BATTERIES | Parallel and Series Connections

An assembly accuracy analysis approach of mechanical assembly involving parallel and serial connections considering form defects and local surface deformations

To study the heating performance of a solar-assisted cold-water phase-change-energy heat pump system, its heating performance under series and parallel connections is simulated for a community in Harbin, the influence of ice thickness on the different operation modes is analyzed, and the economy of the system is calculated for series and parallel connections in this paper. The results show that the water supply temperature is higher and more uniform in the parallel operation, and more terminal heat is supplied; the ice thickness has more of an influence on the series connection compared to the parallel connection; and the dynamic payback period is 6.72 years for the series connection and 7.28 years for the parallel connection. This case study can serve as a guide for practical engineering application projects and act as a reference for heating and economic data for the promotion of this heat pump system.

Extracorporeal membrane oxygenation (ECMO) is an important rescue therapy method for the treatment of severe hypoxic lung injury. In some cases, oxygen saturation and oxygen partial pressure in the arterial blood are low despite ECMO therapy. There are case reports in which patients with such instances of refractory hypoxemia received a second membrane lung, either in series or in parallel, to overcome the hypoxemia. It remains unclear whether the parallel or serial connection is more effective. Therefore, we used an improved version of our full-flow ECMO mock circuit to test this. The measurements were performed under conditions in which the membrane lungs were unable to completely oxygenate the blood. As a result, only the photometric pre- and post-oxygenator saturations, blood flow and hemoglobin concentration were required for the calculation of oxygen transfer rates. The results showed that for a pre-oxygenator saturation of 45% and a total blood flow of 10 L/min, the serial connection of two identical 5 L rated oxygenators is 17% more effective in terms of oxygen transfer than the parallel connection. Although the idea of using a second membrane lung if refractory hypoxia occurs is intriguing from a physiological point of view, due to the invasiveness of the solution, further investigations are needed before this should be used in a wider clinical setting.

Since independent control of an AC machine requires only two currents, additional degrees of freedom that exist in multiphase (n>3) machines can be used for other purposes. One possibility is the series connection of the stator windings, in an appropriate manner, which enables independent control of a set of machines although a single multiphase voltage-source inverter (VSI) is used as the supply. The concept has been explored recently in a considerable depth. This paper examines an alternative to the series connection, parallel connection of a multitude of multiphase machines supplied from a single VSI. This eliminates a shortcoming of the series arrangement, the requirement to have open-end stator winding machines. The general principles of paralleling the multiphase machines to a single multiphase VSI are at first set forth, with the subsequent development concentrating on the two-motor five-phase drive system. Dynamic and steady-state models of the two-motor drive are developed, and the vector control scheme is explained. Theoretical findings are verified by extensive experimental investigation on a laboratory setup. It is shown that parallel-connected multiphase multimotor drives represent an advanced example of the well-known analogy between series and parallel connection in electrical engineering. The quality of dynamic performance is the same as with series-connected drive systems. However, parallel connection suffers from a number of serious shortcomings that will prevent its application in industry.

Rod-type metal corrosion probes based on electromechanical impedance (EMI) technique can quantitatively assess the amount of corrosion, which have a promising application in pipeline corrosion monitoring and have received much more attention. In the field of structural health monitoring, the EMI technique based on series and parallel connections has been widely studied and is very promising, but it is yet to be used in the probe design. In this work, a kind of novel metal corrosion probe with two piezoelectric elements in series and parallel connections was proposed, and its performance was investigated comprehensively by combining theoretical analysis with experiment research. Theoretical models of the proposed probe in the longitudinal vibration mode for both series and parallel connections were established, and verified by the experimental results. Influences of the thicknesses of piezoelectric layer and ceramic layer on the probe performance were analyzed. Artificial quantitative corrosion tests and accelerated corrosion tests were designed to evaluate the quantitative corrosion monitoring capacity. Temperature sensitivity tests were conducted to study the temperature dependence. The wireless impedance measurement was performed to confirm the online monitoring ability. Comparisons for the probe performance between the series and parallel connections were also presented. This work provided a comprehensive understanding for this kind of novel probe, which is beneficial to develop low-cost, high-precision, high-stability pipeline corrosion real-time monitoring technology.

Experimental and numerical analysis of oily wastewater treatment using low-cost mineral adsorbent in a single and multi-fixed bed column

The present study examined optimized anodic electrode materials microbial fuel cells (MFCs) with Jashore Municipal Wastewater (JMW) as substrate in series and parallel connections. Three anodic materials, Iron plate (Fe), Carbon felt (CF), and Graphite rod (GR), were used to get green energy from waste biomass in microbial fuel cells. The output voltage, current, and power density of MFC were measured to investigate the preeminent anodic electrode material. The optimized anodic electrode material was Fe owing to high voltage generation followed by CF and GR. Results further indicated that the output voltage increased, but current density, as well as power density, decreased in series connection due to the increase of internal resistance compared to parallel at Fe-Cu combination. The maximum voltage, current density, and power density in series connection were 2238 mV, 79.98 mA/m2, and 108.850 mW⁄m2, respectively. On the other hand, in parallel connection, those values were 793 mV, 248.272 mA/m2, and 115.943 mW⁄m2, respectively. Most small electrical devices need high currents rather than high voltage imply parallel connections are preferred in this regard. Moreover, Fe-Cu combination is better to remove (87%) organic matter regarding COD removal efficiency from wastewater of MFCs.

The objective of this study is to explore the harvest maximum output changes occurs in piezoelectric transducer when connected in different configuration to produce highest electricity consumption and generate sound energy harvesting system. Acoustic energy is a type of environmental energy source that can be extracted and converted into electrical energy for small-scale energy applications. In this study, the corresponding load resistance for single piezoelectric transducer is 4.5 k$\Omega$, together with a constant vibration source at a frequency of 68 Hz and a 1-g acceleration. The performance of output voltage and power of piezoelectric are evaluated and the optimum output is measured by depending on the connection of the piezoelectric transducer arrangement into series, parallel and series, and parallel which stimulated using Proteus software. The experiment result presented that, when have single piezo, 5 piezo connected in series, and 5 piezo connected in parallel, the output powers are 1.664 mW, 1.671mW and 7.676 mW, respectively. During the combination series and parallel connections, the output power of 3S1P piezo increases to 5.05mW. In a parallel configuration, the output voltage that produced is much higher than a piezoelectric transducer arrangement connected in series connection. The piezoelectric transducer that connected in parallel configurations increases its voltage output from 2.83 V to 13.05 V with the same polarity. The arrangement of piezoelectric transducer in parallel configuration is affordable, with its higher production of a higher power output compared to the arrangement of piezoelectric transducer in series connection. Whereas in terms of power output, the maximum power remains constant in the range of 1.665 to 1.671 mW when three transducers are in series configuration connection with the same polarity. In conclusion, the proper implementation of the piezoelectric array configuration is needed in order to operate the minimum energy for low load devices and promise to accomplish generated optimum power output in harvester system.

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Contribution:</i> A new operational definition of series connections is given based on elements belonging to the same two meshes, which is properly dual to the usual definition of parallel elements being connected to the same two nodes. Furthermore, computer-based exercises have been developed and tested to teach students about such connections in gateway linear circuits courses, using color coding of nodes and meshes as a pedagogical device. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Background:</i> Series and parallel connections are a crucial but difficult concept. Existing textbooks give them limited attention, resulting in later difficulties learning circuit analysis. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Research Questions:</i> RQ1: Can an improved definition of series elements aid student understanding and student satisfaction? RQ2: Can a computer-based “game” lead to effective mastery and student satisfaction at a wide range of institutions, including minority-serving ones? <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Methodology:</i> Standard and new definitions were elaborated in a multiple-choice tutorial. A game was developed focusing on identifying series and parallel connections, with color coding of both nodes and meshes. Student learning was assessed over eight years using pretest and posttest in 14 varied institutions. Student opinions were assessed using several types of surveys. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Findings:</i> Strong learning gains were observed every semester from built-in pretest and posttest, with average scores of 28% and 87%, respectively. Large improvements were observed at every institution including five minority-serving ones. The posttest score is increased by a statistically significant amount after introducing the new definition of series elements. Students preferred the new definition of series and recommended its use, and very strongly endorsed color coding.

This paper presents a novel non-uniform time-step (NUTS) fundamental locally one-dimensional (FLOD) finite-difference time-domain (FDTD) method for multiconductor transmission lines (MTLs) including lumped elements. The NUTS scheme adopts different (non-uniform) time steps for different periods during simulation, in order to reduce the large errors caused by unconditionally stable FDTD methods with uniform time step larger than Courant-Friedrichs-Lewy limit. It is found that NUTS scheme is potentially unstable for alternating-direction-implicit (ADI) FDTD method, but it is stable for LOD-FDTD method or its implementation based on fundamental (FLOD) scheme. The NUTS FLOD-FDTD method is useful to simulate MTLs with lumped elements including resistor, capacitor, and inductor in series and parallel connections. Moreover, the method based on multiple 1-D approach is also extended to incorporate lumped elements in cross connection to model near-field coupling between the MTLs. While the electric current density is commonly used for field-circuit coupling of parallel connected lumped elements, the magnetic current density will be utilized for field-circuit coupling of series and cross-connected lumped elements. Numerical results for MTLs with lumped elements in series, parallel, and cross connections are provided to show the trade-off between efficiency and accuracy of the proposed NUTS FLOD-FDTD method. Compared with the FLOD-FDTD method with uniform time step, the NUTS FLOD-FDTD method may achieve higher accuracy by using smaller time step for certain periods of simulation.

The LED is attracting attention in lighting market as advantages such as long life and low power consumption. As a LED has a limitation on the brightness per cell, multiple LEDs are used. Therefore, the multi-path consisting of several LEDs is used variously depending on the application. There are parallel and serial connections in multiple output LED. The brightness and quality of LED module are affected by current, and parallel configuration has a disadvantage of current matching. However, the parallel connection has a advantage that remaining LEDs are turned on , even though some LEDs are out of order. The serial configuration has a advantage of accurate current matching. However, the serial configuration has a disadvantage that whole LEDs are turned off, even though one LED is out of order. This paper proposes a multi-path LED driver circuit including the protection circuit. The proposed circuit has the advantages of the serial connection, and overcomes the disadvantages of the serial connection with the protection circuit. To verify the performance of the proposed circuit, simulation and experimental results were carried out.

Over the past years Lithium-ion battery (LIB) has been widely used in the electric devices such as notebooks, cell phones, and electric vehicles. For the demand of electric vehicles, LIB cells would be connected in series and parallel to achieve a high voltage and capacity. However, connected batteries will cause some negative effects on the battery pack performance. For example, battery pack with mismatching internal resistance of cells in parallel connection will induce unbalance temperature and cause cycle life reduction [1]. Therefore, the development of an effective simulation model, which is able to predict the performance of cell pack, to help the electric vehicle designers to know the pack performance in advance is fundamentally needed. In the previous work [2], we have developed an electrochemical model to simulate the behavior of battery in series connection and have discussed about the effect on cell pack with uneven temperature distribution. However, due to possible difference in the internal resistance for each cell, current flowing through one cell is different from the other cell when the two cells are parallel connected. To deal with the issue of parallel connection of LIBs, Guo and White [3] have presented an initialization step, called self-balancing, to satisfy the constraint of equal open circuit voltage (OCV), which required that the cells in parallel connection should have the same voltage at any time. In the current study, we propose an alternative model, which combines the porous electrode theory and an algorithm. This algorithm helps us to calculate and distribute the instant current through each cell in the configuration of parallel connection. Figure 1 presents the discharge curves for a single 5Ah lithium manganese dioxide (LiMnO2) cell and three identical 5Ah LiMnO2 parallel-connected cells. The capacity of the cell pack is three times greater than the single cell. The amount of current through each cell is shown in figure 2, in which a slight fluctuation of the three currents can be observed. The small fluctuation could come from the small change in the slope of discharge curve around the capacity 10.5Ah, which leads to a deviation from a uniform current distribution in the pack. When the value of the current changes sharply, the discharge of the cell pack will stop. In order to discuss the aging effect on the performance of cell pack, we consider a particular scenario in which three cells are parallel connected with different initial state of charge (SOC) of 100, 90 and 80, respectively. Figure 3 displays the simulation result, which shows that the battery pack composed of different degree of aging cells presents a poorer performance than the pack with three identical cells. REFERENCES [1] R. Gogoana, M.B. Pinson, M.Z. Bazant, and S.E. Sarma, J. Power Source s 252, (2014) 8. [2] K.C. Chiu, C.H. Lin, S.F. Yeh, Y.H. Lin, C.S. Huang, and K.C. Chen, J. Power Sources, 263, (2014) 75. [3] M. Guo and R.E. White, J. Electrochem. Soc. 158, (2011) A1166. Figure 1

We investigated the operational characteristics of the hybrid-type superconducting fault current limiter (SFCL) according to the number of secondary windings. The SFCL consists of a transformer, which has a primary winding and several secondary windings with serially connected YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> films. In order to increase the capacity of the SFCL, the serial connection between each current limiting unit is necessary. Resistive-type SFCL has a difficulty in quenching simultaneously between the units due to slight differences of their critical current densities. The hybrid-type SFCL could achieve the simultaneous quenching through the electrical isolation and the mutual flux linkage among the units. We confirmed that the capacity of the SFCL could be increased effectively through the simultaneous quenching among the units. In addition, the power burden of the system could be reduced by adjusting the number of secondary windings. We will investigate the method to increase the capacity through serial and parallel connections among current limiting units

The triple-layered multimorph piezoelectric acoustic actuators were fabricated and studied to investigate the effects of the electrical configurations of the piezoelectric ceramics on the voltage-displacement and frequency response characteristics. The serial and parallel polarized piezoelectric multimorph ceramics were electrically connected in two different configurations of series and parallel, respectively: the serial multimorph in series connection (SMS), the serial multimorph in parallel connection (SMP), the parallel multimorph in series connection (PMS), and the parallel multimorph in parallel connection (PMP). Then, the vibrational displacement characteristics for each type of the triple layered multimorph ceramics were investigated by Finite Element Analysis (FEA) simulation and Laser Scanning Vibrometer (LSV) measurement. The maximum resonant displacements for SMS and PMP types were measured as 2.37 and 3.6 μm, respectively, which are at least 4.8 times higher than for SMP and PMS types. These LSV measured results were relatively in good agreement with the FEA simulated results. Moreover, due to these larger displacement characteristics, the piezoelectric acoustic actuators fabricated with the ceramics of SMS and PMP types had very high average SPLs of 83.1 dB and 85.7 dB at a distance of 10 cm away, respectively, which provide over 20 dB higher sound pressures than those for SMP and PMS types.

Resonant converters of 50(60) Hz AC-DC are described, where each half-cycle of network voltage of the capacitor and inductor of an oscillatory circuit are switched from series into parallel and vice versa. The duration of series and parallel connection and also the transformer ratio are parametrically dependent on load. In the case of the short circuit only the parallel oscillating circuit operates. This sharply restricts the output current. The reactive power of the capacitor and the inductor compensate with each other both in the case of series and parallel connection. Therefore the power factor is very high from no-load to short-circuit. This converter fits very well to supply arc furnaces. Then there is no need for the costly and fast reactive power compensator and filter circuits. The operating principle of the converter, design principles and a real operating converter rated 8.4 MW supplying a steel-melting arc furnace are described.