The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Masatoshi Uno - One of the best experts on this subject based on the ideXlab platform.
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single switch single magnetic pwm converter integrating voltage equalizer for partially shaded photovoltaic modules in standalone applications
IEEE Transactions on Power Electronics, 2018Co-Authors: Masatoshi Uno, Akio KukitaAbstract:To prevent partial-shading issues in photovoltaic (PV) systems, various kinds of voltage Equalizers that virtually unify characteristics of shaded and unshaded modules have been proposed. Although PV string utilization can be dramatically improved, PV systems tend to be complex and costly because, in addition to the main converter for string control, voltage Equalizers are separately necessary. This paper proposes the single-switch single-magnetic pulse width modulation (PWM) converter integrating the voltage equalizer using the series-resonant voltage multiplier (SRVM) for standalone PV systems. By utilizing a square wave voltage generated across a filter inductor in a PWM buck converter for driving the SRVM, the main PWM converter and voltage equalizer can be integrated into a single unit with reducing the total switch and magnetic component counts, achieving not only system-level but also circuit-level simplifications. The experimental test using the prototype for three PV modules connected in series was performed emulating a partial-shading condition. The integrated converter effectively precluded the partial-shading issues and significantly improved the power available at a load, demonstrating its efficacy.
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single switch voltage equalizer using multistacked buck boost converters for partially shaded photovoltaic modules
IEEE Transactions on Power Electronics, 2015Co-Authors: Masatoshi Uno, Akio KukitaAbstract:Partial shading on a photovoltaic (PV) string comprising multiple modules/substrings triggers issues such as a significant reduction in power generation and the occurrence of multiple maximum power points (MPPs), including a global and local MPPs, that encumber MPP tracking algorithms. Single-switch voltage Equalizers using multistacked buck–boost converters are proposed to settle the partial shading issues. The single-switch topology can considerably simplify the circuitry compared with conventional Equalizers requiring multiple switches in proportion to the number of PV modules/substrings. The proposed voltage Equalizers can be derived by stacking capacitor–inductor–diode filters on traditional buck–boost converters, such as SEPIC, Zeta, and Cuk converters. The optimum equalization strategy is also proposed and discussed for the Equalizers to compensate the partially shaded PV modules efficiently. Operational analysis based on a simplified equivalent circuit is performed for a SEPIC-based topology. Experimental equalization tests using the SEPIC-based voltage equalizer were performed emulating partially shaded conditions for a PV panel comprising of three substrings. Local MPPs were eliminated and extractable maximum powers increased by the equalizer, demonstrating the efficacy of the proposed voltage equalizer.
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single switch single transformer cell voltage equalizer based on forward flyback resonant inverter and voltage multiplier for series connected energy storage cells
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Masatoshi Uno, Akio KukitaAbstract:Cell voltage equalization is inevitable to ensure years of safe operation of series-connected energy storage cells, such as lithium-ion batteries and supercapacitors (SCs). Although various kinds of cell voltage Equalizers have been proposed, most equalizer topologies require multiple switches and/or a multiwinding transformer, resulting in complex circuitry and poor modularity. In this paper, a single-switch single-transformer equalizer using a forward-flyback resonant inverter (FFRI) with a voltage multiplier is proposed. The required switch count of the proposed equalizer is the minimum without impairing modularity due to the single-switch circuitry with no need for a multiwinding transformer. An experimental equalization test performed for eight SCs connected in series successfully demonstrated the equalization performance of the proposed equalizer. The FFRI can be extended as a “resonant input cell,” and by combining one of resonant input cells and a voltage multiplier, a single-switch resonant equalization charger that is basically a charger with an equalization function is also derived. An experimental charging test using the resonant equalization charger was also performed, and its equalization-charging performance was demonstrated.
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double switch equalizer using parallel or series parallel resonant inverter and voltage multiplier for series connected supercapacitors
IEEE Transactions on Power Electronics, 2014Co-Authors: Masatoshi Uno, Akio KukitaAbstract:A double-switch cell voltage equalizer using a parallel-resonant-inverter (PRI) or series-parallel-resonant inverter (SPRI) and voltage multiplier is proposed for series-connected supercapacitors (SCs), such as electric double-layer capacitors (EDLCs) and lithium-ion capacitors. The double-switch operation without the need for a multiwinding transformer offers simpler circuitry as well as better modularity than conventional Equalizers requiring multiple switches and/or a multiwinding transformer. Furthermore, the inherent constant current characteristic of the PRI/SPRI at a fixed frequency, not only removes the need for feedback control to limit currents under desired levels but the proposed equalizer can also operate safely, even when some cell voltage is 0 V. Detailed operation analyses were separately performed for the voltage multiplier and PRI/SPRI, and a dc equivalent circuit for the proposed equalizer was mathematically derived. A 10-W prototype for 12 cells connected in series was built, and an experimental equalization test was performed for EDLCs from an initially voltage imbalanced condition. Voltage imbalance of the series-connected EDLCs was successfully eliminated by the equalizer, demonstrating the equalization performance of the proposed equalizer.
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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.
Akio Kukita - One of the best experts on this subject based on the ideXlab platform.
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single switch single magnetic pwm converter integrating voltage equalizer for partially shaded photovoltaic modules in standalone applications
IEEE Transactions on Power Electronics, 2018Co-Authors: Masatoshi Uno, Akio KukitaAbstract:To prevent partial-shading issues in photovoltaic (PV) systems, various kinds of voltage Equalizers that virtually unify characteristics of shaded and unshaded modules have been proposed. Although PV string utilization can be dramatically improved, PV systems tend to be complex and costly because, in addition to the main converter for string control, voltage Equalizers are separately necessary. This paper proposes the single-switch single-magnetic pulse width modulation (PWM) converter integrating the voltage equalizer using the series-resonant voltage multiplier (SRVM) for standalone PV systems. By utilizing a square wave voltage generated across a filter inductor in a PWM buck converter for driving the SRVM, the main PWM converter and voltage equalizer can be integrated into a single unit with reducing the total switch and magnetic component counts, achieving not only system-level but also circuit-level simplifications. The experimental test using the prototype for three PV modules connected in series was performed emulating a partial-shading condition. The integrated converter effectively precluded the partial-shading issues and significantly improved the power available at a load, demonstrating its efficacy.
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single switch voltage equalizer using multistacked buck boost converters for partially shaded photovoltaic modules
IEEE Transactions on Power Electronics, 2015Co-Authors: Masatoshi Uno, Akio KukitaAbstract:Partial shading on a photovoltaic (PV) string comprising multiple modules/substrings triggers issues such as a significant reduction in power generation and the occurrence of multiple maximum power points (MPPs), including a global and local MPPs, that encumber MPP tracking algorithms. Single-switch voltage Equalizers using multistacked buck–boost converters are proposed to settle the partial shading issues. The single-switch topology can considerably simplify the circuitry compared with conventional Equalizers requiring multiple switches in proportion to the number of PV modules/substrings. The proposed voltage Equalizers can be derived by stacking capacitor–inductor–diode filters on traditional buck–boost converters, such as SEPIC, Zeta, and Cuk converters. The optimum equalization strategy is also proposed and discussed for the Equalizers to compensate the partially shaded PV modules efficiently. Operational analysis based on a simplified equivalent circuit is performed for a SEPIC-based topology. Experimental equalization tests using the SEPIC-based voltage equalizer were performed emulating partially shaded conditions for a PV panel comprising of three substrings. Local MPPs were eliminated and extractable maximum powers increased by the equalizer, demonstrating the efficacy of the proposed voltage equalizer.
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single switch single transformer cell voltage equalizer based on forward flyback resonant inverter and voltage multiplier for series connected energy storage cells
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Masatoshi Uno, Akio KukitaAbstract:Cell voltage equalization is inevitable to ensure years of safe operation of series-connected energy storage cells, such as lithium-ion batteries and supercapacitors (SCs). Although various kinds of cell voltage Equalizers have been proposed, most equalizer topologies require multiple switches and/or a multiwinding transformer, resulting in complex circuitry and poor modularity. In this paper, a single-switch single-transformer equalizer using a forward-flyback resonant inverter (FFRI) with a voltage multiplier is proposed. The required switch count of the proposed equalizer is the minimum without impairing modularity due to the single-switch circuitry with no need for a multiwinding transformer. An experimental equalization test performed for eight SCs connected in series successfully demonstrated the equalization performance of the proposed equalizer. The FFRI can be extended as a “resonant input cell,” and by combining one of resonant input cells and a voltage multiplier, a single-switch resonant equalization charger that is basically a charger with an equalization function is also derived. An experimental charging test using the resonant equalization charger was also performed, and its equalization-charging performance was demonstrated.
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double switch equalizer using parallel or series parallel resonant inverter and voltage multiplier for series connected supercapacitors
IEEE Transactions on Power Electronics, 2014Co-Authors: Masatoshi Uno, Akio KukitaAbstract:A double-switch cell voltage equalizer using a parallel-resonant-inverter (PRI) or series-parallel-resonant inverter (SPRI) and voltage multiplier is proposed for series-connected supercapacitors (SCs), such as electric double-layer capacitors (EDLCs) and lithium-ion capacitors. The double-switch operation without the need for a multiwinding transformer offers simpler circuitry as well as better modularity than conventional Equalizers requiring multiple switches and/or a multiwinding transformer. Furthermore, the inherent constant current characteristic of the PRI/SPRI at a fixed frequency, not only removes the need for feedback control to limit currents under desired levels but the proposed equalizer can also operate safely, even when some cell voltage is 0 V. Detailed operation analyses were separately performed for the voltage multiplier and PRI/SPRI, and a dc equivalent circuit for the proposed equalizer was mathematically derived. A 10-W prototype for 12 cells connected in series was built, and an experimental equalization test was performed for EDLCs from an initially voltage imbalanced condition. Voltage imbalance of the series-connected EDLCs was successfully eliminated by the equalizer, demonstrating the equalization performance of the proposed equalizer.
Koji Tanaka - One of the best experts on this subject based on the ideXlab platform.
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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.
Shlomi Arnon - One of the best experts on this subject based on the ideXlab platform.
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multiuser diffuse indoor wireless infrared communication using equalized
2006Co-Authors: Uri N Griner, Shlomi ArnonAbstract:We propose an indoor wireless infrared downlink scheme for high-data-rate multiuser connectivity with diffuse channels. The scheme is based on synchronous code-division multiple access with unipolar Hadamard codes. The orthogonality of unipolar Hadamard codes enables multiuser operation with relatively short codes. Thus, practical downlink rates of tens of Mb/s for each user can be obtained. However, multipath reflec- tions in diffuse channels cause strong multipath dispersion and, consequently, severe distortion. This distortion becomes even more severe in a multiuser environment, as the dispersed incoherent infrared radiation of all users aggregates together. To mitigate this distortion, we use a novel adaptive multilevel serial composite decision feedback and feedforward equalizer. We investigate the system's performance with the proposed equalizer, and compare it with the performance of the same system, both composite decision-feedback and feedforward Equalizers, and with a conven- tional decision-feedback equalizer (DFE). Our results show that the proposed scheme enables a high-data-rate multiaccess link and eliminates most of the multiuser distortion. Furthermore, it improves system performance in a multiaccess environment, as compared with the other composite Equalizers and DFE for the same complexity. We also compare other coding schemes, and show that Hadamard codes are on top of the other codes. Index Terms—Decision-feedback equalizer (DFE), decision feed- forward equalizer, indoor wireless communication, infrared (IR) communication, multiaccess communication, optical code-division multiple access (OCDMA).
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Multiuser diffuse indoor wireless infrared communication using equalized synchronous CDMA
IEEE Transactions on Communications, 2006Co-Authors: Uri N Griner, Shlomi ArnonAbstract:We propose an indoor wireless infrared downlink scheme for high-data-rate multiuser connectivity with diffuse channels. The scheme is based on synchronous code-division multiple access with unipolar Hadamard codes. The orthogonality of unipolar Hadamard codes enables multiuser operation with relatively short codes. Thus, practical downlink rates of tens of Mb/s for each user can be obtained. However, multipath reflections in diffuse channels cause strong multipath dispersion and, consequently, severe distortion. This distortion becomes even more severe in a multiuser environment, as the dispersed incoherent infrared radiation of all users aggregates together. To mitigate this distortion, we use a novel adaptive multilevel serial composite decision feedback and feedforward equalizer. We investigate the system's performance with the proposed equalizer, and compare it with the performance of the same system, both composite decision-feedback and feedforward Equalizers, and with a conventional decision-feedback equalizer (DFE). Our results show that the proposed scheme enables a high-data-rate multiaccess link and eliminates most of the multiuser distortion. Furthermore, it improves system performance in a multiaccess environment, as compared with the other composite Equalizers and DFE for the same complexity. We also compare other coding schemes, and show that Hadamard codes are on top of the other codes
Uri N Griner - One of the best experts on this subject based on the ideXlab platform.
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multiuser diffuse indoor wireless infrared communication using equalized
2006Co-Authors: Uri N Griner, Shlomi ArnonAbstract:We propose an indoor wireless infrared downlink scheme for high-data-rate multiuser connectivity with diffuse channels. The scheme is based on synchronous code-division multiple access with unipolar Hadamard codes. The orthogonality of unipolar Hadamard codes enables multiuser operation with relatively short codes. Thus, practical downlink rates of tens of Mb/s for each user can be obtained. However, multipath reflec- tions in diffuse channels cause strong multipath dispersion and, consequently, severe distortion. This distortion becomes even more severe in a multiuser environment, as the dispersed incoherent infrared radiation of all users aggregates together. To mitigate this distortion, we use a novel adaptive multilevel serial composite decision feedback and feedforward equalizer. We investigate the system's performance with the proposed equalizer, and compare it with the performance of the same system, both composite decision-feedback and feedforward Equalizers, and with a conven- tional decision-feedback equalizer (DFE). Our results show that the proposed scheme enables a high-data-rate multiaccess link and eliminates most of the multiuser distortion. Furthermore, it improves system performance in a multiaccess environment, as compared with the other composite Equalizers and DFE for the same complexity. We also compare other coding schemes, and show that Hadamard codes are on top of the other codes. Index Terms—Decision-feedback equalizer (DFE), decision feed- forward equalizer, indoor wireless communication, infrared (IR) communication, multiaccess communication, optical code-division multiple access (OCDMA).
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Multiuser diffuse indoor wireless infrared communication using equalized synchronous CDMA
IEEE Transactions on Communications, 2006Co-Authors: Uri N Griner, Shlomi ArnonAbstract:We propose an indoor wireless infrared downlink scheme for high-data-rate multiuser connectivity with diffuse channels. The scheme is based on synchronous code-division multiple access with unipolar Hadamard codes. The orthogonality of unipolar Hadamard codes enables multiuser operation with relatively short codes. Thus, practical downlink rates of tens of Mb/s for each user can be obtained. However, multipath reflections in diffuse channels cause strong multipath dispersion and, consequently, severe distortion. This distortion becomes even more severe in a multiuser environment, as the dispersed incoherent infrared radiation of all users aggregates together. To mitigate this distortion, we use a novel adaptive multilevel serial composite decision feedback and feedforward equalizer. We investigate the system's performance with the proposed equalizer, and compare it with the performance of the same system, both composite decision-feedback and feedforward Equalizers, and with a conventional decision-feedback equalizer (DFE). Our results show that the proposed scheme enables a high-data-rate multiaccess link and eliminates most of the multiuser distortion. Furthermore, it improves system performance in a multiaccess environment, as compared with the other composite Equalizers and DFE for the same complexity. We also compare other coding schemes, and show that Hadamard codes are on top of the other codes
