Battery Terminals Research Articles

Design and implementation of a 22 kW full-bridge push–pull series partial power converter for stationary battery energy storage system with battery charger

A wide variety of AC/DC power converter topologies have been developed in order to improve the system efficiency, input power factor and system redundancy for stationary battery energy storage systems. Due to the nature of high-power batteries, there is a big voltage difference between battery terminals from the end of discharge to the high charge value. To prevent unregulated battery voltages from harming the system loads, several techniques are used in the industry. A well-known old technique named as diode dropper is simple but suffers from low efficiency. Using a DC-DC converter is more advantageous, although it increases the cost. In this paper, the use of partial power processing converters which attract interest these days has been proposed as an alternative. The proposed full bridge/push-pull series connected partial power converter has a slight modification compared to the classical one presented in the literature. A system with 22 kW power rating was designed and tested. In order to compare the results, a two-switch buck-boost converter was also designed and tested for the same conditions. The results show that the proposed converter is superior to both the two-switch buck-boost converter and other topologies in terms of efficiency and response speed. Efficiencies of 97%–99% have been attained with the proposed converter.

Integrated system for power flow control between electric vehicle, utility grid and residence

This work proposes a device, external to an electric vehicle (EV), capable of adding vehicle-to-home and vehicle-to-grid functionality by using the available battery terminals in a combo connector. This configuration eliminates the need of onboard EV bidirectional inverters, reducing weight, cost and complexity while adding the possibility of integrating local renewable energy generation. In order to validate the concept of the system, design and simulations of the proposed system were carried out in a 2 kW prototype.

Internal short circuit detection in Li-ion batteries using supervised machine learning

With the proliferation of Li-ion batteries in smart phones, safety is the main concern and an on-line detection of battery faults is much wanting. Internal short circuit is a very critical issue that is often ascribed to be a cause of many accidents involving Li-ion batteries. A novel method that can detect the Internal short circuit in real time based on an advanced machine leaning approach, is proposed. Based on an equivalent electric circuit model, a set of features encompassing the physics of Li-ion cell with short circuit fault are identified and extracted from each charge-discharge cycle. The training feature set is generated with and without an external short-circuit resistance across the battery terminals. To emulate a real user scenario, internal short is induced by mechanical abuse. The testing feature set is generated from the battery charge-discharge data before and after the abuse. A random forest classifier is trained with the training feature set. The fault detection accuracy for the testing dataset is found to be more than 97%. The proposed algorithm does not interfere with the normal usage of the device, and the trained model can be implemented in any device for online fault detection.

On-Board Short-Circuit Detection of Li-ion Batteries Undergoing Fixed Charging Profile as in Smartphone Applications

In this paper, an effective and robust algorithm is developed for on-board detection of battery anomaly caused by short circuit (SC). The proposed algorithm uses the battery-terminal voltage and current information measured using battery-management system during standard uses. The proposed method is purely a noninvasive, software-based solution and does not need any additional hardware. It extracts a set of designed features from the recorded data and stores their statistics as normal operating behavior for the initial five charge–discharge cycles. After the initial characterization of the battery, the likelihood of the features of being normal are evaluated for the subsequent cycles. If a feature is likely to be healthy, then the statistics for that feature get updated with the current value. However, if the feature is not likely to be healthy, then the battery is considered to be faulty with respect to that particular feature. If more than $\text{50}\%$ of the features identify the battery as faulty, then the overall battery status is classified as faulty. A mobile application is developed to log the smartphone's battery data during charging and discharging for testing. The faulty data are generated by connecting SC resistances of various values to the battery terminals, which emulates the SC condition in the battery. The data logged in the smartphones are transferred to a PC for analysis using the proposed algorithm. $\text{100}\%$ detection accuracy is achieved for SC resistance values less than $\text{200}\,\Omega$ .

A Global Maximum Power Point Tracking Technique of Partially Shaded Photovoltaic Systems for Constant Voltage Applications

The P–V characteristics of photovoltaic (PV) array exhibit several maximum power points (MPP) during non-uniform insolation (i.e., during partial shading) conditions; there exists only one global MPP (GMPP), whereas others are referred to local MPP. This paper presents a technique to track the GMPP for the constant voltage or battery loads during partial shading conditions using a single sensor connected to the battery terminals. The proposed method introduces fast and efficient scanning based method, i.e., scanning I batt– D curve of power electronic interface at selective duty cycles to recognize the kind of the solar shading pattern (i.e., kind of P–V curve) on PV array and to find the GMPP neighborhood. Moreover, the proposed method overcomes the drawbacks of existing methods such as low convergence speed, increased number of sensors, and heavy computational complexity. The proposed GMPPT method is simulated in MATLAB/Simulink and validated through test results on a prototype for various non-uniform insolation conditions. The results have shown that this paper tracks the GMPP with best tracking efficiency and fast tracking speed. Further, the proposed method is compared with two P–V curve scanning based GMPPT methods and one global optimization based artificial bee colony method.

Development of a degradation-conscious physics-based lithium-ion battery model for use in power system planning studies

A computationally-efficient and reliable method is developed to permit the simultaneous assessment of both the short- and long-term performance of lithium-ion battery in power system planning studies. Toward this end, a physics-based equivalent circuit model of the lithium-ion battery is derived in which side reaction-induced degradation of the battery is included. Whence a computational procedure is developed to enable the parametric values of the circuit elements in the equivalent circuit model to be automatically updated as the battery operates. The resulting model allows the increase in the internal resistance and the decrease in the energy storage capacity of the battery to be determined, based solely on the information of the power flows at the battery terminals. Dynamic simulation results obtained using the developed equivalent circuit model are shown to be in close agreement with those obtained from well-established electrochemical models, but at a much reduced computational burden.

Design methodology for a dc–dc power conversion system with EIS capability for battery packs

This paper presents a design methodology for a dc-dc power conversion system (PCS) for battery packs. The methodology provides with an optimal design of the PCS and the associated inductive-capacitive filter interfacing the battery pack with the PCS. The PCS adds superior capability over conventional designs, which is performing current and voltage perturbations at the battery terminals for the so-called electrochemical impedance spectroscopy (EIS). This technique is an option for battery state-of-charge (SoC) and state-of-health (SoH) assessment. The design is optimal in the sense that it minimizes volume and system power losses. Such multi-objective optimization is addressed adopting the theory of weighted sum and Pareto front. The methodology is tested through a case study, addressing a lithium-ion battery pack. The offered analyses permit to identify the impact in system performance of diverse design variables such as dc-link voltage for the PCS and its switching frequency.

Investigations on Resistance Behavior at the Interface of Ultrasonically Welded Dissimilar Al/Cu Joints

The key focus of this research study is to analyze the weld joint resistance with microstructural evaluation of ultrasonically welded Al and Cu dissimilar wires. The typical applications of dissimilar wire bonding include automobile parts, electrical safety, and battery terminals. The weldments are further subjected to metallurgical characterization to understand the extent of molecular movements at the interface, uniformity in material diffusibility and the corresponding changes in weld joint resistance due to various ultrasonic welding energies. Ultrasonic welding trials were performed with different levels of process parameters (pressure, weld time, and amplitude) based on design of experiments. Subsequently, the welded specimens were examined through optical microscopy and the corresponding images are captured using image analyzers. Further, SEM images were investigated for understanding the surface morphology and the extent of intermetallic compounds formation and performance. The experimental results show that the increase in welding energy is inversely proportional to the degree of formation of intermetallic compounds/weld joint resistance. Besides, the surface morphology unwinds a uniform weld pattern in most of the samples while there are few voids and non-uniformity for low heat input samples.

An Ultrafast Maximum Power Point Tracking Technique for Optimal Battery Charging

In this paper, a new method is proposed for allocating and tracking the optimal charging frequency for sinusoidal chargers. The proposed method is based on tracking the maximum power point of the charging power by autovarying the frequency adaptively in order to get a unity power factor at the battery terminals. The proposed method has a superior performance in terms of convergence speed, ease of implementation, and applicability to different battery types. Details on the proposed method followed by simulation and experimental verification using different types of commercial batteries are presented.

Study of Battery Voltage Behavior Under Loading and Charging Conditions Using 3DFEM

In this paper, a lithium ion cobalt polymer battery cell is modeled using 3-D finite elements (3DFE) for the study of its performance under a wide range of operating scenarios. The electrochemistry is modeled and coupled to an electromagnetic model to forecast the cell voltage overpotential as a result of charging and discharging under six current densities. To study this phenomenon, light (C/10), medium (C/2), and high (1C) charging and discharging currents are imposed at the battery terminals and compared with experimental results. The electric field inside the electrodes and electrolyte is analyzed at each case highlighting regions where loss occurs. A magnetic field analysis depicts the total electrochemical generation of current densities inside the cell while identifying how the development of gradient currents occur, a mechanism which can shorten the life span of the battery. This paper distinguishes where 3DFE analysis battery models can be useful in studying how lithium ion batteries will behave given a particular loading or a charging profile before placing them in service.

Development of an Intelligent Charger with a Battery Diagnosis Function Using Online Impedance Spectroscopy

Battery diagnosis is vital to battery-based applications because it ensures system reliability by avoiding battery failure. This paper presents a novel intelligent battery charger with an online diagnosis function to circumvent interruptions in system operation. The charger operates in normal charging and diagnosing modes. The diagnosis function is performed with the impedance spectroscopy technique, which is achieved by injecting a sinusoidal voltage excitation signal to the battery terminals without the need for additional hardware. The impedance spectrum of the battery is calculated based on voltage excitation and current response with the aid of an embedded digital lock in amplifier in a digital signal processor. The measured impedance data are utilized in the application of the complex nonlinear least squares method to extract the battery parameters of the equivalent circuit. These parameters are then compared with the reference values to reach a diagnosis. A prototype of the proposed charger is applied to four valve-regulated lead–acid batteries to measure AC impedance. The results are discussed.

Indirect methodologies to estimate energy use in vehicles: Application to battery electric vehicles

Considering electric mobility as a viable alternative to conventional technologies, it is essential to characterize electric vehicles in terms of their real-world energy use. The objective of this work was to characterize in detail the real-world energy use of battery electric vehicles. An innovative method was developed through a calibration procedure using a group of three electric quadricycles, which were measured in real world on-road conditions for several trips by collecting 1Hz data on vehicle dynamics (speed, acceleration and slope) and energy usage (measured directly at the battery terminals). Using this dataset, and through the adaptation of the vehicle specific power approach for quadricycles, it was possible to estimate electricity consumption with an absolute error between 1.4% and 4.5%. Due to the difficulties and risks associated to direct battery measurements of voltage and current of commercially available light-duty battery electric vehicles, this methodology was expanded and validated to this vehicle class in order to define the second-by-second electricity consumption as a function of the vehicle dynamics, based only on global recharging data per trip. The results obtained for two light-duty battery electric vehicles present similar accuracy and precision when compared to experimental results obtained for the electric quadricycles, with absolute deviations between 5.2% and 7.3%. The development of indirect methodologies to estimate the real-world on-road battery electric vehicle energy use in a prompt and simple way constitutes a powerful tool to evaluate the performance of these vehicles on any real-world trip.

Study of Thermal Runaway Electrochemical Reactions in Alkaline Batteries

In this investigation, there was deduced from experiments that an exothermic reaction in the thermal runaway process in alkaline batteries is the electrochemical reaction of atomic hydrogen recombination Hads Cd + Hads Ni → H2↑(H2O + Hads + e- → H2↑ + OH- on a cathode and Hads + OH- → H2O + e- on an anode). A rate-limiting step for this reaction on both a cathode and an anode is found to be a step of metal-hydrides disintegration. This electrochemical reaction proceeds at voltage 0.5–0.6 V on battery terminals according to experimental data on the thermal runaway. The possible thermal runaway mechanism has been proposed corresponding to all the experimental results obtained.

Portable Battery Charger Berbasis Sel Surya

A type of solar battery charger is introduced in this paper. This equipment functions as a medium size rechargeable battery that is needed to move culinary merchants and coastal fishermen living in area which is not supplied by electrical networks. The equipment consists of solar module mounted onto portable mechanical construction, a 12-V 7.5-Ah lead acid battery and charge controller. Solar module charges the battery through charge controller and then the battery can be discharged to power on electric lamps for lightening culinary wagon or fisherman’s boat at night. Charge controller charges the battery with float charging which is implemented by maintaining 13.5 Volt between battery terminals and limiting the charging current to 1.5 Amperes. Charge controller circuit is based on adjustable linear voltage regulator LM338. The battery is of sealed lead acid type. This type of battery is maintenance free and more hygiene than other types of lead acid battery. The field experiment of charging the baterry of 50% residual capacity from 8 am to 4 pm under sunny weather shows that the solar module has charged the battery to its full capacity under battery safe charging conditions. Keywords: portable solar battery charger, float charging, LM338

Upon Power Loses due to Current Harmonics in a Fotovoltaic System, Opperating at Maximum Power Point

Photovoltaic panels (PF), combined with lead-acid battery (AE), are increasingly used, to produce electricity. To work in maximum power points, between (PF) and (AE) is interposed a static converter (DC-DC), which is a harmonic pollution source. Within the paper there are calculated the power losses, due to current harmonics, of a photovoltaic system working at its maximum power. Photovoltaic system works at its maximum power, if in the electronic system there is permanently voltage control among solar battery terminals.

Sudden Power Loss in a HeartMate II Left Ventricular Assist Device Due to Intermittent Pin Contact with the Battery

Left ventricular assist device technology has improved such that mechanical malfunction, particularly with newer generation continuous flow devices, is a relatively rare event. We present a case of sudden power loss in a HeartMate II caused by intermittent contact of the battery terminals after a clip was dropped with the battery inserted in it. The clip was replaced and the patient made a complete recovery. A new inspection and testing methodology, and amended approach to patient and caregiver training, designed to prevent future occurrences is described.

Bipolar transistors can detect charge in electrostatic experiments

A simple charge indicator with bipolar transistors is described that can be usedin various electrostatic experiments. Its behaviour enables us to elucidate linksbetween ‘static electricity’ and electric currents. In addition it allows us to relatethe sign of static charges to the sign of the terminals of an ordinary battery.

Исследование причин теплового разгона в герметичных никель-кадмиевых аккумуляторах

It is shown from analysis of charging current and voltage change on the terminals of sealed Ni-Cd battery at thermal runaway, that thermal runaway is accompanied by a new high-power electrochemical reaction, going at battery voltage of approximately 0.55 V.

Runtime Extension of Low-Power Wireless Sensor Nodes Using Hybrid-Storage Units

The sensor nodes of wireless sensor networks remain inactive most of the time to achieve longer runtimes. Power is mainly provided by batteries, which are either primary or secondary. Because of its internal impedance, a significant voltage drop can appear across the battery terminals at the activation time of the node, thus preventing the extraction of all the energy from the battery. Additionally, internal losses can also be significant. Consequently, the runtime is reduced. The addition of a supercapacitor in parallel with the battery, thus forming a hybrid-storage device, has been proposed under pulsed loads to increase the power capabilities and reduce both the voltage drop and the internal losses at the battery. However, this strategy has not yet thoroughly been analyzed and tested in low-power wireless sensor nodes. This paper presents a comprehensive theoretical analysis that extends previous works found in the literature and provides design guidelines for choosing the appropriate supercapacitor. The analysis is supported by extensive experimental results. Two low-capacity (< 200 mAh) batteries were tested together with their hybrid-storage unit counterparts when using an electronic load as a pulsed current sink. The hybrid-storage units always achieved a higher runtime. One of the batteries was also tested using a sensor node. The runtime extension was 16% and 33% when connecting the hybrid-storage unit directly and through a dc-dc switching regulator to the sensor node, respectively.

State of charge estimation in Ni–MH rechargeable batteries

Abstract In this work we estimate the state of charge (SOC) of Ni–MH rechargeable batteries using the Kalman filter based on a simplified electrochemical model. First, we derive the complete electrochemical model of the battery which includes diffusional processes and kinetic reactions in both Ni and MH electrodes. The full model is further reduced in a cascade of two parts, a linear time invariant dynamical sub-model followed by a static nonlinearity. Both parts are identified using the current and potential measured at the terminals of the battery with a simple 1-D minimization procedure. The inverse of the static nonlinearity together with a Kalman filter provide the SOC estimation as a linear estimation problem. Experimental results with commercial batteries are provided to illustrate the estimation procedure and to show the performance.