The Experts below are selected from a list of 24342 Experts worldwide ranked by ideXlab platform
Ym Lai - One of the best experts on this subject based on the ideXlab platform.
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Output Impedance shaping of bidirectional dab dc dc converter using double proportional integral feedback for near ripple free dc bus voltage regulation in renewable energy systems
IEEE Transactions on Power Electronics, 2016Co-Authors: Lingling Cao, Kh Loo, Ym LaiAbstract:This paper investigates the design and implementation of virtual-Output-Impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc–dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second Output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-Output-Impedance shaping (proportional, derivative, integral) are discussed and the closed-loop Output-Impedance characteristics due to each of them are analyzed in detail and with their Thevenin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's Output Impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-Output-Impedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dual-active-bridge dc–dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.
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Output-Impedance shaping of bidirectional DAB DC-DC converter using double-proportional-integral feedback for near-ripple-free DC bus voltage regulation in renewable energy systems
Institute of Electrical and Electronics Engineers, 2016Co-Authors: Cao L, Kh Loo, Ym LaiAbstract:This paper investigates the design and implementation of virtual-Output-Impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc-dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second Output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-Output-Impedance shaping (proportional, derivative, integral) are discussed and the closed-loop Output-Impedance characteristics due to each of them are analyzed in detail and with their The'venin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's Output Impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-OutputImpedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dualactive-bridge dc-dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.Department of Electronic and Information Engineerin
Lingling Cao - One of the best experts on this subject based on the ideXlab platform.
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Output Impedance shaping of bidirectional dab dc dc converter using double proportional integral feedback for near ripple free dc bus voltage regulation in renewable energy systems
IEEE Transactions on Power Electronics, 2016Co-Authors: Lingling Cao, Kh Loo, Ym LaiAbstract:This paper investigates the design and implementation of virtual-Output-Impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc–dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second Output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-Output-Impedance shaping (proportional, derivative, integral) are discussed and the closed-loop Output-Impedance characteristics due to each of them are analyzed in detail and with their Thevenin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's Output Impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-Output-Impedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dual-active-bridge dc–dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.
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systematic derivation of a family of Output Impedance shaping methods for power converters a case study using fuel cell battery powered single phase inverter system
IEEE Transactions on Power Electronics, 2015Co-Authors: Lingling Cao, Kh Loo, Yuk Ming LaiAbstract:For power converters used in renewable energy systems, Output-Impedance design has become an important design consideration for minimizing the impacts of low-frequency harmonic current on the lifetime of ripple-sensitive energy sources such as fuel cells and photovoltaic cells. In the literature, various methods are proposed to tackle this design issue but they are frequently treated in isolation from each other and specific to the systems being discussed. In this paper, a systematic derivation of four basic modes of Output-Impedance shaping method is presented. These basic modes can be directly inferred from the Mason's gain formula and other methods are in essence derivatives or combinations of these basic modes. By using a fuel-cell-battery-powered single-phase inverter as an implementation example, their characteristics are discussed thoroughly and their performances in shaping converter's Output Impedance are evaluated experimentally.
Kh Loo - One of the best experts on this subject based on the ideXlab platform.
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Output Impedance shaping of bidirectional dab dc dc converter using double proportional integral feedback for near ripple free dc bus voltage regulation in renewable energy systems
IEEE Transactions on Power Electronics, 2016Co-Authors: Lingling Cao, Kh Loo, Ym LaiAbstract:This paper investigates the design and implementation of virtual-Output-Impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc–dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second Output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-Output-Impedance shaping (proportional, derivative, integral) are discussed and the closed-loop Output-Impedance characteristics due to each of them are analyzed in detail and with their Thevenin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's Output Impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-Output-Impedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dual-active-bridge dc–dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.
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Output-Impedance shaping of bidirectional DAB DC-DC converter using double-proportional-integral feedback for near-ripple-free DC bus voltage regulation in renewable energy systems
Institute of Electrical and Electronics Engineers, 2016Co-Authors: Cao L, Kh Loo, Ym LaiAbstract:This paper investigates the design and implementation of virtual-Output-Impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc-dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second Output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-Output-Impedance shaping (proportional, derivative, integral) are discussed and the closed-loop Output-Impedance characteristics due to each of them are analyzed in detail and with their The'venin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's Output Impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-OutputImpedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dualactive-bridge dc-dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.Department of Electronic and Information Engineerin
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systematic derivation of a family of Output Impedance shaping methods for power converters a case study using fuel cell battery powered single phase inverter system
IEEE Transactions on Power Electronics, 2015Co-Authors: Lingling Cao, Kh Loo, Yuk Ming LaiAbstract:For power converters used in renewable energy systems, Output-Impedance design has become an important design consideration for minimizing the impacts of low-frequency harmonic current on the lifetime of ripple-sensitive energy sources such as fuel cells and photovoltaic cells. In the literature, various methods are proposed to tackle this design issue but they are frequently treated in isolation from each other and specific to the systems being discussed. In this paper, a systematic derivation of four basic modes of Output-Impedance shaping method is presented. These basic modes can be directly inferred from the Mason's gain formula and other methods are in essence derivatives or combinations of these basic modes. By using a fuel-cell-battery-powered single-phase inverter as an implementation example, their characteristics are discussed thoroughly and their performances in shaping converter's Output Impedance are evaluated experimentally.
Fang Zhuo - One of the best experts on this subject based on the ideXlab platform.
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Beat Frequency Oscillation Analysis for Power Electronic Converters in DC Nanogrid Based on Crossed Frequency Output Impedance Matrix Model
IEEE Transactions on Power Electronics, 2018Co-Authors: Dushan Boroyevich, Rolando Burgos, Fang Chen, Fang ZhuoAbstract:The interaction of power electronic converters in a microgrid can introduce system instability and power quality issues. Existing investigations focus on interactions either in low-frequency regions, such as the constant power load, or in very high-frequency regions like electromagnetic interference. However, interactions of power converters around their switching frequency range are not included. In fact, the interaction of dc-dc converters with different switching frequencies can introduce beat frequency oscillation in certain cases. Since additional frequency component (beat frequency) is generated, traditional Impedance concept is no longer the tool for beat frequency oscillation analysis and new models need to be developed. In this paper, a crossed frequency Output Impedance matrix model is proposed to describe the terminal characteristics of a dc-dc converter around its switching frequency range. A high-frequency equivalent circuit model for the converter is then developed to predict the beat frequency oscillation in parallel and cascaded systems, which results from the interaction of power converters with different switching frequencies. Finally, design guidelines are proposed to avoid potential beat frequency oscillation in a dc nanogrid. Experimental results for both parallel and cascaded systems validate the accuracy and effectiveness of the proposed prediction method and design guidelines.
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a matrix based multifrequency Output Impedance model for beat frequency oscillation analysis in distributed power systems
IEEE Journal of Emerging and Selected Topics in Power Electronics, 2016Co-Authors: Xiaolong Yue, Fang Zhuo, Shuhao Yang, Yunqing PeiAbstract:Power electronic converters are single input multiple Output (SIMO) systems in frequency domain. In distributed power system (DPS), one converter’s switching frequency ripples are another converter’s perturbations, and beat frequency components are generated due to their SIMO characteristics. As the control loops of power converters always take high gains in low-frequency regions if the beat frequency components are relatively low, they may be magnified and presented as oscillations, which will introduce system instability. This paper proposes a matrix-based multifrequency Output Impedance model to describe the SIMO characteristics of power converters and to analyze the stability of DPS. The buck converter is specifically illustrated as demonstration. The proposed model indicates that the variation of switching frequency, as well as those traditionally discussed parameters of control loops and passive components, could also change Output Impedance characteristics and introduce system instability. In DPS, the beat frequency oscillation that traditional models fail to explain could be accurately predicted by the proposed model. In addition, based on the proposed model, the switching frequencies for power converters can be optimized to improve the stability of power electronic-based systems. Simulation and experimental results validate the accuracy and the effectiveness of the proposed method.
J. Miret - One of the best experts on this subject based on the ideXlab platform.
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designing vrm hysteretic controllers for optimal transient response
IEEE Transactions on Industrial Electronics, 2007Co-Authors: Miguel Castilla, J Matas, L.g. De Vicuna, Josep M Guerrero, J. MiretAbstract:This paper presents a design methodology for voltage hysteretic regulators powering digital integrated circuits with low voltage, high current, and high slew rate current transients. The design approach optimizes the transient response during large consumption changes by imposing constant closed-loop Output Impedance. This paper also suggests a novel compensator network for the adaptive voltage positioning feedback loop, which leads to a robust transient response performance against load disturbances. The application of the design methodology to the proposed hysteretic controller provides the suitable control parameter values for optimal transient response. Simulation and experimental results validate the theoretical predictions for the proposed controller, particularly the constant Output Impedance operation and the robust transient response performance
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droop control method for the parallel operation of online uninterruptible power systems using resistive Output Impedance
Applied Power Electronics Conference, 2006Co-Authors: J.m. Guerrero, N Berbel, J Matas, L.g. De Vicuna, J. Miret, Miguel CastillaAbstract:In this paper, a novel wireless load sharing controller for parallel connected online UPS inverters is proposed. As opposed to the conventional droop method, the proposed method achieves stable steady-state frequency and phase and an good dynamic response is obtained. A virtual Output Impedance is proposed in order to reduce its line Impedance impact and to properly share nonlinear loads. Experimental results are presented from two 6-kVA UPS inverters controlled by DSP boards, showing the feasibility of the proposed approach.
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Output Impedance design of parallel connected ups inverters with wireless load sharing control
IEEE Transactions on Industrial Electronics, 2005Co-Authors: Josep M Guerrero, Miguel Castilla, J Matas, L.g. De Vicuna, J. MiretAbstract:This paper deals with the design of the Output Impedance of uninterruptible power system (UPS) inverters with parallel-connection capability. In order to avoid the need for any communication among modules, the power-sharing control loops are based on the P/Q droop method. Since in these systems the power-sharing accuracy is highly sensitive to the inverters Output Impedance, novel control loops to achieve both stable Output Impedance and proper power balance are proposed. In this sense, a novel wireless controller is designed by using three nested loops: 1) the inner loop is performed by using feedback linearization control techniques, providing a good quality Output voltage waveform; 2) the intermediate loop enforces the Output Impedance of the inverter, achieving good harmonic power sharing while maintaining low Output voltage total harmonic distortion; and 3) the outer loop calculates the Output active and reactive powers and adjusts the Output Impedance value and the Output voltage frequency during the load transients, obtaining excellent power sharing without deviations in either the frequency or the amplitude of the Output voltage. Simulation and experimental results are reported from a parallel-connected UPS system sharing linear and nonlinear loads.
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Steady-state invariant frequency and amplitude droop control using adaptive Output Impedance for parallel-connected UPS inverters
Twentieth Annual IEEE Applied Power Electronics Conference and Exposition 2005. APEC 2005., 2005Co-Authors: J.m. Guerrero, J Matas, L.g. De Vicuna, J. Miret, J. CruzAbstract:In this paper, a novel wireless load-sharing controller for parallel connected UPS inverters is proposed. As opposed to the conventional droop method, the proposed method achieves stable steady-state frequency and amplitude. The paper explorers the Output Impedance of the UPS inverters, and adaptive virtual Output Impedance is proposed in order to reduce its line Impedance impact. Experimental results are presented from two 6 kVA UPS inverters controlled by TMS320LF2407A DSP boards, showing the feasibility of the proposed approach
