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Nasser Kutkut

Bio: Nasser Kutkut is an academic researcher from University of Central Florida. The author has contributed to research in topics: Solar micro-inverter & Inverter. The author has an hindex of 31, co-authored 68 publications receiving 3936 citations. Previous affiliations of Nasser Kutkut include University of Wisconsin-Madison & Wisconsin Alumni Research Foundation.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications is presented, compared and scrutinized in scope of the size of decoupled capacitor, efficiency, and control complexity.
Abstract: The reliability of the microinverter is a very important feature that will determine the reliability of the ac-module photovoltaic (PV) system. Recently, many topologies and techniques have been proposed to improve its reliability. This paper presents a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications. These power decoupling techniques are categorized into three groups in terms of the decoupling capacitor locations: 1) PV-side decoupling; 2) dc-link decoupling; and 3) ac-side decoupling. Various techniques and topologies are presented, compared, and scrutinized in scope of the size of decoupling capacitor, efficiency, and control complexity. Also, a systematic performance comparison is presented for potential power decoupling topologies and techniques.

458 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a new charge equalization technique for a series string of battery cells, which utilizes a simple isolated DC-to-DC power converter with a capacitive output filter along with a multiwinding transformer.
Abstract: Charge equalization for series-connected battery strings has important ramifications on battery life. It enhances the uniformity of the battery cells and, hence, improves the life of the battery as a whole. A new charge equalization technique for a series string of battery cells has been recently proposed by the authors. The basic technique utilizes a simple isolated DC-to-DC power converter with a capacitive output filter along with a multiwinding transformer. The possibility of integrating the trickle charge function with the charge equalization function is potentially very attractive, as it can lead to an efficient and low-cost implementation.

279 citations

Journal ArticleDOI
TL;DR: This paper presents a comprehensive review of multiport converters for integrating solar energy with energy storage systems, featuring the advantages and disadvantages of the various topologies leading to suggestions for the direction of future research.
Abstract: This paper presents a comprehensive review of multiport converters for integrating solar energy with energy storage systems. With recent development of a battery as a viable energy storage device, the solar energy is transforming into a more reliable and steady source of power. Research and development of multiport converters is instrumental in enabling this transformation in an efficient manner. The high efficiency of conversion in comparatively smaller footprint makes a multiport converter very attractive in this application. Most of the recently reported multiport converter topologies are discussed here. A breakdown of isolated and nonisolated topologies is presented along with the comparison of converter architectures and features such as operating conditions, device count, efficiency, etc. Each group of multiport converters is subdivided into different smaller groups based on their architecture. Detailed specifications are presented for important topologies. Finally, a performance comparison is carried out featuring the advantages and disadvantages of the various topologies leading to suggestions for the direction of future research.

237 citations

Proceedings ArticleDOI
06 Oct 1996
TL;DR: In this article, the authors present, discuss and evaluate the different techniques proposed to achieve individual cell equalization for series battery stacks, and evaluate different techniques for series connected battery stacks is not as straightforward.
Abstract: Secondary battery life can be dramatically improved if the charging process can be regulated to prevent gassing and overcharging. This can be achieved by controlling the battery charging rate especially near the end of the charge cycle. Different charging algorithms have been devised to achieve this goal for individual battery modules. However, extending these algorithms to series connected battery stacks is not as straightforward. Normal differences in cell chemistries and temperature gradients along a battery stack can lead to large nonuniformities in cell charge levels. Maintenance of cells at an equalized charge level is critical for enhancing battery life. Different systems and schemes have been proposed to attain this goal. This paper presents, discusses and evaluates the different techniques proposed to achieve individual cell equalization for series battery stacks.

225 citations

Journal ArticleDOI
TL;DR: In this paper, a flyback converter is used to separate the decoupling capacitor from the PV Module, which allows for a high voltage and voltage ripples across its terminals.
Abstract: This paper presents a new microinverter topology that is intended for single-phase grid-connected PV systems. The proposed microinverter topology is based on a flyback converter, where an extra switch is added to separate the decoupling capacitor from the PV Module, which allows for a high voltage and voltage ripples across its terminals. This results in reducing the power decoupling required capacitance. In this manner, long life-time low power density film capacitors can be used instead of life-time limited high power density electrolytic capacitors, resulting in remarkable increase of microinverter's lifespan. The main advantages of the proposed topology are summarized as: 1) eliminating the double-frequency power ripple using a small film capacitor; 2) using long lifetime film capacitors, which will improve the reliability of the inverter; and 3) requiring no additional circuitry to manage the transformer leakage energy. A 100-W microinverter prototype was built to verify the proposed topology. Experimental results show that the proposed topology and its control scheme can realize the power decoupling, while maintaining very good conversion efficiency numbers.

208 citations


Cited by
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Journal ArticleDOI
Languang Lu1, Xuebing Han1, Jianqiu Li1, Jianfeng Hua, Minggao Ouyang1 
TL;DR: In this article, a brief introduction to the composition of the battery management system (BMS) and its key issues such as battery cell voltage measurement, battery states estimation, battery uniformity and equalization, battery fault diagnosis and so on, is given.

3,650 citations

01 Nov 2000
TL;DR: In this paper, the authors compared the power density characteristics of ultracapacitors and batteries with respect to the same charge/discharge efficiency, and showed that the battery can achieve energy densities of 10 Wh/kg or higher with a power density of 1.2 kW/kg.
Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

2,437 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrid vehicles and classify them into off-board and on-board types with unidirectional or bidirectional power flow.
Abstract: This paper reviews the current status and implementation of battery chargers, charging power levels, and infrastructure for plug-in electric vehicles and hybrids. Charger systems are categorized into off-board and on-board types with unidirectional or bidirectional power flow. Unidirectional charging limits hardware requirements and simplifies interconnection issues. Bidirectional charging supports battery energy injection back to the grid. Typical on-board chargers restrict power because of weight, space, and cost constraints. They can be integrated with the electric drive to avoid these problems. The availability of charging infrastructure reduces on-board energy storage requirements and costs. On-board charger systems can be conductive or inductive. An off-board charger can be designed for high charging rates and is less constrained by size and weight. Level 1 (convenience), Level 2 (primary), and Level 3 (fast) power levels are discussed. Future aspects such as roadbed charging are presented. Various power level chargers and infrastructure configurations are presented, compared, and evaluated based on amount of power, charging time and location, cost, equipment, and other factors.

2,327 citations

Journal ArticleDOI
TL;DR: In this article, power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems.
Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.

2,296 citations

Journal Article
TL;DR: In this article, power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems.
Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.

2,076 citations