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1
Galvão, José Rodolfo, Lucas Braggião Calligaris, Kawe Monteiro de Souza, Joelton Deonei Gotz, Paulo Broniera Junior, and Fernanda Cristina Corrêa. "Hybrid Equalization Topology for Battery Management Systems Applied to an Electric Vehicle Model." Batteries 8, no. 10 (October 12, 2022): 178. http://dx.doi.org/10.3390/batteries8100178.
Повний текст джерелаАнотація:
This paper presents a hybrid equalization (EQ) topology of lithium-ion batteries (LIB). Currently, LIBs are widely used for electric mobility due to their characteristics of high energy density and multiple recharge cycles. In an electric vehicle (EV), these batteries are connected in series and/or parallel until the engine reaches the voltage and energy capacity required. For LIBs to operate safely, a battery management system (BMS) is required. This system monitors and controls voltage, current, and temperature parameters. Among the various functions of a BMS, voltage equalization is of paramount importance for the safety and useful life of LIBs. There are two main voltage equalization techniques: passive and active. Passive equalization dissipates energy, and active equalization transfers energy between the LIBs. The passive has the advantage of being simple to implement; however, it has a longer equalization time and energy loss. Active is complex to implement but has fast equalization time and lower energy loss. This paper proposes the combination of these two techniques to implement simultaneously to control a pack of LIBs, equalizing voltage between stacks and at the cell level. For this purpose, a pack of LIBs was simulated with sixty-four cells connected in series and divided into eight stacks with eight battery cells each. The rated voltage of each cell is 3.7 V, with a capacity of 106 Ah. The total pack has a voltage of 236.8 V and 25 kW. Some LIBs were fitted with different SOC values to simulate an imbalance between cells. In the simulations, different topologies were evaluated: passive and active topology at the cell level and combined active and passive equalization at the pack level. Results are compared as a response time and state of charge (SOC) level. In addition, equalization topologies are applied in an EV model with the FTP75 conduction cycle. In this way, it is possible to evaluate the autonomy of each equalization technique simulated in this work. The hybrid topology active at the stack level and passive at the module level showed promising results in equalization time and autonomy compared with a purely active or passive equalization technique. This combination is a solution to achieve low EQ time and satisfactory SOC when compared to a strictly active or passive EQ.
2
Luo, Shengyi, Dongchen Qin, Hongxia Wu, Tingting Wang, and Jiangyi Chen. "Multi-Cell-to-Multi-Cell Battery Equalization in Series Battery Packs Based on Variable Duty Cycle." Energies 15, no. 9 (April 29, 2022): 3263. http://dx.doi.org/10.3390/en15093263.
Повний текст джерелаАнотація:
Batteries are widely used in our lives, but the inevitable inconsistencies in series-connected battery packs will seriously impact their energy utilization, cycle life and even jeopardize their safety in use. This paper proposes a balancing topology structure combining Buck-Boost circuit and switch array to reduce this inconsistency. This structure can realize multi-cell-to-multi-cell (MC2MC) battery balancing by controlling the switch array and having a fast balancing speed, easy expansion and few magnetic components. Then, the operation principle of the proposed balancing topology is analyzed, and the simulation model is verified. In addition, the effects of switching frequency and voltage difference on the equalization effect are further analyzed. The results show that the higher the switching frequency, the lower the time efficiency, but the higher the energy efficiency. The voltage difference significantly impacts the duty cycle, so it is absolutely necessary to introduce a variable duty cycle in the multi-cell-to-multi-cell equalization. Finally, eight series batteries are selected for simulation verification. The simulation results show that, compared with any-cell-to-any-cell (AC2AC) equalization, the time efficiency of multi-cell-to-multi-cell equalization is improved considerably, the energy efficiency is improved slightly, and the variance of the completed equalization is reduced, demonstrating the excellent performance of multi-cell-to-multi-cell equalization.
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Xu, Peng, Longyun Kang, Di Xie, Xuan Luo, and Hongye Lin. "A Switch-Reduced Multicell-to-Multicell Battery Equalizer Based on Full-Bridge Bipolar-Resonant LC Converter." Batteries 8, no. 6 (June 3, 2022): 53. http://dx.doi.org/10.3390/batteries8060053.
Повний текст джерелаАнотація:
Many battery equalizers have been proposed to achieve voltage consistency between series connected battery cells. Among them, the multicell-to-multicell (MC2MC) equalizers, which can directly transfer energy from consecutive more-charged cells to less-charged cells, can enable fast balancing and a high efficiency. However, due to the limitations of the equalizers, it is not possible to achieve fast equalization and reduce the size of the circuit at the same time. Therefore, a MC2MC equalizer based on a full-bridge bipolar-resonant LC Converter (FBBRLCC) is proposed in this paper, which not only implements MC2MC equalization, but also greatly reduces the circuit size by reducing the number of switches by nearly half. A mathematical model and simulation comparison with conventional equalizers are used to illustrate the high-speed equalization performance of the proposed equalizer and excellent balancing efficiency. An experimental prototype for eight cells is built to verify the performance of the proposed FBBRLCC equalizer and the balancing efficiencies in different operating modes are from 85.19% to 88.77% with the average power from 1.888 W to 14.227 W.
4
Bacchi, C., A. Dawiec, and F. Orsini. "Pragmatic method for fast programming of hybrid photon counting detectors." Journal of Instrumentation 17, no. 01 (January 1, 2022): C01026. http://dx.doi.org/10.1088/1748-0221/17/01/c01026.
Повний текст джерелаАнотація:
Abstract It is now been over 15 years since Hybrid Photon Counting Detectors (HPCD) became one of the standard position-sensitive detectors for synchrotron light sources and X-ray detection applications. This is mainly due to their single-photon sensitivity over a high dynamic energy range and electronic noise suppression thanks to energy thresholding. To reach those performances, all HPCD pixels must feature the same electrical response against photons of the same energy. From the analysis of a monochromatic beam, in case of an ideal HPCD detector, it would be sufficient to apply a fixed voltage threshold among all pixels, positioned at half of the mean pulse amplitude to count every photon above the threshold. However, in practical cases, it must be considered that noise baselines from all pixels are not always strictly located at the same voltage level but can be spread over some voltage ranges. To address this kind of issue, most of all HPCDs apply a conventional threshold equalization method, that mainly relies on three steps; the setting of a global threshold at an arbitrary value, the identification of pixels noise baseline around that global threshold through an in-pixel threshold trimmer, and the computation of the required threshold offsets for setting all pixels at their own noise baseline at the same time. However, in case of a first-time use of an HPCD prototype, the threshold equalization might be biased by parameters that are wrongly set. Those biases can sometimes be characterized by the inability to localize some pixel noise baselines, which could be outside the voltage range of the threshold trimmer. The recovery of those biased pixels could be performed by changing the position of the global threshold, or by increasing the voltage range of the threshold trimmer. Unfortunately, both solutions could be time consuming due to the lack of information on the required steps for recovering all noise baselines. In order to overcome this issue in a reasonable time, this work introduces a pragmatic method that can be applied to HPCDs for an early and effective identification of appropriate pixels’ parameters, avoiding the need to test a high number of pixels configurations. The application of this method, at the early stage of the HPCD calibration, may drastically reduce the investigation time for finding the optimal operating parameters of HPCD prototypes.
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Roth, Thomas, Luiza Streck, Nedim Mujanovic, Martin Winter, Philip Niehoff, and Andreas Jossen. "Transient Self-Discharge after Formation in Lithium-Ion Cells: Impact of State-of-Charge and Anode Overhang." Journal of The Electrochemical Society 170, no. 8 (August 1, 2023): 080524. http://dx.doi.org/10.1149/1945-7111/acf164.
Повний текст джерелаАнотація:
A fast determination of cell quality after formation is challenging due to transient effects in the self-discharge measurement. This work investigated the self-discharge of NMC622/graphite single-layer pouch cells with varying anode dimensions to differentiate between SEI growth and anode overhang equalization processes. The transient self-discharge was measured directly after formation via voltage decay and for 20 weeks of calendar storage at three states-of-charge (SOC), 10%, 30%, and 50%. The transient behavior persisted for the entire measurement duration, even at a low SOC. Still, the low SOC minimized the impact of SEI growth and anode overhang equalization compared to moderate SOCs. Evaluating the coulombic efficiency from cycle aging showed a distinct capacity loss for the first cycle after storage, indicating further SEI growth, which stabilized in subsequent cycles. The aged capacity after cycling showed no significant dependence on the calendar storage, which further promotes fast self-discharge characterization at low SOC.
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Jing, Kai, Ningmei Yu, Xing Quan, Zhaonian Yang, and Zhongjie Guo. "Dynamic equalization and fast settling based wide operating voltage range 93 dB PSRR PTAT current reference." Microelectronics Journal 101 (July 2020): 104812. http://dx.doi.org/10.1016/j.mejo.2020.104812.
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Gallardo-Lozano, Javier, Abdul Lateef, Enrique Romero-Cadaval, and M. Isabel Milanés-Montero. "Active Battery Balancing for Battery Packs." Electrical, Control and Communication Engineering 2, no. 1 (April 1, 2013): 40–46. http://dx.doi.org/10.2478/ecce-2013-0006.
Повний текст джерелаАнотація:
AbstractIn electric vehicle applications, it is necessary to use series strings of batteries since the required voltage is higher than the one that can be obtained from a single battery. Due to several factors, imbalance of batteries in these battery systems is usual and an important factor that has to be taken into account. Many balancing methods have been developed with a lot of different advantages, but all of them also have a lot of disadvantages such as complexity and/or high cost, which are the common problems that can be found in most of these equalization methods. In the present work, a low cost and very simple equalization method is proposed, in which a novel control is applied to a shunting transistor topology. It allows the transistors to regulate the amount of current that goes through each battery cell in the string depending on their State of Charge (SOC), during the charging process. This control ensures that the least charged cells to be charged faster, and the most charged ones to be charged more slowly. Design criteria are discussed and simulation results are carried out in a generic battery low power application which proves the control method. Fast equalization with a low complexity and cost is obtained
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Wang, Shun-Chung, Chun-Yu Liu, and Yi-Hua Liu. "A Non-Dissipative Equalizer with Fast Energy Transfer Based on Adaptive Balancing Current Control." Electronics 9, no. 12 (November 24, 2020): 1990. http://dx.doi.org/10.3390/electronics9121990.
Повний текст джерелаАнотація:
In this study, an active inductive equalizer with fast energy transfer based on adaptive balancing current control is proposed to rapidly equilibrate lithium-ion battery packs. A multiphase structure of equalizer formed by many specific parallel converter legs (PCLs) with bidirectional energy conversion serves as the power transfer stage to make the charge shuttle back and forth between the cell and sub-pack or sub-pack and sub-pack more flexible and efficient. This article focuses on dealing with the problem of slow balancing rate, which inherently arises from the reduction of balancing current as the voltage difference between the cells or sub-packs decreases, especially in the later period of equalization. An adaptive varied-duty-cycle (AVDC) algorithm is put forward here to accelerate the balance process. The devised method has taken the battery nonlinear behavior and the nonideality of circuit component into consideration and can adaptively modulate the duty cycle with the change of voltage differences to maintain balancing current nearly constant in the whole equilibrating procedure. Test results derived from simulations and experiments are provided to demonstrate the validity and effectiveness of the equalizer prototype constructed. Comparing with the conventional fixed duty cycle (FDC) method, the improvements of 68.3% and 8.3% in terms of balance time and efficiency have been achieved.
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Zhang, Rui, Honghua Xu, and Yibo Wang. "A Dynamic Priority Factor Loop for Fast Voltage Equalization Applied to High Power Density DC–DC Converter System." IEEE Transactions on Power Electronics 35, no. 1 (January 2020): 198–207. http://dx.doi.org/10.1109/tpel.2019.2915114.
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Farzan Moghaddam, Ali, and Alex Van den Bossche. "An Efficient Equalizing Method for Lithium-Ion Batteries Based on Coupled Inductor Balancing." Electronics 8, no. 2 (January 29, 2019): 136. http://dx.doi.org/10.3390/electronics8020136.
Повний текст джерелаАнотація:
This article developed a coupled inductor balancing method to overcome cell voltage variation among cells in series, for Lithium Ion (Li-ion) batteries in Electrical Vehicles (EV). For an "eight cells in series" example, the developed balance circuit has four inductors, one magnetic circuit with one winding per two cells, and one control switch per cell, as compared to the traditional inductor-based equalizer that needs N-1 inductors and magnetic circuits for N number of cells and more switches. Therefore, ultimately, a more efficient, cost-effective circuit and low bill of materials (BOM) will be built up. All switches are logic-level N-Channel metal-oxide-semiconductor field-effect transistors (MOSFETs) and they are controlled by a pair of complementary signals in a synchronous trigger pattern. In the proposed topology, less components and fast equalization are achieved compared to the conventional battery management system (BMS) technique for electrical vehicles based on the inductor balancing method. This scheme is suitable for fast equalization due to the inductor-based balancing method. The inductors are made with a well-chosen winding ratio and all are coupled with one magnetic core with an air gap. Theoretical derivation of the proposed circuit was well-presented, and numerical simulation relevant to the electrochemical storage devices was conducted to show the validity of the proposed balance circuit. A complete balance circuit was built to verify that the proposed circuit could resolve imbalance problems which existed inside battery modules.
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Roth, Thomas, Luiza Streck, Philip Niehoff, and Andreas Jossen. "Disturbances Due to Short- and Long-Term Diffusion Equalization Effects in Self-Discharge Measurements of Lithium-Ion Batteries." ECS Meeting Abstracts MA2022-02, no. 6 (October 9, 2022): 626. http://dx.doi.org/10.1149/ma2022-026626mtgabs.
Повний текст джерелаАнотація:
Quality assurance is essential for controlling lithium-ion cell properties during and after manufacturing. The largest contributors to process manufacturing costs of lithium-ion batteries are the cell formation and aging, when cell quality parameters are determined [1]. While voltage, capacity and impedance are determined reasonably fast, cell aging and self-discharge monitoring may take two to three weeks [2]. Apart from economical aspects for manufacturing and cell aging, accurately measuring the self-discharge may take up to several month [3, 4]. The main reason for the long duration of electrical self-discharge measurements are disturbances due to short-term and long-term diffusion equalization effects [5]. Short-term effects up to several hours include solid phase and liquid phase diffusion, leading to open circuit voltage relaxation [6]. Long-term effects up to several weeks are mainly based on the same diffusion phenomena in conjunction with inactive anode overhang areas [7]. Therefore, the storage condition has significant impact on the state-of-charge of the anode overhang, inducing anomalies with regard to capacity [8] and coulombic efficiency [9]. Consequently, it is expected that the aforementioned disturbances might have a similar effect on the electrical measurement of self-discharge. In this work, various cell preconditionings were applied to different methods for electrical self-discharge measurement, such as the capacity loss, the voltage decay and the voltage hold methods. The preconditioning allowed a distinction between undisturbed cells, short-term and long-term disturbed cells, or cells affected by a combination of disturbances. The investigated cells were commercial Samsung INR21700-50E cylindrical cells (NCA/silicon-graphite) and non-commercial pouch cells (NMC622/graphite) with comparable capacity and anode overhang areas. The results showed significant impact of preconditioning on the self-discharge measurements. Self-discharge of undisturbed cells was accurately measured within a few days. Short-term disturbances subsided after several hours, which is in good agreement with the findings from open circuit voltage relaxation [6]. Long-term disturbances due to the anode overhang areas decreased over the measurement period even though the self-discharge current was still many times higher than the undisturbed self-discharge after several weeks. Comparison to initial testing of non-commercial cells showed an equivalence of voltage decay method for fresh cells after formation and long-term disturbed cells, indicating anode overhang charge equalization as the main contributor to self-discharge measurements during cell aging step. The utilized non-commercial pouch cells were designed and produced within the scope of the project “FormEL”, funded by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0296D. Literature [1] Liu, Y.; Zhang, R.; Wang, J.; Wang, Y.: Current and future lithium-ion battery manufacturing, In: iScience 24 (4), p. 102332–102332, 2021 [2] Kwade, A.; Haselrieder, W.; Leithoff, R.; Modlinger, A.; Dietrich, F.; Droeder, K.: Current status and challenges for automotive battery production technologies, In: Nature Energy 3 (4), pp. 290–300, 2018 [3] Zilberman, I.; Sturm, J.; Jossen, A.: Reversible self-discharge and calendar aging of 18650 nickel-rich, silicon-graphite lithium-ion cells, In: Journal of Power Sources 425 (9), pp. 217–226, 2019 [4] Theiler, M.; Endisch, C.; Lewerenz, M.: Float Current Analysis for Fast Calendar Aging Assessment of 18650 Li(NiCoAl)O2/Graphite Cells, In: Batteries 7 (2), p. 22–22, 2021 [5] Deutschen, T.; Gasser, S.; Schaller, M.; Siehr, J.: Modeling the self-discharge by voltage decay of a NMC/graphite lithium-ion cell, In: Journal of Energy Storage 19 (8), pp. 113–119, 2018 [6] Kindermann, F.M.; Noel, A.; Erhard, S.V.; Jossen, A.: Long-term equalization effects in Li-ion batteries due to local state of charge inhomogeneities and their impact on impedance measurements, In: Electrochimica Acta 185, pp. 107–116, 2015 [7] Wilhelm, J.; Seidlmayer, S.; Keil, P.; Schuster, J.; Kriele, A.; Gilles, R.; Jossen, A.: Cycling capacity recovery effect: A coulombic efficiency and post-mortem study, In: Journal of Power Sources 365, pp. 327–338, 2017 [8] Burrell, R.; Zulke, A.; Keil, P.; Hoster, H.: Communication—Identifying and Managing Reversible Capacity Losses that Falsify Cycle Ageing Tests of Lithium-Ion Cells, In: Journal of The Electrochemical Society 167 (13), p. 130544–130544, 2020 [9] Gyenes, B.; Stevens, D.A.; Chevrier, V.L.; Dahn, J.R.: Understanding Anomalous Behavior in Coulombic Efficiency Measurements on Li-Ion Batteries, In: Journal of The Electrochemical Society 162 (3), A278-A283, 2015
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Barreras, Jorge Varela, Ricardo de Castro, Yihao Wan, and Tomislav Dragicevic. "A Consensus Algorithm for Multi-Objective Battery Balancing." Energies 14, no. 14 (July 15, 2021): 4279. http://dx.doi.org/10.3390/en14144279.
Повний текст джерелаАнотація:
Batteries stacks are made of cells in certain series-parallel arrangements. Unfortunately, cell performance degrades over time in terms of capacity, internal resistance, or self-discharge rate. In addition, degradation rates are heterogeneous, leading to cell-to-cell variations. Balancing systems can be used to equalize those differences. Dissipative or non-dissipative systems, so-called passive or active balancing, can be used to equalize either voltage at end-of-charge, or state-of-charge (SOC) at all times. While passive balancing is broadly adopted by industry, active balancing has been mostly studied in academia. Beyond that, an emerging research field is multi-functional balancing, i.e., active balancing systems that pursue additional goals on top of SOC equalization, such as equalization of temperature, power capability, degradation rates, or losses minimization. Regardless of their functionality, balancing circuits are based either on centralized or decentralized control systems. Centralized control entails difficult expandability and single point of failure issues, while decentralized control has severe controllability limitations. As a shift in this paradigm, here we present for the first time a distributed multi-objective control algorithm, based on a multi-agent consensus algorithm. We implement and validate the control in simulations, considering an electro-thermal lithium-ion battery model and an electric vehicle model parameterized with experimental data. Our results show that our novel multi-functional balancing can enhance the performance of batteries with substantial cell-to-cell differences under the most demanding operating conditions, i.e., aggressive driving and DC fast charging (2C). Driving times are extended (>10%), charging times are reduced (>20%), maximum cell temperatures are decreased (>10 °C), temperature differences are lowered (~3 °C rms), and the occurrence of low voltage violations during driving is reduced (>5×), minimizing the need for power derating and enhancing the user experience. The algorithm is effective, scalable, flexible, and requires low implementation and tuning effort, resulting in an ideal candidate for industry adoption.
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Gu, Youzhi, Xinjie Feng, Runze Chi, Jiangfeng Wu, and Yongzhen Chen. "A Digital Bang-Bang Clock and Data Recovery Circuit Combined with ADC-Based Wireline Receiver." Electronics 11, no. 21 (October 27, 2022): 3489. http://dx.doi.org/10.3390/electronics11213489.
Повний текст джерелаАнотація:
With the great increases in data transmission rate requirements, analog-to-digital converter (ADC)-based wireline receivers have received more and more attention due to their flexible and powerful equalization capabilities. Considering power consumption, baud-rate Mueller–Muller clock and data recovery (MM-CDR) circuits are widely used in ADC-based wireline receivers since MM-CDR circuits only need one sample signal per unit interval (UI). However, MM-CDR circuits need to set an additional Vref voltage to match the size of the main tap of the channel. If the Vref matching is not appropriate or the signal quality is good as a square wave, MM-CDR circuits cannot accurately lock on to a certain phase and instead drift within a phase range. Therefore, MM-CDR circuits are not as robust and stable as oversampled CDR circuits. In this study, a digital bang-bang clock and data recovery (DBB-CDR) circuit combined with an ADC-based wireline receiver was proposed. The DBB-CDR circuit could eliminate various unstable factors of MM-CDR circuits and achieve fast and robust phase locking without excessively increasing power consumption. A model of the DBB-CDR circuit was combined with an actual 32 Gb/s ADC-based wireline receiver, which was implemented in 28 nm CMOS technology to analyze the performance of the DBB-CDR circuit. The simulation results showed that the DBB-CDR circuit could achieve 0.42 UIpp JTOL@10MHz, and that the minimum JTOL value was 0.362 UIpp under a 0.04 UI variance of Gaussian jitter. The area and power consumption of the DBB-CDR circuit were only 64 μm2 and 0.02 mW, respectively; and the DBB-CDR circuit could also obtain very stable phase locking and demonstrated a fast frequency offset tracking ability when there was a frequency offset.
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Holmes, W. R., I. Segev, and W. Rall. "Interpretation of time constant and electrotonic length estimates in multicylinder or branched neuronal structures." Journal of Neurophysiology 68, no. 4 (October 1, 1992): 1401–20. http://dx.doi.org/10.1152/jn.1992.68.4.1401.
Повний текст джерелаАнотація:
1. We have investigated the theoretical and practical problems associated with the interpretation of time constants and the estimation of electrotonic length with equivalent cylinder formulas for neurons best represented as multiple cylinders or branched structures. Two analytic methods were used to compute the time constants and coefficients of passive voltage transients (and time constants of current transients under voltage clamp). One method, suitable for simple geometries, involves analytic solutions to boundary value problems. The other, suitable for neurons of any geometric complexity, is an algebraic approach based on compartmental models. Neither of these methods requires the simulation of transients. 2. We computed the time constants and coefficients of voltage transients for several hypothetical neurons and also for a spinal motoneuron whose morphology was characterized from serial reconstructions. These time constants and coefficients were used to generate voltage transients. Then exponential peeling, nonlinear regression, and transform methods were applied to these transients to test how well these procedures estimate the underlying time constants and coefficients. 3. For a serially reconstructed motoneuron with 732 compartments, we found that the theoretical and peeled tau 0 values were nearly equal, but the theoretical tau 1 was much larger than the peeled tau 1. The theoretical tau 1 could not be peeled because it was associated with a coefficient, C1, that had a very small value. In fact, there were 156 time constants between 1.0 and 6.0 ms, most of which had very small coefficients; none had a coefficient larger than 2% of the signal. The peeled value of tau 1 (called tau 1 peel) can be viewed as some sort of a weighted average of the time constants having the largest coefficients. 4. We studied simple hypothetical neurons to determine what interpretation could be applied to the multitude of theoretical time constants. We found that after tau 0, there was a group of time constants associated with eigenfunctions that were odd (or approximately odd) functions with respect to the soma. These time constants could be interpreted as "equalizing" time constants along particular paths between different pairs of dendritic terminals in the neuron. After this group of time constants, there was one that we call tau even because it was associated with an eigen-function that was approximately even with respect to the soma. This tau even could be interpreted as an equalizing time constant for charge equalization between proximal membrane (soma and proximal dendrites) and distal membrane (including all distal dendrites).4=
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Snijders, Jos, Peter de Bruijn, Marcel Bergmans, and Gijs Bastianen. "Study on causes and prevention of electrostatic charge build-up during extracorporeal circulation." Perfusion 14, no. 5 (September 1999): 363–70. http://dx.doi.org/10.1177/026765919901400508.
Повний текст джерелаАнотація:
For many years it has been known that roller pumps interfere regularly with the electrocardiogram (ECG) signal. This electrical activity is also considered responsible for the electrostatic charge build-up in some oxygenators with a plastic heat exchanger. During use of such an oxygenator, an electrical shock can be felt when touching the device. In the absence of a provoked discharge, a spontaneous discharge may occur. The construction of the heat exchanger and the use of nonconductive materials enable some devices to function as a capacitor. If the voltage difference across the fibre wall is too high, an electrostatic discharge may occur. In 1997, four blood-to-water leaks in Maxima Forté oxygenators were reported on a worldwide basis. After thorough research by Medtronic Cardiac Surgery (Cardiopulmonary Division), the cause of the leaks was found to be an electrothermal event across the fibre wall of one single fibre. No patient injuries were reported in any of the events. Medtronic patented a number of US Food and Drug Administration-approved and patient-safe solutions to prevent this electrostatic charge build-up. We studied the electrostatic phenomenon in order to clarify the clinical aspects. The in vitro part of the study is related to the behaviour of the Medtronic Biopump and the Stockert Shiley roller pump - in combination with the use of a PVC or silicone pumpheader. Subsequently, we have investigated the influence of the rotation or flow of both types of blood pumps and occlusion settings on the roller pump. Furthermore, we tried to capture the electrical charge generated by the roller pumps in a capacitor and in some oxygenators with different types of heat exchanger. Finally, we tested the external CEL™ (Charge Equalization Line) and the internal ‘Gold Wire’ charge equalization systems, both patented by Medtronic. In the in vivo part of the study, 15 patients were divided into three groups of five patients each. In the first group a roller pump with a PVC pumpheader was evaluated and, in the second group, a roller pump with a silicone pumpheader. The third group consisted of the Medtronic Biopump. In all the groups, a Maxima Forté oxygenator with the external CEL protection was used. Owing to the fact that, at the time, the Maxima Forté ‘Gold Wire’ oxygenator was not available for clinical use, only the external CEL could be evaluated.
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Gao, Changwei, Yongchang Sun, Weiqiang Zheng, and Wei Wang. "Transient power equalization control strategy of virtual synchronous generator in isolated island microgrid with heterogeneous power supply." Scientific Reports 13, no. 1 (August 3, 2023). http://dx.doi.org/10.1038/s41598-023-39121-6.
Повний текст джерелаАнотація:
AbstractIn the parallel supply system of synchronous generator and virtual synchronous generator, the physical structure and control structure of the two kinds of power supply are quite different, and it is difficult to distribute the transient power of the two kinds of power supply evenly when the load changes abruptly. Especially in the case of sudden load increase, virtual synchronous generator bears too much load in the transient process because of its fast adjustment speed, and even causes short-term overload, which makes the capacity of virtual synchronous generator can not be fully utilized. In view of this problem, firstly, the mechanism of transient power uneven distribution of two heterogeneous power sources is explained from the differences of frequency modulation, voltage regulation and output impedance. Secondly, virtual speed regulation, virtual excitation and dynamic virtual impedance are added to the traditional virtual synchronous generator control to simulate the speed regulation characteristics and electromagnetic transient characteristics of the synchronous generator, so as to realize the transient and steady-state power equalization between heterogeneous power supplies when the virtual synchronous generator and the synchronous generator run in parallel. Thirdly, in order to ensure the fast dynamic response characteristics of the virtual synchronous generator in independent operation mode, the traditional virtual synchronous generator control algorithm is still maintained in independent operation mode, and the mode switching control link based on state tracking is designed to realize smooth switching between the two working modes. Finally, the hardware in loop experiment results based on RT-LAB show that the proposed control method can realize the transient and steady-state power equalization when the virtual synchronous generator and the synchronous generator operate in parallel, it can keep the fast voltage regulation and frequency modulation ability when the virtual synchronous generator operates independently, and can realize smooth switching between independent and parallel operation modes.
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Lujun, Wang, Ke Jinyang, Zhan Min, Tian Aina, Wu Tiezhou, Zhang Xiaoxing, and Jiang Jiuchun. "Efficient and Fast Active Equalization Method for Retired Battery Pack Using Wide Voltage Range Bidirectional Converter and DBSCAN Clustering Algorithm." IEEE Transactions on Power Electronics, 2022, 1–9. http://dx.doi.org/10.1109/tpel.2022.3185242.
Повний текст джерела
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Putra, Dian Eka, and Randi Kusniriansya. "Analisa Pemerataan Beban Antar Fasa Di Saluran Tegangan Rendah (SUTR) Pada Transformator Distribusi 50 KVA - Li 146 Wilayah Kerja PT PLN (Persero) Rayon Muara Beliti." JURNAL SURYA ENERGY 4, no. 1 (December 12, 2019). http://dx.doi.org/10.32502/jse.v4i1.1883.
Повний текст джерелаАнотація:
ABSTRAKKetidak seimbangan beban yang terjadi SUTR terletak etidakteraturan pemasangan sambungan rumah (SR) baik satu fasa maupun tiga fasa pada saluran udara tegangan rendah mengakibatkan beban trasformator distribusi LI 146 menjadi tidak merata, hal ini dikarenakan adanya penumpukan beban pada salah satu fasa, sehingga beban saluran tidak seimbang. Ketidakseimbangan beban menyebabkan menyebabkan terjadinya lossesdaya listrik pada jaringan penghantar netral.Diawali dengan pengukuran setiap fasa SUTR maka didapat lapangan fasa R yang terbesar dengan Arus 41 Amperedan fasa T Arus terkecil sebesar 12.2 A, akibat dari perbedaan yang besar antar fasa minimbulakan arus sebesar 35,5 A. Maka diperlukananalisa perbaikan dilapangan untuk mengurangi besarnya arus netral dan loses yang terjadi maka dilakukan pemerataan beban dengan jalan perbaikan sambungan konduktordan pemindahan disetiap penghantar fasa pada beban berupa sambungan rumah (SR) dan beban lainya lampu penerangan jalan, dari jaringan fasa yang besar ke penghantar fasa yang lebih kecil.penelitian inididapatnilai besar arus netral dan rugi-rugi (losses)penghantar netral sebelum dan setelah dilakukan pemerataan beban saluran udara tegangan rendah (SUTR). Pengukuran dan perhitungan dilakukan pada luar waktu beban puncaktransformator distribusi pada gardu distribusi LI 146 di PT PLN (Persero) ULP Muara Beliti.Berdasarkan hasil perhitungan besar arus netral sebelum dilakukan pemerataan beban yaitu 35,5 A dan rugi-rugi yang terjadi akibat arus netral sebesar 2,265 kW. Namun setelah dilakukan pemerataan beban, besar arus netral berkurang menjadi 24,2 Adikarenakan arus netral berkurang maka rugi-rugi pada penghantar netral ikut berkurang menjadi 0,97 kW. Hal ini berarti bahwa program pemerataan beban dapat meminimalisir besar arus dan rugi-rugi daya (losses) yang timbul disaluran penghantar netral transformator distribusi LI 146.Kata kunci : Ketidakseimbangan beban, Transformator LI 146, Pemerataan beban saluran.ABSTRACThe load imbalance that occurs in SUTR lies in the irregularity of the installation of house connections (SR) both one phase and three phases in the low voltage air ducts causing the distribution load transformer LI 146 to be uneven, this is due to a buildup of load on one phase, so that the load is not balanced. The unbalance of load causes electrical power losses in the neutral conductor network. Beginning with the measurement of each phase of the SUTR, the largest phase R is obtained with a current of 41 Amperedan and T phase The smallest current of 12.2 A, due to a large difference between the phase minimbulakan currents of 35.5 A. Therefore, it is necessary to analyze the improvement in the field to reduce the amount of neutral current and loses that occur then the load equalization is carried out by repairing conductor connections and displacement in each phase conductor at loads in the form of house connections (SR) and other loads of street lighting, from large phase networks to conductors smaller phase. this research can be a large value of neutral current and neutral conductor losses before and after the equalization of low voltage air line loads (SUTR). Measurements and calculations are carried out outside the load time of the distribution transformer at the LI 146 distribution substation at PT PLN (Persero) ULP Muara Beliti. Based on the results of the calculation of neutral currents before equalization of the load ie 35.5 A and the losses incurred due to neutral currents of 2,265 kW. However, after the load is equalized, the neutral current is reduced to 24.2 Adik. Since the neutral current is reduced, the losses on neutral conductors also decrease to 0.97 kW. This means that the load equalization program can minimize the amount of current and power losses that arise in the distribution channel neutral distribution transformer LI 146.Keyword : Load imbalance, Transformer LI 146, Channel load equalization