The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Denes Fodor - One of the best experts on this subject based on the ideXlab platform.
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Degradation Analysis of DC-Link Aluminium Electrolytic Capacitors Operating in PWM Power Converters
Advances in Electrical and Electronic Engineering, 2020Co-Authors: Krisztian Enisz, László Kovács, Denes Fodor, Gabor Kohlrusz, Richard MarschalkoAbstract:The most common failure mode of Aluminium Electrolytic Capacitor is the so-called wear out fault. It is caused by the high core temperature of the Capacitor. Therefore, life cycle calculations generally use temperature data to estimate degradation level. Core temperature-based life cycle calculations can consider different current loads on Capacitors. The calculation method uses scaling factors for different ripple current waveforms. However, it is not observed that temperature only is responsible for aging, but current waveform also influences the level of degradation. Therefore, sinusoidal and PWM-loaded Capacitor tests were performed under the same temperature conditions. The results show that the pore distribution of Aluminium anode foil has changed during the test. The pore diameter reduces and it leads to an increase in the ESR value and decrease in the capacitance, electrolyte amount and weight. Comparative results show that the PWM-loaded Capacitor is more degraded than the Capacitor loaded by sinusoidal test current.
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Aluminium Electrolytic Capacitor Model for Capacitor Materials Structure Transformation Analysis in PWM Applications
2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC), 2018Co-Authors: László Kovács, Gabor Kohlrusz, Krisztian Enisz, Denes FodorAbstract:The Electrolytic Capacitor is widely used in power electronics applications. These converters mainly operate with PWM (Pulse Width Modulation) which is commonly used circuit control technique currently. The widely known and generally used Capacitor models can not represent or model the exact behavior of the component in switch mode applications. Consequently, the physical structure of the Capacitor is not represented properly. A novel model has been introduced which represents precisely the physical structure of the Capacitor taking into account all structural elements. The electrical behavior of the novel model has been validated by circuit simulations. Utilizing the model, simulation results provided detailed information of component stress which helps to find an explanation to the effects of electrochemical processes in Capacitors.
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Influence of Can Flatness on Heat Dissipation of Aluminium Electrolytic Capacitor
Hungarian Journal of Industrial Chemistry, 2013Co-Authors: László Kovács, László Gál, Denes FodorAbstract:The lifetime of Aluminium Electrolytic Capacitors highly depends on their core temperature. Heat dissipation in general applications happens by the extended cathode, which is in contact with the inner side of the can. In the case of heat sink applications, the most important heat transfer phenomenon is the heat conduction through the bottom of the Aluminium can. The quantity of the dissipated heat is in direct proportion to the size of the heat transfer surface. The more dissipated heat may increase the lifetime of the Capacitor. Therefore, the flatness value of the can bottom is critical. This paper presents a flatness measurement method, which can successfully replace the equipment for a more complex and more expensive 3D measurement. It discusses an implementation of a measurement environment, where data acquisition and visualization are automated by a LabVIEW-based software. In addition, this study deals briefly with the influence of production processes on the flatness value of the Capacitor produced by leading manufacturers.
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Estimation of the Maximum Applicable Voltage Level of Aluminium Electrolytic Capacitors by Automated Spark-Detection Measurement
Hungarian Journal of Industrial Chemistry, 2011Co-Authors: Lehel István Kovács, Denes FodorAbstract:The paper deals with the presentation of a complete Measurement Automation System (MAS) implemented in an Aluminium Electrolytic Capacitor Development Laboratory at EPCOS Hungary. The main function of the MAS is to facilitate electrolyte and Capacitor research and development by automation of the related measurement tasks and to provide a powerful database system background for data retrieval and decision support. The presentation focuses on the architecture of the spark-detection measurement system and introduces a reliable estimation procedure for determining the maximum level of the voltage which can be applied to the Capacitor without damage. For the design engineers it is often impossible to determine the exact maximum voltage which will never be exceeded in the application. With the presented spark detection measurement a good estimation of the allowable maximum voltage can be given.
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Electrolyte Measurements Automation for Capacitor Research and Development
2006 12th International Power Electronics and Motion Control Conference, 2006Co-Authors: Denes Fodor, O. Klug, I. Balint, A. Horvath, A. RizAbstract:The paper deals with the presentation of a complete Measurement Automation System (MAS) implemented in an Aluminium Electrolytic Capacitor Development Laboratory at EPCOS Hungary. The main role of the MAS is to facilitate the electrolyte and Capacitor research and development, through the automation of the related measurement tasks, and to provide a powerful database system background for data retrieval and decision support. For the realization of the above requirements the National Instrument measurement and development tools were chosen as implementation and development platform. The presentation focuses on the architecture of the measurement system and presents the implementation process via a significant measurement ("Mixing (conductivity with single temperature)"), selected from the more then ten automated measurements. The results shows that with the introduction of the innovative MAS system in the Lab the research and development time for new electrolytes and Capacitors has been decreased considerably.
H. Uchi - One of the best experts on this subject based on the ideXlab platform.
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Modelling the capacitance of d.c. etched Aluminium Electrolytic Capacitor foil
Journal of Applied Electrochemistry, 2000Co-Authors: D. G. W. Goad, H. UchiAbstract:A model for the capacitance of anode foil used in Aluminium Electrolytic Capacitors is compared with experimental data for commercial foils from two different manufacturers. These foils are obtained by anodic electrochemical etching to produce a porous tunnel etched structure, followed by formation of a layer of dielectric Aluminium oxide in the pores. Data for the density and size of tunnels is obtained by sectioning the foil parallel to its surface with an ultramicrotome to several depths. In this paper the internal structure is modelled as a spatially random collection of hollow dielectric cylinders. Comparison of the measured capacitance with that calculated from the dimensional data and the model are in good agreement. The model predicts optimum values for tunnel size and density as a function of oxide thickness.
D. G. W. Goad - One of the best experts on this subject based on the ideXlab platform.
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Modelling the capacitance of d.c. etched Aluminium Electrolytic Capacitor foil
Journal of Applied Electrochemistry, 2000Co-Authors: D. G. W. Goad, H. UchiAbstract:A model for the capacitance of anode foil used in Aluminium Electrolytic Capacitors is compared with experimental data for commercial foils from two different manufacturers. These foils are obtained by anodic electrochemical etching to produce a porous tunnel etched structure, followed by formation of a layer of dielectric Aluminium oxide in the pores. Data for the density and size of tunnels is obtained by sectioning the foil parallel to its surface with an ultramicrotome to several depths. In this paper the internal structure is modelled as a spatially random collection of hollow dielectric cylinders. Comparison of the measured capacitance with that calculated from the dimensional data and the model are in good agreement. The model predicts optimum values for tunnel size and density as a function of oxide thickness.
László Kovács - One of the best experts on this subject based on the ideXlab platform.
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Degradation Analysis of DC-Link Aluminium Electrolytic Capacitors Operating in PWM Power Converters
Advances in Electrical and Electronic Engineering, 2020Co-Authors: Krisztian Enisz, László Kovács, Denes Fodor, Gabor Kohlrusz, Richard MarschalkoAbstract:The most common failure mode of Aluminium Electrolytic Capacitor is the so-called wear out fault. It is caused by the high core temperature of the Capacitor. Therefore, life cycle calculations generally use temperature data to estimate degradation level. Core temperature-based life cycle calculations can consider different current loads on Capacitors. The calculation method uses scaling factors for different ripple current waveforms. However, it is not observed that temperature only is responsible for aging, but current waveform also influences the level of degradation. Therefore, sinusoidal and PWM-loaded Capacitor tests were performed under the same temperature conditions. The results show that the pore distribution of Aluminium anode foil has changed during the test. The pore diameter reduces and it leads to an increase in the ESR value and decrease in the capacitance, electrolyte amount and weight. Comparative results show that the PWM-loaded Capacitor is more degraded than the Capacitor loaded by sinusoidal test current.
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Aluminium Electrolytic Capacitor Model for Capacitor Materials Structure Transformation Analysis in PWM Applications
2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC), 2018Co-Authors: László Kovács, Gabor Kohlrusz, Krisztian Enisz, Denes FodorAbstract:The Electrolytic Capacitor is widely used in power electronics applications. These converters mainly operate with PWM (Pulse Width Modulation) which is commonly used circuit control technique currently. The widely known and generally used Capacitor models can not represent or model the exact behavior of the component in switch mode applications. Consequently, the physical structure of the Capacitor is not represented properly. A novel model has been introduced which represents precisely the physical structure of the Capacitor taking into account all structural elements. The electrical behavior of the novel model has been validated by circuit simulations. Utilizing the model, simulation results provided detailed information of component stress which helps to find an explanation to the effects of electrochemical processes in Capacitors.
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Influence of Can Flatness on Heat Dissipation of Aluminium Electrolytic Capacitor
Hungarian Journal of Industrial Chemistry, 2013Co-Authors: László Kovács, László Gál, Denes FodorAbstract:The lifetime of Aluminium Electrolytic Capacitors highly depends on their core temperature. Heat dissipation in general applications happens by the extended cathode, which is in contact with the inner side of the can. In the case of heat sink applications, the most important heat transfer phenomenon is the heat conduction through the bottom of the Aluminium can. The quantity of the dissipated heat is in direct proportion to the size of the heat transfer surface. The more dissipated heat may increase the lifetime of the Capacitor. Therefore, the flatness value of the can bottom is critical. This paper presents a flatness measurement method, which can successfully replace the equipment for a more complex and more expensive 3D measurement. It discusses an implementation of a measurement environment, where data acquisition and visualization are automated by a LabVIEW-based software. In addition, this study deals briefly with the influence of production processes on the flatness value of the Capacitor produced by leading manufacturers.
Zongli Dou - One of the best experts on this subject based on the ideXlab platform.
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Low ESR Aluminium Electrolytic Capacitors for Medium to High Voltage Applications
2011Co-Authors: Alfonso Berduque, Juliet Martin, Zongli DouAbstract:Low ESR (Equivalent-Series-Resistance) Aluminium Electrolytic Capacitors for medium to high voltage applications have been developed, with a typical ESR reduction of up to 30%, in comparison with our current Aluminium Electrolytic Capacitor products. The effects on ESR have been considered by a combination of modelling and experimentation, evaluating the electrolyte, paper separators, cathode foils, anode foils and the number of tab connections. This evaluation indicated that the electrolyte and paper combination make a significant contribution to the ESR under the application conditions. In order to achieve the target ESR reduction, a new electrolyte of increased conductivity had to be developed. The new electrolyte, namely NE-400, with a working temperature range of –40 to 105˚C, is suitable for voltage applications up to 400 V at 85°C and 350 V at 105°C. Capacitor endurance tests at 400 V and 85˚C, showed that the NE-400 electrolyte improves the Capacitor performance significantly, when compared with the current CE-450 electrolyte. NE-400 results in low and stable ESR values over a testing period of 6000 hours. NE-400 was also compared to our current CE-350 electrolyte at 350 V and 105˚C, showing significant improvement in the Capacitor ESR and stability by using the new electrolyte. Suitable surge voltage capability and excellent characteristics at both low and high temperatures were also achieved.
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Electrochemical Studies for Aluminium Electrolytic Capacitor Applications: Corrosion Analysis of Aluminium in Ethylene Glycol-Based Electrolytes
2009Co-Authors: Alfonso Berduque, Zongli DouAbstract:The use of the Tafel plot electrochemical technique has been presented as a corrosion test method for Aluminium Electrolytic Capacitor applications. This technique has been used to study the electrochemical corrosion of Aluminium in ethylene glycol solvent-based electrolytes. These electrolytes consist of organic and inorganic acids, bases and conductive salts dissolved in ethylene glycol, and some of them also contain corrosion inhibitors and other additives. The Tafel plot corrosion current, icorr, was measured and used to characterise all these electrolytes, showing significant differences between electrolytes (different icorr values), due to their different chemical compositions. In addition, the Tafel plot technique was also used to study different corrosion inhibitors in one of the test electrolytes. From the Tafel plot results, it was found that the optimum concentrations of these inhibitors in the electrolyte were ca. 0.15–0.25 % ammonium hypophosphite; 0.75–1 % phosphoric acid; 0.1–0.2 % ammonium dihydrogen phosphate; and 0.4– 0.6 % dibutyl phosphate. Therefore, this corrosion technique can be employed to investigate the Aluminium corrosion caused by different electrolytes and to determine the optimum corrosion inhibitor and its concentration for each particular electrolyte.
