COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 1992
The torque harmonics generated by asynchronous machine slotting are essentially linked to air‐gap... more The torque harmonics generated by asynchronous machine slotting are essentially linked to air‐gap permeance variations due to the rotor rotation. These variations lead to machine inductance coefficient fluctuations which are at the begining of torque harmonics. So the problem consists to determine the permeance variation law as well as for its mean value that for its “harmonics”. The aim of this study is to end at analytical expressions which allow to calculate the torque harmonic magnitudes whatever the considered machine. In consequence the numerical methods (e.g. finite element method) are not appropriated because their implementation considering the rotation will be too long and, in the other hand, they only permit, from calculus results, to estimate this permeance variation law. To resolve this problem by analytical way this law must be characterized by a simple expression. That leads the authors to translate the complex phenomena, linked to the field line repartition in the slotting, by simple laws applied to a fictitious slot model. After presenting the selected model to characterize the slots, the authors introduce the angle per unit permeance notion which permits to make clear the air gap permeance variation law in function of rotor rotation. The experimental verifications which relate to inductance coefficients and torque harmonics permit to validate these permeance variation law and in consequence the selected fictitious slot model. The evolution of these quantities in function of the magnetic field magnitude inside the machine permits the authors to propose a fictitious slot model evolution law which can take the saturation into account.
6th International Conference on Power Electronics and Variable Speed Drives, 1996
ABSTRACT The detailed analytic study of the induction machine, taking the slotting effects into a... more ABSTRACT The detailed analytic study of the induction machine, taking the slotting effects into account, allows the influence of the rotor speed on the harmonic content of the stator currents to be shown. This result has also been confirmed by tests realised on wound and squirrel cage rotor machines. The magnitudes of the speed dependant current spectrum lines are very low because they are functions of the small e.m.f. induced in the stator, which are tied to the stator and rotor slot geometry, but also of the impedance of the electric circuit constituted of the stator phase reactance and the grid one. To achieve the realisation of the speed sensor the spectrum line magnitudes have first to be amplified. Then a narrow band switched capacitor analog active filter, in which central frequency is controlled by a phase locked loop, is used. This device produces a logic signal with a frequency which is an exact multiple of the rotor speed. A logic counter is employed to display the result.
2012 XXth International Conference on Electrical Machines, 2012
ABSTRACT Vibrations and noise in transformers core have two main origins: the Maxwell's f... more ABSTRACT Vibrations and noise in transformers core have two main origins: the Maxwell's forces, located in the corners, and the magnetostriction inside magnetic steel. In this paper, these two phenomena are differentiated and analyzed and analyzed using a test bench, which allows comparing the vibrations of two different annular structures. In the first case only the magnetostriction occurs, whereas the second case is submitted to both the magnetostriction and the Maxwell's forces.
2007 IEEE International Electric Machines & Drives Conference, 2007
ABSTRACT Increasing the power delivery requires to optimize high power generators thanks to numer... more ABSTRACT Increasing the power delivery requires to optimize high power generators thanks to numerical tools as finite element applications. In this way, this paper presents a new concept called retro-design. It has been naturally introduced by the difficulties to determine the inner dimensions of high power machines, installed from many years, and for which plans are not always available. It concerns especially turbo-generators of thermal nuclear power stations. Consequently, in order to make easy the improvement of the generator performances with reliability without dismounting them for a long time, this paper presents an original procedure to find - a posteriori - the inner dimensions of the stator armature starting from a restricted initial data set as the rating plate. Such a determination do not use only a classical design method ; it requires to be coupled with a data base, even if this latter is restricted. The paper presents the procedure and the choices to make in order to find the best design parameters according to the power or the installation date of the generator. A retro-design example is given with a 1485 MW turbogenerator.
IEMDC 2001. IEEE International Electric Machines and Drives Conference (Cat. No.01EX485), 2001
ABSTRACT This paper presents several methods which allow characterisation of the order, the rank ... more ABSTRACT This paper presents several methods which allow characterisation of the order, the rank and the magnitude of three-phase harmonic systems generated by PWM inverter switching. In a second part, the authors describe an active magnetic noise reduction which controls the harmonic currents due to the switching in order to generate forces. These last are controlled to act in opposition with the forces due to the slots
Electric Machines and Drives IEEE International Conference, 2001
This paper analyses the contribution of the harmonic flux density in the total iron losses of an ... more This paper analyses the contribution of the harmonic flux density in the total iron losses of an induction machine. After presenting the modelling of these losses, simple experimental tests are used which show that the effects are significant in the stator core as well as in the rotor core. Finally, a procedure allows definition of the contribution of each harmonic
2005 European Conference on Power Electronics and Applications, 2005
The aim of this paper is to show quantitatively how external radial magnetic field spectral lines... more The aim of this paper is to show quantitatively how external radial magnetic field spectral lines vary when a short-circuit fault appears on induction machine stator winding. The sensitivity of the spectral lines to the fault is estimated by changing the ratio of the shorted turn current comparatively to the supply current. For a given position of the used sensor, the sensitivity of particular spectral lines is also analysed depending on the location of the fault in the stator winding
Computer Engineering in Applied Electromagnetism, 2005
The paper describes the application of the general load line method to a magnetic circuit problem... more The paper describes the application of the general load line method to a magnetic circuit problem with series and parallel branches of uniform cross sections consisting of the same homogeneous ferromagnetic core material, and presents a comparison with finite element analysis results.
2007 International Aegean Conference on Electrical Machines and Power Electronics, 2007
This paper deals with the impact of rotor bar materials such as aluminum or copper on domestic he... more This paper deals with the impact of rotor bar materials such as aluminum or copper on domestic heating circulator pumps . First, we describe the test bench used to do experiments. Secondly, we present the interest of changing rotor bar materials in pumps system drives and finally, we present experimental results.
2013 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), 2013
ABSTRACT The stray flux in the vicinity of an electrical machine is inherent to its running. It i... more ABSTRACT The stray flux in the vicinity of an electrical machine is inherent to its running. It is tied to the magnetic state of the machine and therefore can be affected by the presence of a fault in the machine. Accurate modeling of the external magnetic field is quite complicated and simple models are required in order to analyze the effect of an internal fault on the stray flux. This paper displays the possibilities offers by the stray flux for fault detection. A simple model of the external magnetic field is presented and a study in healthy and faulty conditions is developed. Two kind of fault in induction machine are considered: stator inter-turn short-circuit and rotor broken bar. Experimental results are in agreement with the theory, they highlight the differentiation between the radial flux and the axial flux.
Proceedings of the International Conference on ELECTRONICS, COMPUTERS and ARTIFICIAL INTELLIGENCE - ECAI-2013, 2013
ABSTRACT The paper deals with the modeling of a three-phase self-excited induction generator and ... more ABSTRACT The paper deals with the modeling of a three-phase self-excited induction generator and its steady state analysis using space vector formalism. The behavior of an induction generator working in autonomous mode and which supply an inductive resistive load is presented using a numerical model developed in Matlab-simulink. The startup phenomenon and the problematic which appear for this working mode are presented and discussed leaning on the simulated results obtained from various studied cases. Computed characteristics have been verified experimentally in laboratory using three-phase squirrel-cage induction machine. Significant agreement between experimentally and simulated results obtained with proposed numerical model is shown in the paper.
2013 International Conference on Control, Decision and Information Technologies (CoDIT), 2013
ABSTRACT This paper presents a comparative study for two frequency control strategy applied to a ... more ABSTRACT This paper presents a comparative study for two frequency control strategy applied to a self excited induction generator equipping a wind turbine in remote site. This study was conducted through the analysis of the frequency in the steady state and transient case using a developed induction generator numerical model. The simulation results obtained by numerical model are validated using an experimental test bench. For frequency control a fuzzy logic controller is presented in the paper and validated using Matlab-Simulink environment. The simulation results obtained by fuzzy controller are compared with those provided by a specific law obtained from analytical study of induction generator.
COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, 1992
The torque harmonics generated by asynchronous machine slotting are essentially linked to air‐gap... more The torque harmonics generated by asynchronous machine slotting are essentially linked to air‐gap permeance variations due to the rotor rotation. These variations lead to machine inductance coefficient fluctuations which are at the begining of torque harmonics. So the problem consists to determine the permeance variation law as well as for its mean value that for its “harmonics”. The aim of this study is to end at analytical expressions which allow to calculate the torque harmonic magnitudes whatever the considered machine. In consequence the numerical methods (e.g. finite element method) are not appropriated because their implementation considering the rotation will be too long and, in the other hand, they only permit, from calculus results, to estimate this permeance variation law. To resolve this problem by analytical way this law must be characterized by a simple expression. That leads the authors to translate the complex phenomena, linked to the field line repartition in the slotting, by simple laws applied to a fictitious slot model. After presenting the selected model to characterize the slots, the authors introduce the angle per unit permeance notion which permits to make clear the air gap permeance variation law in function of rotor rotation. The experimental verifications which relate to inductance coefficients and torque harmonics permit to validate these permeance variation law and in consequence the selected fictitious slot model. The evolution of these quantities in function of the magnetic field magnitude inside the machine permits the authors to propose a fictitious slot model evolution law which can take the saturation into account.
6th International Conference on Power Electronics and Variable Speed Drives, 1996
ABSTRACT The detailed analytic study of the induction machine, taking the slotting effects into a... more ABSTRACT The detailed analytic study of the induction machine, taking the slotting effects into account, allows the influence of the rotor speed on the harmonic content of the stator currents to be shown. This result has also been confirmed by tests realised on wound and squirrel cage rotor machines. The magnitudes of the speed dependant current spectrum lines are very low because they are functions of the small e.m.f. induced in the stator, which are tied to the stator and rotor slot geometry, but also of the impedance of the electric circuit constituted of the stator phase reactance and the grid one. To achieve the realisation of the speed sensor the spectrum line magnitudes have first to be amplified. Then a narrow band switched capacitor analog active filter, in which central frequency is controlled by a phase locked loop, is used. This device produces a logic signal with a frequency which is an exact multiple of the rotor speed. A logic counter is employed to display the result.
2012 XXth International Conference on Electrical Machines, 2012
ABSTRACT Vibrations and noise in transformers core have two main origins: the Maxwell's f... more ABSTRACT Vibrations and noise in transformers core have two main origins: the Maxwell's forces, located in the corners, and the magnetostriction inside magnetic steel. In this paper, these two phenomena are differentiated and analyzed and analyzed using a test bench, which allows comparing the vibrations of two different annular structures. In the first case only the magnetostriction occurs, whereas the second case is submitted to both the magnetostriction and the Maxwell's forces.
2007 IEEE International Electric Machines & Drives Conference, 2007
ABSTRACT Increasing the power delivery requires to optimize high power generators thanks to numer... more ABSTRACT Increasing the power delivery requires to optimize high power generators thanks to numerical tools as finite element applications. In this way, this paper presents a new concept called retro-design. It has been naturally introduced by the difficulties to determine the inner dimensions of high power machines, installed from many years, and for which plans are not always available. It concerns especially turbo-generators of thermal nuclear power stations. Consequently, in order to make easy the improvement of the generator performances with reliability without dismounting them for a long time, this paper presents an original procedure to find - a posteriori - the inner dimensions of the stator armature starting from a restricted initial data set as the rating plate. Such a determination do not use only a classical design method ; it requires to be coupled with a data base, even if this latter is restricted. The paper presents the procedure and the choices to make in order to find the best design parameters according to the power or the installation date of the generator. A retro-design example is given with a 1485 MW turbogenerator.
IEMDC 2001. IEEE International Electric Machines and Drives Conference (Cat. No.01EX485), 2001
ABSTRACT This paper presents several methods which allow characterisation of the order, the rank ... more ABSTRACT This paper presents several methods which allow characterisation of the order, the rank and the magnitude of three-phase harmonic systems generated by PWM inverter switching. In a second part, the authors describe an active magnetic noise reduction which controls the harmonic currents due to the switching in order to generate forces. These last are controlled to act in opposition with the forces due to the slots
Electric Machines and Drives IEEE International Conference, 2001
This paper analyses the contribution of the harmonic flux density in the total iron losses of an ... more This paper analyses the contribution of the harmonic flux density in the total iron losses of an induction machine. After presenting the modelling of these losses, simple experimental tests are used which show that the effects are significant in the stator core as well as in the rotor core. Finally, a procedure allows definition of the contribution of each harmonic
2005 European Conference on Power Electronics and Applications, 2005
The aim of this paper is to show quantitatively how external radial magnetic field spectral lines... more The aim of this paper is to show quantitatively how external radial magnetic field spectral lines vary when a short-circuit fault appears on induction machine stator winding. The sensitivity of the spectral lines to the fault is estimated by changing the ratio of the shorted turn current comparatively to the supply current. For a given position of the used sensor, the sensitivity of particular spectral lines is also analysed depending on the location of the fault in the stator winding
Computer Engineering in Applied Electromagnetism, 2005
The paper describes the application of the general load line method to a magnetic circuit problem... more The paper describes the application of the general load line method to a magnetic circuit problem with series and parallel branches of uniform cross sections consisting of the same homogeneous ferromagnetic core material, and presents a comparison with finite element analysis results.
2007 International Aegean Conference on Electrical Machines and Power Electronics, 2007
This paper deals with the impact of rotor bar materials such as aluminum or copper on domestic he... more This paper deals with the impact of rotor bar materials such as aluminum or copper on domestic heating circulator pumps . First, we describe the test bench used to do experiments. Secondly, we present the interest of changing rotor bar materials in pumps system drives and finally, we present experimental results.
2013 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD), 2013
ABSTRACT The stray flux in the vicinity of an electrical machine is inherent to its running. It i... more ABSTRACT The stray flux in the vicinity of an electrical machine is inherent to its running. It is tied to the magnetic state of the machine and therefore can be affected by the presence of a fault in the machine. Accurate modeling of the external magnetic field is quite complicated and simple models are required in order to analyze the effect of an internal fault on the stray flux. This paper displays the possibilities offers by the stray flux for fault detection. A simple model of the external magnetic field is presented and a study in healthy and faulty conditions is developed. Two kind of fault in induction machine are considered: stator inter-turn short-circuit and rotor broken bar. Experimental results are in agreement with the theory, they highlight the differentiation between the radial flux and the axial flux.
Proceedings of the International Conference on ELECTRONICS, COMPUTERS and ARTIFICIAL INTELLIGENCE - ECAI-2013, 2013
ABSTRACT The paper deals with the modeling of a three-phase self-excited induction generator and ... more ABSTRACT The paper deals with the modeling of a three-phase self-excited induction generator and its steady state analysis using space vector formalism. The behavior of an induction generator working in autonomous mode and which supply an inductive resistive load is presented using a numerical model developed in Matlab-simulink. The startup phenomenon and the problematic which appear for this working mode are presented and discussed leaning on the simulated results obtained from various studied cases. Computed characteristics have been verified experimentally in laboratory using three-phase squirrel-cage induction machine. Significant agreement between experimentally and simulated results obtained with proposed numerical model is shown in the paper.
2013 International Conference on Control, Decision and Information Technologies (CoDIT), 2013
ABSTRACT This paper presents a comparative study for two frequency control strategy applied to a ... more ABSTRACT This paper presents a comparative study for two frequency control strategy applied to a self excited induction generator equipping a wind turbine in remote site. This study was conducted through the analysis of the frequency in the steady state and transient case using a developed induction generator numerical model. The simulation results obtained by numerical model are validated using an experimental test bench. For frequency control a fuzzy logic controller is presented in the paper and validated using Matlab-Simulink environment. The simulation results obtained by fuzzy controller are compared with those provided by a specific law obtained from analytical study of induction generator.
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