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Robust control of parallel dc-dc buck converters by combining integral-variable-structure control and multiple-sliding surface control schemes
- IEEE Trans. Power Electron
, 2000
"... Abstract—We develop a robust controller for parallel dc–dc buck converters by combining the concepts of integral-vari-able-structure and multiple-sliding-surface control. The advan-tages of the scheme are its simplicity in design, good dynamic response, robustness, ability to nullify the bus-voltage ..."
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Cited by 13 (2 self)
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Abstract—We develop a robust controller for parallel dc–dc buck converters by combining the concepts of integral-vari-able-structure and multiple-sliding-surface control. The advan-tages of the scheme are its simplicity in design, good dynamic response, robustness, ability to nullify the bus-voltage error and the error between the load currents of the converter modules under steady-state conditions, and ability to reduce the impact of very high-frequency dynamics due to parasitics on the closed-loop system. We describe a method for determining the region of existence and stability of the sliding manifolds for such parallel converters. The results show good steady-state and dynamic responses. Index Terms—Closed-loop system, integral-variable-structure, load currents, multiple-sliding-surface control, parallel converters, I.
A novel droop method for converter parallel operation
- IEEE Trans. Power Electron
, 2002
"... Abstract—For the converter parallel operation, the current sharing between modules is important for the reliability of the system. Among several current sharing schemes, the droop method needs no interconnection between modules, which implies true redundancy. But the droop method has poor voltage re ..."
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Cited by 12 (0 self)
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Abstract—For the converter parallel operation, the current sharing between modules is important for the reliability of the system. Among several current sharing schemes, the droop method needs no interconnection between modules, which implies true redundancy. But the droop method has poor voltage regulation and poor current sharing characteristics. In this paper, a novel droop method is proposed for the converter parallel operation, which adaptively controls the reference voltage of each module. This greatly improves the output voltage regula-tion and the current sharing of the conventional droop method. The analysis of the proposed method and design procedure are pro-vided and experimental results verify the excellent performance of the proposed method. Index Terms—Converter parallel operation, current sharing, droop method, sample and hold. NOMENCLATURE Output voltage of module #. Output voltage set-point of module #. Output current of module #. Conventional droop gain. Nominal output voltage. Output voltage set-point accuracy. Maximum output voltage variation. Rated output current of one module. Maximum output current sharing error. Peak output current of module #. Output current breakpoint set value. Droop gain of the proposed method. Output voltage offset adjusting gain. Output voltage sensing gain. I.
Droop-Control-Based State-of-Charge Balancing Method for Charging and Discharging Process in Autonomous DC Microgrids
"... Early version, also known as pre-print ..."
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SoC-Based Droop Method for Distributed Energy Storage in DC Microgrid Applications
, 2012
"... Document Version Early version, also known as pre-print Link to publication from Aalborg University Citation for published version (APA): ..."
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Document Version Early version, also known as pre-print Link to publication from Aalborg University Citation for published version (APA):
On the Effects of Voltage Loop in Paralleled Converters Under Master-Slave Current Sharing
"... Abstract — This paper studies the effects of the presence of voltage loops in parallel connected buck switching converters under master-slave current sharing scheme. The system employs a typical proportional-integral (PI) controller for regulation. Comparisons are made for the cases where the slave ..."
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Abstract — This paper studies the effects of the presence of voltage loops in parallel connected buck switching converters under master-slave current sharing scheme. The system employs a typical proportional-integral (PI) controller for regulation. Comparisons are made for the cases where the slave modules are controlled with and without a voltage loop. Generally, we find that the voltage loop in the slave is helpful in widening the stability range though it is theoretically redundant for the purpose of controlling the output voltage in the small-signal sense. Such a loop provides stable current reference for the slave modules. Effectively, each slave module is under current-mode control by virtue of the current sharing loop, making it a current source. Simulation results under different control configurations are presented to demonstrate the phenomenon. I.
DC–DC Converters
"... Abstract—This paper describes a classification of paralleling schemes for dc–dc converters from a circuit theoretic viewpoint. The purpose is to provide a systematic classification of the types of parallel converters that can clearly identify all possible structures and control configurations, allow ..."
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Abstract—This paper describes a classification of paralleling schemes for dc–dc converters from a circuit theoretic viewpoint. The purpose is to provide a systematic classification of the types of parallel converters that can clearly identify all possible structures and control configurations, allowing simple and direct comparison of the characteristics and limitations of different paralleling schemes. In the proposed classification, converters are modeled as current sources or voltage sources, and their connection possibilities, as constrained by Kirchhoff’s laws, are categorized systematically into three basic types. Moreover, control arrangements are classified according to the presence of current sharing and voltage-regulation loops. Computer simulations are presented to illustrate the characteristics of the various paralleling schemes. Index Terms—Control methods, current-sharing schemes, dc–dc converters, parallel connected converters, topology. I.
Study of Stability Regions in Parallel Connected Boost Converters
"... Abstract—This paper describes the coexisting attractors of parallel connected boost switching converters under a master-slave current sharing scheme. We present the basins of attraction of desired and undesired attractors, which provide design information on the conditions for hot-swap operations. T ..."
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Abstract—This paper describes the coexisting attractors of parallel connected boost switching converters under a master-slave current sharing scheme. We present the basins of attraction of desired and undesired attractors, which provide design information on the conditions for hot-swap operations. The system employs a typical proportional-integral (PI) controller for regulation. It is shown that the system will converge to different attractors for different initial conditions with the same control parameters. Simulation results are given to illustrate the phenomenon. This study is relevant to practical design. Specifically, we show that the stability regions obtained from linear methods (i.e., considering only local stability) can be over-optimistic as the global stability regions are found to be more restrictive in the parameter space. I.
Average Modeling, Analysis And Simulation Of Current Shared Dc-Dc Converters
"... A practical, 'user-friendly' methodology is developed to study the behavior of current-shared converters. It applies average modeling, analysis and simulation to examine the static conditions and small-signal stability of converters that operate in Average Current Sharing (ACS) mode. Simpl ..."
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A practical, 'user-friendly' methodology is developed to study the behavior of current-shared converters. It applies average modeling, analysis and simulation to examine the static conditions and small-signal stability of converters that operate in Average Current Sharing (ACS) mode. Simple expressions for stability criterion were developed and applied to assess the influence of the number of paralleled modules on the stability and dynamics of the converters system. I. INTRODUCTION Paralleling of DC-DC converters has many desirable features: increased reliability, expandability and on-site repair when hot plug-in capability is incorporated. However, the analysis and design of parallel converters are far from being simple due to the fact that they are no longer of the singleinput single-output type [1-6]. For increased reliability, paralleled converters require a Current Sharing (CS) mechanism to ensure distribution of currents and stresses between the modules. Unfortunately, the CS co...
Dynamic System Modelling of Multiloop Operation for Paralleled DC/DC Converters
"... In this paper a system of parallel-connected DC/DC converters including all interconnection resistances is modelled and analysed. H − optimal control is used in order to design a robust controller that guarantees robust stability and robust performance in spite of different uncertainties. The modell ..."
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In this paper a system of parallel-connected DC/DC converters including all interconnection resistances is modelled and analysed. H − optimal control is used in order to design a robust controller that guarantees robust stability and robust performance in spite of different uncertainties. The modelling, analysis and control design procedures presented are verified by a design example. 1.
