Characterization methods and modelling of ultracapacitors for use as peak power sources

Lajnef, Walid; Vinassa, Jean-Michel; Briat, Olivier; Azzopardi, Stéphane; Woirgard, Eric

doi:10.1016/j.jpowsour.2007.02.049

Cited by 129 publications

(50 citation statements)

References 9 publications

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“…Constant power tests are commonly used for the characterization of electric storage devices and generators. For an ultracapacitor, the common experimental procedure is discharging the ultracapacitor with constant power between two voltage limits of V rated and 0.5 V rated in order to measure the specific energy that any particular ultracapacitor can supply as function of discharge power [47]. It can be seen from Fig.…”

Section: Battery and Ultracapacitor Model Development And Verificationmentioning

confidence: 99%

Dynamic performance of an in-rack proton exchange membrane fuel cell battery system to power servers

Brouwer

James

et al. 2017

International Journal of Hydrogen Energy

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a b s t r a c tTo improve the reliability and the energy efficiency of data centers, as well as to reduce infrastructure costs and environmental impacts, we experimentally evaluated in-rack powering of servers with a hybrid 12 kW Proton Exchange Membrane Fuel Cell (PEMFC) and battery system. The steady state and the transient performance of the PEMFC and battery in response to dynamic AC loads and real server loads have been evaluated and characterized. The PEMFC system responds quickly and reproducibly to load changes directly from the server rack. Peak efficiency of 55.2% in a single server rack can be achieved. The effect of fuel cell coolant temperature on the hybrid system transient behavior is also captured and evaluated. The observed PEMFC transient responses obtained from the experiments were used to design the size of the energy storage component for the hybrid system. Simulations and analysis of various types of energy storage devices for the hybrid system were carried out. To provide power to meet the most significant transient demand, energy storage capacity greater than 0.3 kWh is required for all battery types, while only 0.053 kWh capacity is required for the ultracapacitor. During charging, the ultracapacitor uses the shortest amount of time to recover to the original SOC, while the charging duration for the lead acid battery is twice as long as that of the ultracapacitor.

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Section: Battery and Ultracapacitor Model Development And Verificationmentioning

confidence: 99%

Dynamic performance of an in-rack proton exchange membrane fuel cell battery system to power servers

Brouwer

James

et al. 2017

International Journal of Hydrogen Energy

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“…Numerous authors have constructed models to predict the electrical behaviour of EDLCs that can broadly be categorised as either physical models [23][24][25] or equivalent circuit models, [16,[26][27][28][29][30][31] . Although the physical models provide us with more information about the phenomena occurring within the cell, these models remain relatively immature, and to date, no model has provided validated results over a complex drive cycle.…”

Section: Model Structuresmentioning

confidence: 99%

“…Although the physical models provide us with more information about the phenomena occurring within the cell, these models remain relatively immature, and to date, no model has provided validated results over a complex drive cycle. Lajnef et al, [29], developed a generic equivalent circuit model for an EDLC as shown in Figure 3a, and demonstrated that it reproduced EDLC behaviour reasonably well over long time periods whilst at a constant temperature. Devillers et al, [31], compares the accuracy of multiple electrical models over a period of 700 seconds at different temperatures, and confirms the findings of Lajnef et al For this study, good reproduction of electrical behaviour over complex drive cycles is necessary, therefore an equivalent circuit model is favoured over a physical model.…”

Section: Model Structuresmentioning

confidence: 99%

“…Each RC branch has a time constant that relates to the rearrangement of ions; charge re-distribution is a non-linear process, hence the greater the number of RC branches utilised, the lower this discrepancy will be, at the trade-off of greater complexity. A detailed description of the correlation between electrical circuit elements and the physical processes occurring within the cell during operation has been complete by numerous authors, [15,21,33]. The following works study the effect of transmission line length, [15], and the the number of RC branches, [34].…”

Section: Model Structuresmentioning

confidence: 99%

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Electrochemical double layer capacitor electro-thermal modelling

Sarwar

Marinescu

Green

et al. 2016

Journal of Energy Storage

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Highlights An electro-thermal model is created which is valid from (-)40 → (+)60℃  A peudo-3D thermal model is developed to determine spatial temperature variation  Electrical equivalent circuit model retains physical meaning  Differing rates of heat generation are defined for the individual cell constituents  The temperature gradient between the core of the cell and surface is defined AbstractAn electro-thermal model is generated to predict the internal temperature of an Electrochemical Double-Layer Capacitor (EDLC) undergoing high current charging/discharging. The model is capable of predicting the electrical and thermal behaviour of a cell over a wide range of operating conditions. Spiral symmetry is used to reduce the heat generation and transfer model from 3D to a pseudo-3D, which runs faster without losing fidelity. Unlike existing models, each element in the developed model retains physical meaning and the electrical model is coupled with a high-fidelity thermal model including material geometries, thermal properties and air gaps. Unequal entropy is calculated using first principles, included in the model and compared to experimental data, and shown to be valid. More entropic heat is generated at the positive electrode than the negative in a typical EDLC, and there is little spatial variation of heat generation rate within the jelly-roll. The heat-transfer model predicts temperature variations within a cell; this study examines these variations for multiple conditions. Whilst undergoing high current charging (2 seconds, 400A, 650F cell), a temperature gradient in excess of 3.5℃ can be generated between the positive terminal and the jelly-roll. The time dependent spatial temperature distribution within a cell is explored.

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“…In The effect on the dynamics of the DC-DC converter due to the internal impedance of the fuel cell has not been studied so far. However analytical tools exist that can facilitate this analysis [21]. The use of a fuel cell as a power source for DC-DC converters can be treated in a similar fashion as when a filter is connected between the power source and a DC-DC converter.…”

Section: Previous Workmentioning

confidence: 99%

Fuel Cell Based Battery-Less UPS System

Chellappan

Todorovic

Enjeti

2008

2008 IEEE Industry Applications Society Annual Meeting

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With the increased usage of electrical equipment for various applications, the demand for quality power apart from continuous power availability has increased and hence requires the development of appropriate power conditioning system. A major factor during development of these systems is the requirement that they remain environment-friendly. This cannot be realized using the conventional systems as they use batteries and/or engine generators. Among various viable technologies, fuel cells have emerged as one of the most promising sources for both portable and stationary applications.In this thesis, a new battery less UPS system configuration powered by fuel cell is discussed. The proposed topology utilizes a standard offline UPS module and the battery is replaced by a supercapacitor. The system operation is such that the supercapacitor bank is sized to support startup and load transients and steady state power is supplied by the fuel cell. Further, the fuel cell runs continuously to supply 10% power in steady state. In case of power outage, it is shown that the startup time for fuel cell is reduced and the supercapacitor bank supplies power till the fuel cell ramps up from supplying iv 10% load to 100% load. A detailed design example is presented for a 200W/350VA 1-phase UPS system to meet the requirements of a critical load. The equivalent circuit and hence the terminal behavior of the fuel cell and the supercapacitor are considered in the analysis and design of the system for a stable operation over a wide range. The steady state and transient state analysis were used for stability verification.Hence, from the tests such as step load changes and response time measurements, the non-linear model of supercapacitor was verified. Temperature rise and fuel consumption data were measured and the advantages of having a hybrid source (supercapacitor in parallel with fuel cell) over just a standalone fuel cell source were shown. Finally, the transfer times for the proposed UPS system and the battery based UPS system were measured and were found to be satisfactory. Overall, the proposed system was found to satisfy the required performance specifications.

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Characterization methods and modelling of ultracapacitors for use as peak power sources

Cited by 129 publications

References 9 publications

Dynamic performance of an in-rack proton exchange membrane fuel cell battery system to power servers

Dynamic performance of an in-rack proton exchange membrane fuel cell battery system to power servers

Electrochemical double layer capacitor electro-thermal modelling

Fuel Cell Based Battery-Less UPS System

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