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Koji Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Electric double‐layer capacitor module with series‐parallel reconfigurable Cell Voltage equalizers
Electrical Engineering in Japan, 2012Co-Authors: Masatoshi Uno, Akio Kukita, Koji TanakaAbstract:When electric double-layer capacitors (EDLCs) are connected in series, a Cell Voltage imbalance occurs due to nonuniform Cell properties. Cell Voltage imbalance should be minimized to prolong cycle lives and maximize the available energy of Cells. In this study, we propose a series-parallel reconfigurable Cell Voltage equalizer that is considered suitable for energy storage systems using EDLCs instead of traditional secondary batteries as the main energy storage sources. The proposed equalizer requires only EDLCs and switches as its main circuit elements, and it utilizes EDLCs not only for energy storage but also for equalization. An equivalent circuit model using equivalent resistors that can be regarded as an index of equalization speed is developed. Current distribution and Cell Voltage imbalancing during operation are quantitatively generalized. Experimental charge–discharge tests were performed on the EDLC modules to demonstrate the performance of the Cell Voltage equalizer. All the Cells in the modules could be charged/discharged uniformly even when a degradation-mimicking Cell was intentionally included in the module. The resultant Cell Voltage imbalances and current distributions were in good agreement with those predicted by mathematical analyses. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 38–50, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21287
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Single-switch Cell Voltage equalizer using Voltage multipliers for series-connected supercapacitors
2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2012Co-Authors: Masatoshi Uno, Koji TanakaAbstract:A novel single-switch Cell Voltage equalizer using Voltage multipliers for series-connected supercapacitors (SCs) is proposed. Since the proposed equalizer can operate with a single switch at a fixed duty cycle when operated in discontinuous conduction mode (DCM), the circuit complexity can be reduced significantly when compared with conventional equalizers, and can also eliminate feedback control. Operation analyses are made and a dc equivalent circuit is mathematically derived to prove the Voltage equalization mechanism. An experimental equalization test using the proposed equalizer operating with a fixed duty cycle was performed for series-connected SCs from an initially Cell-Voltage-imbalanced condition. The Cell Voltage imbalance was successfully eliminated with an average power conversion efficiency of 78.8%.
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single switch Cell Voltage equalizer using multistacked buck boost converters operating in discontinuous conduction mode for series connected energy storage Cells
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Koji TanakaAbstract:The Cell Voltage imbalance of series-connected energy storage Cells, such as supercapacitors (SCs) and lithium-ion Cells, causes premature deterioration and a decrease in the available energies of the Cells. Various equalization techniques have been developed for diminishing such imbalances. However, since the number of switches, sensors, and/or multiwinding transformers present in conventional equalizers is directly proportional to the number of series connections of the Cells, the circuit complexity and cost of the equalizers are prone to increase with the number of series connections. In this paper, single-switch Cell Voltage equalizers using multistacked buck-boost converters, such as the single-ended primary inductor converter (SEPIC), Zeta, and Cuk converters, are proposed. These equalizers consist of passive components and a single switch, significantly reducing the complexity of the circuit when compared with that of conventional equalizers. In addition, when the proposed equalizers operate in discontinuous conduction mode, feedback control is not required to limit currents flowing through Cells and circuit components. The proposed equalizers are compared with conventional topologies in terms of the number of active and passive components required. Operating analyses were conducted under both Cell-Voltage-balanced and -imbalanced conditions. Experimental equalization tests were performed for four series-connected SCs using the SEPIC-based single-switch equalizer. The energies of the series-connected SCs were preferentially redistributed by the equalizer to the Cell(s) having the lowest Voltage, resulting in the elimination of the Cell Voltage imbalance and subsequent uniformity of the Cell Voltages.
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single switch Cell Voltage equalizer using multistacked buck boost converters operating in discontinuous conduction mode for series connected energy storage Cells
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Masatoshi Uno, Koji TanakaAbstract:The Cell Voltage imbalance of series-connected energy storage Cells, such as supercapacitors (SCs) and lithium-ion Cells, causes premature deterioration and a decrease in the available energies of the Cells. Various equalization techniques have been developed for diminishing such imbalances. However, since the number of switches, sensors, and/or multiwinding transformers present in conventional equalizers is directly proportional to the number of series connections of the Cells, the circuit complexity and cost of the equalizers are prone to increase with the number of series connections. In this paper, single-switch Cell Voltage equalizers using multistacked buck-boost converters, such as the single-ended primary inductor converter (SEPIC), Zeta, and Cuk converters, are proposed. These equalizers consist of passive components and a single switch, significantly reducing the complexity of the circuit when compared with that of conventional equalizers. In addition, when the proposed equalizers operate in discontinuous conduction mode, feedback control is not required to limit currents flowing through Cells and circuit components. The proposed equalizers are compared with conventional topologies in terms of the number of active and passive components required. Operating analyses were conducted under both Cell-Voltage-balanced and -imbalanced conditions. Experimental equalization tests were performed for four series-connected SCs using the SEPIC-based single-switch equalizer. The energies of the series-connected SCs were preferentially redistributed by the equalizer to the Cell(s) having the lowest Voltage, resulting in the elimination of the Cell Voltage imbalance and subsequent uniformity of the Cell Voltages.
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Single-switch Cell Voltage equalizer based on multi-stacked SEPICs for series-connected energy storage Cells
2011 IEEE 33rd International Telecommunications Energy Conference (INTELEC), 2011Co-Authors: Masatoshi Uno, Koji TanakaAbstract:Cell Voltage equalizers are usually used for series-connected energy storage Cells, such as lithium-ion Cells and supercapacitors (SCs), to eliminate Cell Voltage imbalance that may cause premature deterioration and reduce the available energy of the Cells. Because conventional Cell Voltage equalizers are based on multiple individual dc-dc converters, the number of switches, sensors, and/or transformers increases proportionally with the number of series-connected energy storage Cells. As compared to conventional equalizers, a single-switch Cell Voltage equalizer based on multi-stacked single-ended primary inductor converters (SEPICs), which is proposed in this paper, can dramatically reduce circuit complexity because of its single-switch operation. Furthermore, feedback control can be eliminated when the equalizer is operated in discontinuous conduction mode (DCM). The fundamental operating principle and the equalization time are mathematically generalized in this paper. An experimental equalization test was performed for four series-connected SCs to demonstrate the equalization performance. The standard deviation of Cell Voltages decreased to approximately 1 mV at the end of the equalization process, thus verifying the proposed equalizer's performance.
Kai Sundmacher - One of the best experts on this subject based on the ideXlab platform.
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Advanced Study of Non-Uniform Cell Voltage Distribution for a PEMFC Stack
Journal of Fuel Cell Science and Technology, 2011Co-Authors: Shuang Zhai, Pengtao Sun, Fengxiang Chen, Su Zhou, Kai SundmacherAbstract:In this paper, a fully coupled non-isothermal, electrochemical, and transport 3D model for a 10-Cell PEMFC stack with coolant channels is constructed and implemented to examine and compare the influence factors to the stack performance. The first case to be considered is under different thermal operation conditions, including thermostatic, adiabatic, and heat exchange operation. The corresponding results show that a better uniformity and the largest stack output power density can be obtained under heat exchange operation. The other case is to compare the effects of heat transfer coefficients for different materials (ranging from 5 W/(m2 ·K) to 50 W/(m2 ·K)) on the spatial non-homogeneity of stack Voltage and output power density. Numerical results indicate that the degree of the non-uniformity of individual Cell Voltage can be minimized, and the output power density can be elevated to a certain degree when the heat transfer coefficient is set as 25 W/(m2 ·K). In addition, an attempt is carried out to investigate the changes of some important variables due to the tolerance stacking or performance degradation, where we assume some Cells’ contact resistance increases. We observe that a large jump of Cell Voltage and temperature occurs, which can be used as a detection signal for stack safety operation.
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spontaneous oscillations of Cell Voltage power density and anode exit co concentration in a pem fuel Cell
Physical Chemistry Chemical Physics, 2011Co-Authors: Hui Lu, Liisa Rihkostruckmann, Kai SundmacherAbstract:The spontaneous oscillations of the Cell Voltage and output power density of a PEMFC (with PtRu/C anode) using CO-containing H2 streams as anodic fuels have been observed during galvanostatic operating. It is ascribed to the dynamic coupling of the CO adsorption (poisoning) and the electrochemical CO oxidation (reactivating) processes in the anode chamber of the single PEMFC. Accompanying the Cell Voltage and power density oscillations, the discrete CO concentration oscillations at the anode outlet of the PEMFC were also detected, which directly confirms the electrochemical CO oxidation taking place in the anode chamber during galvanostatic operating.
Masatoshi Uno - One of the best experts on this subject based on the ideXlab platform.
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Cell Voltage Equalizer Using a Selective Voltage Multiplier with a Reduced Selection Switch Count for Series-Connected Energy Storage Cells
Electronics, 2019Co-Authors: Masatoshi Uno, Teruhisa Ueno, Koji YoshinoAbstract:Cell Voltage equalization is mandatory to eliminate Voltage imbalance of series-connected energy storage Cells, such as lithium-ion batteries (LIBs) and electric double-layer capacitors (EDLCs), to ensure years of safe operations. Although a variety of Cell equalizers using selection switches have been proposed, conventional techniques require numerous switches in proportion to the Cell count and are prone to complexity. This paper proposes a novel Cell Voltage equalizer using a selective Voltage multiplier. By embedding selection switches into the Voltage multiplier-based Cell Voltage equalizer, the number of selection switches can be reduced in comparison with that in conventional topologies, realizing the simplified circuit. A prototype for twelve Cells was built, and an equalization test using LIBs was performed. The Voltage imbalance decreased down to approximately 20 mV by the proposed equalizer, and the standard deviation of Cell Voltages at the end of the equalization test was as low as 10 mV, demonstrating its equalization performance.
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Electric double‐layer capacitor module with series‐parallel reconfigurable Cell Voltage equalizers
Electrical Engineering in Japan, 2012Co-Authors: Masatoshi Uno, Akio Kukita, Koji TanakaAbstract:When electric double-layer capacitors (EDLCs) are connected in series, a Cell Voltage imbalance occurs due to nonuniform Cell properties. Cell Voltage imbalance should be minimized to prolong cycle lives and maximize the available energy of Cells. In this study, we propose a series-parallel reconfigurable Cell Voltage equalizer that is considered suitable for energy storage systems using EDLCs instead of traditional secondary batteries as the main energy storage sources. The proposed equalizer requires only EDLCs and switches as its main circuit elements, and it utilizes EDLCs not only for energy storage but also for equalization. An equivalent circuit model using equivalent resistors that can be regarded as an index of equalization speed is developed. Current distribution and Cell Voltage imbalancing during operation are quantitatively generalized. Experimental charge–discharge tests were performed on the EDLC modules to demonstrate the performance of the Cell Voltage equalizer. All the Cells in the modules could be charged/discharged uniformly even when a degradation-mimicking Cell was intentionally included in the module. The resultant Cell Voltage imbalances and current distributions were in good agreement with those predicted by mathematical analyses. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 38–50, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21287
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Single-switch Cell Voltage equalizer using Voltage multipliers for series-connected supercapacitors
2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC), 2012Co-Authors: Masatoshi Uno, Koji TanakaAbstract:A novel single-switch Cell Voltage equalizer using Voltage multipliers for series-connected supercapacitors (SCs) is proposed. Since the proposed equalizer can operate with a single switch at a fixed duty cycle when operated in discontinuous conduction mode (DCM), the circuit complexity can be reduced significantly when compared with conventional equalizers, and can also eliminate feedback control. Operation analyses are made and a dc equivalent circuit is mathematically derived to prove the Voltage equalization mechanism. An experimental equalization test using the proposed equalizer operating with a fixed duty cycle was performed for series-connected SCs from an initially Cell-Voltage-imbalanced condition. The Cell Voltage imbalance was successfully eliminated with an average power conversion efficiency of 78.8%.
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single switch Cell Voltage equalizer using multistacked buck boost converters operating in discontinuous conduction mode for series connected energy storage Cells
IEEE Transactions on Vehicular Technology, 2011Co-Authors: Masatoshi Uno, Koji TanakaAbstract:The Cell Voltage imbalance of series-connected energy storage Cells, such as supercapacitors (SCs) and lithium-ion Cells, causes premature deterioration and a decrease in the available energies of the Cells. Various equalization techniques have been developed for diminishing such imbalances. However, since the number of switches, sensors, and/or multiwinding transformers present in conventional equalizers is directly proportional to the number of series connections of the Cells, the circuit complexity and cost of the equalizers are prone to increase with the number of series connections. In this paper, single-switch Cell Voltage equalizers using multistacked buck-boost converters, such as the single-ended primary inductor converter (SEPIC), Zeta, and Cuk converters, are proposed. These equalizers consist of passive components and a single switch, significantly reducing the complexity of the circuit when compared with that of conventional equalizers. In addition, when the proposed equalizers operate in discontinuous conduction mode, feedback control is not required to limit currents flowing through Cells and circuit components. The proposed equalizers are compared with conventional topologies in terms of the number of active and passive components required. Operating analyses were conducted under both Cell-Voltage-balanced and -imbalanced conditions. Experimental equalization tests were performed for four series-connected SCs using the SEPIC-based single-switch equalizer. The energies of the series-connected SCs were preferentially redistributed by the equalizer to the Cell(s) having the lowest Voltage, resulting in the elimination of the Cell Voltage imbalance and subsequent uniformity of the Cell Voltages.
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Single-switch Cell Voltage equalizer based on multi-stacked SEPICs for series-connected energy storage Cells
2011 IEEE 33rd International Telecommunications Energy Conference (INTELEC), 2011Co-Authors: Masatoshi Uno, Koji TanakaAbstract:Cell Voltage equalizers are usually used for series-connected energy storage Cells, such as lithium-ion Cells and supercapacitors (SCs), to eliminate Cell Voltage imbalance that may cause premature deterioration and reduce the available energy of the Cells. Because conventional Cell Voltage equalizers are based on multiple individual dc-dc converters, the number of switches, sensors, and/or transformers increases proportionally with the number of series-connected energy storage Cells. As compared to conventional equalizers, a single-switch Cell Voltage equalizer based on multi-stacked single-ended primary inductor converters (SEPICs), which is proposed in this paper, can dramatically reduce circuit complexity because of its single-switch operation. Furthermore, feedback control can be eliminated when the equalizer is operated in discontinuous conduction mode (DCM). The fundamental operating principle and the equalization time are mathematically generalized in this paper. An experimental equalization test was performed for four series-connected SCs to demonstrate the equalization performance. The standard deviation of Cell Voltages decreased to approximately 1 mV at the end of the equalization process, thus verifying the proposed equalizer's performance.
Hirotaka Koizumi - One of the best experts on this subject based on the ideXlab platform.
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double input bidirectional dc dc converter using Cell Voltage equalizer with flyback transformer
IEEE Transactions on Power Electronics, 2015Co-Authors: Tasuku Anno, Hirotaka KoizumiAbstract:In this paper, a double-input bidirectional dc/dc converter that uses a rechargeable battery and an ultracapacitor (UC) is proposed. This converter is connected to a Cell-Voltage equalizer between the battery and UC. The Cell-Voltage equalizer enables Cell-Voltage equalization and energy transfer between the battery and UC. This converter has six operational modes. These modes are investigated by reduced-power-scale circuit experiment. In addition, the circuit operation under the combination of the six modes is verified using a PSIM simulator in a large power scale.
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IECON - Modularized LC resonant switched capacitor Cell Voltage equalizer
IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, 2014Co-Authors: Takuya Ohno, Takahumi Suzuki, Hirotaka KoizumiAbstract:Electric Vehicle (EV) and Hybrid EV (HEV) require higher Voltage than what a single storage Cell can output, so a large number of Cells are needed to be connected in series. For the series connected storage Cells, the Voltage equalizer is required. In this paper, modularized LC resonant switched capacitor Cell Voltage equalizer is proposed. By means of modularizing and Zero Current Switching (ZCS), the proposed equalizer reduces the equalization time and switching losses.
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IECON - Bidirectional chopper using Cell Voltage equalizing with flyback transformer
IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013Co-Authors: Tasuku Anno, Hirotaka KoizumiAbstract:Recently, the technology on electric vehicle (EV) is more and more focused. In order to control the motor driving, power conversion circuits are applied, and as the energy storage, rechargeable battery and electric double layer capacitor (EDLC) are generally used. The energy storage is composed of series connected Cells to get high output Voltage, therefore Cell Voltage unbalance occurs by means of the unequal characteristic of each Cell. To avoid the Voltage unbalance, several Voltage equalizing circuits have been proposed. In this paper, motor driving circuit using hybrid energy storage is proposed. This circuit has two sets of energy storages, and enables Cell Voltage equalization and energy transfer among energy storages. In proposed circuit, flyback transformer is connected to each energy storage Cell. The circuit operation has been confirmed by reduced scale circuit experiment.
Hui Lu - One of the best experts on this subject based on the ideXlab platform.
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spontaneous oscillations of Cell Voltage power density and anode exit co concentration in a pem fuel Cell
Physical Chemistry Chemical Physics, 2011Co-Authors: Hui Lu, Liisa Rihkostruckmann, Kai SundmacherAbstract:The spontaneous oscillations of the Cell Voltage and output power density of a PEMFC (with PtRu/C anode) using CO-containing H2 streams as anodic fuels have been observed during galvanostatic operating. It is ascribed to the dynamic coupling of the CO adsorption (poisoning) and the electrochemical CO oxidation (reactivating) processes in the anode chamber of the single PEMFC. Accompanying the Cell Voltage and power density oscillations, the discrete CO concentration oscillations at the anode outlet of the PEMFC were also detected, which directly confirms the electrochemical CO oxidation taking place in the anode chamber during galvanostatic operating.