262 research outputs found
Electrical Aging of the Insulation of Low Voltage Machines: Model definition and test with the Design of Experiments
No full textThe aim of this paper is to present a method for modeling
the lifespan of insulation materials in a partial discharge regime. Based on the design of experiments, it has many advantages: it reduces the number of time-consuming experiments, increases the accuracy of the results and allows lifespan modeling under various stress conditions including coupling effects between the factors. Accelerated aging tests are carried out to determine the lifespan of these materials. The resulting model presents an original relationship between the logarithm of the insulation lifespan and that of electrically applied stress and an exponential form of the temperature. Results show that the most influential factors can be identified according to their effects on the insulation lifespan. Moreover, the lifespan model validity is tested either with additional points which have not been used for modeling or through statistical tests. Finally, it is shown that fractional plans are not suitable to reduce the number of experiments. This application of the experimental design is best used during the initial phase, before the final drive has been built and any on-line diagnostic
Characterization of Acoustic Resonance in a High Pressure Sodium Lamp
No full textWith the last decades, the high pressure sodium (HPS) lamp has been supplied in high frequency in order to increase the efficacy of the lamp/ballast system. However, at some given frequencies, standing acoustic waves, namely acoustic resonance (AR), might develop in the burner and cause lamp luminous fluctuation, extinction and destruction in the most serious case. As we seek for a control method to detect and avoid the lamp AR some main characteristics of the acoustic resonances in a 150W HPS lamp are presented in this paper,. The first one is the characteristic of the lamp AR threshold power, the second one is the differences between forward and backward frequency scanning effects during lamp open loop operation. Thirdly, lamp AR behaviour in closed loop operation with an LCC half bridge inverter will be presented and leads to a new point of view and a change in the choice of the AR detection method. These characteristics allow us to further understand the AR and to better control the lamp
Multi phase system for metal disc induction heating: modelling and RMS current control
No full textThis paper presents a multi phase induction system modelling for a metal disc heating and further industrial applications such as hot strip mill. An original architecture, with three concentric inductors supplied by three resonant current inverters leads to a reduced element system, without any coupling transformers, phase loop, mobile screens or mobile magnetic cores as it could be found in classical solutions. A simulation model is built, based on simplified equivalent models of electric and thermal phenomena. It takes into account data extracted from Flux2D® finite element software, concerning the energy transfer between the inductor currents and the piece to be heated. It is implemented in a versatile software PSim, initially dedicated to power electronic. An optimization procedure calculates the optimal supply currents in the inverters in order to obtain a desired power density profile in the work piece. The paper deals with The simulated and experimental results are compared in open-loop and closed loop. The paper ends with a current control method which sets RMS inductor currents in continuous and digital conditions
IMprove the thermal models in order to take into acount radiation and conduction and the influence of the temperature on the parameter variations
No full textThis project has as objective to improve the thermal model of Majid Souley thesis based on
Multi-coil heating technology, specifically, understand what is the result of changing the value of the
coefficient of thermal convection from a constant value to an expression dependent from
temperature. It also aspires to obtain graphical results from a simplified model of two coils in the
area of magnetic and thermal results.
For obtaining these results, some programs as PSIM® and ANSYS® will be used. PSIM® uses
simulation to plot results. In order of doing these simulations, it uses equations that have to been
deduced before, so the first step will be to introduce thermal equations to the model. These
equations have been already written in Majid Souley thesis but some of them have been changed.
ANSYS® model has been created from zero and using some 2-D examples of the problem a 3-D model
has been made.
The results obtained shown that, in the case of PSIM® model, hav to be improved because of
there is a lack of information between the first point and the center of the disk, and resolving that
type of problem is out from this project knowledge. So, the results obtained have been distorted by
this lack of information, but without taking this into account, PSIM® model has better results with a
constant value of the coefficient of thermal convection.
With ANSYS®, promising results have been obtained in the case of magnetic flux density
across the metal. The results of the distribution of magnetic flux density corresponds with the
expected from theory but the distribution of temperature has slightly differences of what is
supposed to be. Also, some results about structural movements have been obtained, and they must
be deeper studied.
To conclude, there is not any reason to reject thermal model used in PSIM® program but,
solving this lack of information will verify if using a coefficient of thermal convection dependent from
temperature the model is better or not. On the other hand, with the results obtained, the model is
better with a constant value of the coefficient of thermal convection.
With ANSYS®, the solution given can be a support for future models, although that the
distribution of temperatures has to be improved, but with that model other interesting results can be
obtained, like interior stress of the metal as a result of the magnetic field.Outgoin
Hybridization of the autonomous heliostat power for the future solar power towers
No full text-Study of different types of hybrid models. -Hybrid Model selected PSIM. -Implementation of the hybrid model in PSIM. - ConclusionsOutgoin
IMprove the thermal models in order to take into acount radiation and conduction and the influence of the temperature on the parameter variations
No full textThis project has as objective to improve the thermal model of Majid Souley thesis based on
Multi-coil heating technology, specifically, understand what is the result of changing the value of the
coefficient of thermal convection from a constant value to an expression dependent from
temperature. It also aspires to obtain graphical results from a simplified model of two coils in the
area of magnetic and thermal results.
For obtaining these results, some programs as PSIM® and ANSYS® will be used. PSIM® uses
simulation to plot results. In order of doing these simulations, it uses equations that have to been
deduced before, so the first step will be to introduce thermal equations to the model. These
equations have been already written in Majid Souley thesis but some of them have been changed.
ANSYS® model has been created from zero and using some 2-D examples of the problem a 3-D model
has been made.
The results obtained shown that, in the case of PSIM® model, hav to be improved because of
there is a lack of information between the first point and the center of the disk, and resolving that
type of problem is out from this project knowledge. So, the results obtained have been distorted by
this lack of information, but without taking this into account, PSIM® model has better results with a
constant value of the coefficient of thermal convection.
With ANSYS®, promising results have been obtained in the case of magnetic flux density
across the metal. The results of the distribution of magnetic flux density corresponds with the
expected from theory but the distribution of temperature has slightly differences of what is
supposed to be. Also, some results about structural movements have been obtained, and they must
be deeper studied.
To conclude, there is not any reason to reject thermal model used in PSIM® program but,
solving this lack of information will verify if using a coefficient of thermal convection dependent from
temperature the model is better or not. On the other hand, with the results obtained, the model is
better with a constant value of the coefficient of thermal convection.
With ANSYS®, the solution given can be a support for future models, although that the
distribution of temperatures has to be improved, but with that model other interesting results can be
obtained, like interior stress of the metal as a result of the magnetic field.Outgoin
IMprove the thermal models in order to take into acount radiation and conduction and the influence of the temperature on the parameter variations
No full textThis project has as objective to improve the thermal model of Majid Souley thesis based on
Multi-coil heating technology, specifically, understand what is the result of changing the value of the
coefficient of thermal convection from a constant value to an expression dependent from
temperature. It also aspires to obtain graphical results from a simplified model of two coils in the
area of magnetic and thermal results.
For obtaining these results, some programs as PSIM® and ANSYS® will be used. PSIM® uses
simulation to plot results. In order of doing these simulations, it uses equations that have to been
deduced before, so the first step will be to introduce thermal equations to the model. These
equations have been already written in Majid Souley thesis but some of them have been changed.
ANSYS® model has been created from zero and using some 2-D examples of the problem a 3-D model
has been made.
The results obtained shown that, in the case of PSIM® model, hav to be improved because of
there is a lack of information between the first point and the center of the disk, and resolving that
type of problem is out from this project knowledge. So, the results obtained have been distorted by
this lack of information, but without taking this into account, PSIM® model has better results with a
constant value of the coefficient of thermal convection.
With ANSYS®, promising results have been obtained in the case of magnetic flux density
across the metal. The results of the distribution of magnetic flux density corresponds with the
expected from theory but the distribution of temperature has slightly differences of what is
supposed to be. Also, some results about structural movements have been obtained, and they must
be deeper studied.
To conclude, there is not any reason to reject thermal model used in PSIM® program but,
solving this lack of information will verify if using a coefficient of thermal convection dependent from
temperature the model is better or not. On the other hand, with the results obtained, the model is
better with a constant value of the coefficient of thermal convection.
With ANSYS®, the solution given can be a support for future models, although that the
distribution of temperatures has to be improved, but with that model other interesting results can be
obtained, like interior stress of the metal as a result of the magnetic field.Outgoin
Hybridization of the autonomous heliostat power for the future solar power towers
No full text-Study of different types of hybrid models. -Hybrid Model selected PSIM. -Implementation of the hybrid model in PSIM. - ConclusionsOutgoin
Hybridization of the autonomous heliostat power for the future solar power towers
No full text-Study of different types of hybrid models. -Hybrid Model selected PSIM. -Implementation of the hybrid model in PSIM. - ConclusionsOutgoin
Chasses de l'Algerie, et notes sur les arabes du sud.
No full textLetter to Madame de Maussion (?) from the author, 1869, tipped in.Mode of access: Internet
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