Study of ultracapacitors dynamic behaviour using impedance frequency analysis on a specific test bench

Lajnef, Walid; Vinassa, Jean-Michel; Briat, Olivier; Azzopardi, Stéphane; Zardini, Christian

doi:10.1109/isie.2004.1571922

Cited by 12 publications

(8 citation statements)

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“…Various supercapacitor equivalent models [17]- [20] have been developed. 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.…”

Section: Previous Workmentioning

confidence: 99%

“…In impedance spectroscopy, a small ac ripple superimposed with a dc bias voltage. But a difficulty that is faced here is that the capacitance of the supercapacitor under test is so high (140F) that the ac ripple has no effect and only parasitic values are From Figure 17, it can be observed that the Nyquist plot can be divided as three sections [20]- [21]. The vertical asymptote at low frequencies corresponds to capacitive and equivalent series resistive behavior.…”

Section: Equivalent Circuit Of Fuel Cellmentioning

confidence: 99%

“…Hence a single capacitor is not enough to model the supercapacitor; distributed resistors and capacitors is required along with a series inductor to account for the nonlinear charge/discharge process [18]- [20]. Table V gives the parameters of the equivalent model shown in Figure 16.…”

Section: Equivalent Circuit Of Fuel Cellmentioning

confidence: 99%

“…It can be found that the control to output transfer function of the converter when fuel cell is considered is given by (12). From the fuel cell equivalent circuit discussed in 2.2 its output impedance is given by (20). (20) By plotting the magnitudes of the converter input impedances and fuel cell output impedance (18)- (20) for the fuel cell parameters shown in Table IV and for a 350 W buck converter designed to operate in continuous conduction with a 20 mH inductance and 4400 mF output capacitance, the graph in Figure 29 is obtained.…”

Section: Transient State Stability Analysismentioning

confidence: 99%

“…From the fuel cell equivalent circuit discussed in 2.2 its output impedance is given by (20). (20) By plotting the magnitudes of the converter input impedances and fuel cell output impedance (18)- (20) for the fuel cell parameters shown in Table IV and for a 350 W buck converter designed to operate in continuous conduction with a 20 mH inductance and 4400 mF output capacitance, the graph in Figure 29 is obtained. It can be seen from Figure 29 that the magnitudes of the converter input impedance and the fuel cell output impedance are of comparable magnitudes.…”

Section: Transient State Stability Analysismentioning

confidence: 99%

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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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Section: Previous Workmentioning

confidence: 99%

Section: Equivalent Circuit Of Fuel Cellmentioning

confidence: 99%