging of Lithium-Ion Batteries

The fast charging of lithium-ion batteries while minimizing battery degradation is a key challenge to battery community. Difficulties in this optimization are the high dimensionality of parameter space of charging strategies, significant variability between batteries (even from the same production line), and limited quantitative information on battery degradation mechanisms. Current approaches to addressing these challenges are model-based optimization and grid search. Model-based methods are limited by the insufficient complexity and accuracy of electrochemical models – especially in the early stage of development when a new battery chemistry is being introduced to the market – and grid search methods are expensive in terms of testing time and cells. This article proposes a data-driven Bayesian optimization (BO) approach for minimum charging time problem, in which an acquisition function of constrained expected improvement is employed to explicitly handle constraints that limit degradation. In addition, continuous-varied-current charging protocols are introduced into the proposed BO approach by utilizing the technique of polynomial function expansions. The effectiveness of the proposed approach is demonstrated on the LIONSIMBA, a porous electrode theory-based battery simulator. The simulation results show that the proposed BO-based charging approach with continuous current profile outperforms the commonly used constant current constant voltage (CC-CV) method for the minimum charging time problem. Moreover, the decrease in the minimum charging time and increase in its variance with increasing number of degrees of freedom used in charging protocols is also quantified.

An Accurate Battery Charger SEPIC-Coupled Inductor Using Fuzzy Type 2

Recently, the needs of electrical energy have increased in line with the increasing population in Indonesia. Electrical in order to save the use of fossil energy, renewable is used, namely solar energy. Solar energy depends on the conditions of sunlight and the temperature of the solar panel. So, if the solar panel is directly connected to the battery, it will cause the battery be damaged. To overcome this, a controlled DC-DC converter is needed to stabilize the solar panel output before connecting to the battery. The DC-DC converter that used is a SEPIC coupled inductor converter, this converter has the ability to increase efficiency, the output polarity is not reversed, and avoid input current ripple. The control used to adjust the output of the SEPIC converter is a type 2 fuzzy logic controller because it has ability to find a set point value faster than other control logics and can handle uncertainty better than a type 1 fuzzy logic controller. The output of the SEPIC converter is used for charging lithium ion battery with a capacity 12V 21Ah. The output value of the SEPIC converter is 12.6V for charging voltage and 7A for charging current. The method used for battery charging is the constant current constant voltage method (cc-cv).

Recovery Behavior of Interface Traps After Negative Bias Temperature Instability Stress in p-FinFETs Featuring Fast Trap Characterization Technique

We present an experimental study on the recovery feature of generated interface traps (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IT</sub> ) after the application of dc/ac negative-bias temperature instability (NBTI) stress in Si p-FinFETs using a fast direct-current current-voltage method. In addition to the delayed recovery that typically occurs after a 10-ms recovery time, the immediate recovery of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> IT</sub> starting within a recovery time of 400 μs is observed, which is missing in the current reaction-diffusion model. In this study, this immediate recovery is systematically investigated under different stress modes and is attributed to the accumulation of H atoms. Furthermore, when the accumulated H atoms in a pulse-on phase are quickly consumed in the following pulse-off phase, a widely reported delayed recovery after Mode-B ac stress is observed.

Investigate Thermodynamic and Kinetic Degradation of Lithium-Ion Batteries through a Combined Experimental and Modeling Approach

With the significant cost reduction of Li-ion battery (LIB) (85% in the past 10 years), 50-fold growth in market penetration of the technology has been projected through to 2030 for modern transportation and renewable energy integration [1]. LIB is a high energy density, high round-trip efficiency, high reliability energy storage device [2]. Different from Internal Combustion Engine, as a power generator, LIB pack is sealed in a certain container and its status need to be estimated by additional diagnostic instruments with specific electrochemical performance data. The traditional methods to estimate State of Charge (SOC) and State of Health (SOH) include current integration method and open circuit voltage method, which are time-consuming (over 1 day) and rely on historical information of the system [3]. Impedance spectroscopy technique can capture both thermodynamic and kinetic information of the LIB in a relatively short time, however, it is difficult and sometimes unreliable to interpret the data by using a simplified equivalent circuit method (ECM). In our recent publication [4], we also find that nonideality effect caused by interaction among high concentration Li ions could lead to nonlinear transport and kinetic parameters as a function of SOC. In this research work, we would like to use the perturbation form of a physics-based LIB model considering the nonideality feature of the cell to deconvolute the electrochemical impedance spectroscopy (shown in Fig.1) of a LIB coin cell operating under different SOCs and different number of cycles. After proper status evaluation of beginning of life (BOL) of the cell, parasitic side reactions, the solid electrolyte interface (SEI) formation in anode and cathode, are included as the indicators of degradation. A nonlinear optimization procedure will be used to identify the parameters associated with the cell capacity loss in each electrode, solid/liquid interface reaction, Li-ion diffusion, ohmic resistance, etc. The results will map out the cell capacity loss caused by thermodynamic degradation and deteriorated reaction kinetics and diffusivity caused by the growth of the SEI layers during cycling. It will provide important guidance in designing fast and accurate LIB real-time diagnostic devices.

Applications of Direct-Current Current–Voltage Method to Total Ionizing Dose Radiation Characterization in SOI NMOSFETs with Different Process Conditions

As a promising candidate in space radiation hardened applications, silicon-on-insulator (SOI) devices face the severe problem of total ionizing dose (TID) radiation because of the thick buried oxide (BOX) layer. The direct-current current–voltage (DCIV) method was applied for studying TID radiation of SOI metal–oxide–semiconductor field–effect transistors (MOSFETs) with different manufacture processes. It is found that the peak of high-voltage well (PX) devices shows a larger left-shift and a slower multitude increase along with radiation dose, compared with that of low-voltage well (PV) devices. It is illustrated that the high P-type impurity concentration near back interface makes it more difficult to break up silicon hydrogen bonds, which gives the PX devices superiority in resisting the build-up of interface traps. The study results indicate that increasing doping concentration of the body region near the back-gate interface might be an alternative radiation hardening technique of SOI MOSFET devices to avoid the parasitic back transistors’ leakage.

Electrical Characterization of 6H-SiC/MEH-PPV/Al Schottky Diode by Current-Voltage Method in A Wide Temperature Range

Schottky diode with 6H-SiC/MEH-PPV/Al polymer interface was prepared and characterized by using current-voltage data in the temperature range of 80-400K. Important parameters of the produced diode such as ideality factor, barrier height and saturation current were calculated. In addition, the series resistance of the diode was calculated using Cheung and Norde methods. In addition, the calculated diode characteristics were discussed by comparing with each other and with the literature. Strong dependence of the calculated characteristics on temperature has been determined.

State of Charge Evaluation of Power Battery Pack Through Multi-Parameter Optimization

Abstract The state of charge (SoC) is an important index of the energy output performance of power battery pack. But the SoC value is affected by various factors, namely, ambient temperature, working current, equilibrium potential, and the consistency between batteries in the pack. These factors might dampen the accuracy of the traditional SoC evaluation methods like current–voltage method and Kalman filter. The evaluation accuracy is also influenced by the data drift and rest time to equilibrium potential. Considering the multiple influencing factors of SoC, this paper analyzes the data drift and rest time to equilibrium potential, and builds an approximate model of overpotential for 32650 LiFePO4 battery, based on the time variation constant and the monotonicity of SoC trend. The proposed model was adopted to optimize the evaluation of SoC. To verify its effectiveness, the proposed method was compared with current–voltage method and Kalman filter through experiments. The results show that our method outperformed the contrastive methods in simplicity, relative error (&amp;lt;2.33%), compatibility, and state of health (SoH).

Researchers create nondestructive technique to study atomic switching

The current-voltage measurement method for tunneling analysis was used to show that moisture supports the electrochemical mechanics of atomic switching.

The effect of S/Se ratio on the properties of Cu2CdGe(SxSe1−x)4 microcrystalline powders for photovoltaic applications

The morphology, structural and compositional properties of Cu2CdGe(SxSe1−x)4 (x = 0; 0.05; 0.1; 0.15; 0.2; 0.4; 0.6; 0.8; 1) microcrystalline powders and solar cells based on these powders are investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy as well as current-voltage and external quantum efficiency (EQE) methods. XRD analysis showed that all Cu2CdGe(SxSe1−x)4 solid solutions synthesized at 700 °C crystallize in orthorhombic structure (Pmn21) regardless of S/Se ratio. Cu2CdGe(SxSe1−x)4 solid solutions (x = 0; 0.05; 0.1) synthesized at 500 °C have a tetragonal structure (I-42m). Cu2CdGe(SxSe1−x)4 solid solution with x = 0.15 has a mixture of two crystal structures. Lattice parameters decrease by increasing the S-content in the solid solutions. The median crystal size decreased with the increasing S content in the Cu2CdGe(SxSe1−x)4 powders about two times.According to EQE measurements of the solar cells, the band gap of the Cu2CdGe(SxSe1−x)4 absorber material shifted towards shorter wavelengths with increasing S content, growing from 1.27 eV for x = 0 to 2.04 eV for x = 1. In this study, Cu2CdGe(SxSe1−x)4 solid solution with x = 0.2 enabled the highest power conversion efficiency of 6.4% for monograin layer solar cells with parameters VOC = 724 mV, JSC = 18.8 mA/cm2 and FF = 46.9%.

Non-enzymatic simultaneous detection of acetylcholine and ascorbic acid using ZnO·CuO nanoleaves: Real sample analysis

A facile wet-chemical technique used to prepare the zinc oxide doped copper oxide nanoleaves (ZnO·CuO nanoleaves) in alkaline phase. ZnO·CuO nanoleaves were examined using a variety of conventional techniques for example UV–Visible, FTIR, XRD, FESEM equipped XEDS, and XPS. A non-enzymatic sensor was prepared with modification of a slightly deposited of ZnO·CuO nanoleaves onto a flat GCE, which fabricated through a conducting nafion polymer matrix in order to detect selective acetylcholine and ascorbic acid simultaneously. Analytical performances such as sensitivity, LOD, LOQ, LDR, and durability of the selective acetylcholine and ascorbic acid sensors were examined through a conventional current–voltage method. Calibration graphs of acetylcholine and ascorbic acid sensors were found linear (R2 = 0.9049 and 0.9201) over a good concentration range (100.0 pM–100.0 mM) respectively. Sensitivity (317.0 and 94.94 pAμM-1cm−2), LOD (14.7 and 12.0 pM), and LOQ (490.0 and 367.0 mM) of acetylcholine and ascorbic acid sensors were calculated correspondingly from the slope of the linear portion of calibration graph. Preparation of ZnO·CuO nanoleaves using wet-chemical technique is an excellent approach for the advancement of nanomaterial based on sensor development in support of enzyme free detection of biological molecules for the safety in healthcare and biomedical fields. This expected sensor applied for the specific determination of acetylcholine and ascorbic acid in real samples (Human, mouse, and rabbit serum, orange juice, and urine) and found satisfactory and acceptable results.

Methods for Accurate Resistance Measurement

Many devices have components that have very low ohmic properties. The resistances of these components should be measured to ensure their value doesn’t change. An overview is presented on precision resistance measurement for values less than 100Ω. Few techniques like Wheatstone bridge, current-voltage method, current comparators are discussed here.

Discharge and Optical Emission Spectrum Characteristics of a Coaxial Dielectric Barrier Discharge Plasma-Assisted Combustion Actuator

A coaxial dielectric barrier discharge plasma-assisted combustion actuator (DBD-PACA) system was set up to study its discharge and optical emission spectrum (OES) characteristics in space in this paper. Results showed that each discharge cycle can be divided into four stages: a, b, c, and d. Discharge-on only occurred in stages b and d. Comparatively, the discharge intensity was larger in stage d due to the memory effect of excited electrons. Moreover, Lissajous figure and current-voltage methods were utilized to calculate the power of the coaxial DBD-PACA, and both methods produced roughly similar results. The power presented an upward trend with increasing input voltage and airflow rate. In addition, numerous second positive system (SPS) excited nitrogen molecules were detected from the OES signals. The intensity of the spectral lines (297.54 nm, 315.76 nm, 336.96 nm, and 357.56 nm) first increased, then maintained, and then increased rapidly with the increased radius; however, the intensity of the spectral lines (380.34 nm, 405.80 nm, and 434.30 nm) basically remained unchanged, then increased, and finally decreased with the increased radius. The vibrational temperature first decreased quickly and then increased and reached the minimum at r = 18 mm with the increased radius. The vibrational temperatures at all collection points decreased with the increased input voltage. However, within the range of 0–280 L/min, when r was lower than 15 mm, the vibrational temperatures first increased rapidly and then decreased slowly; when r was greater than 15 mm, the vibrational temperatures first increased and then basically remained stable.