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    Wyświetlanie 1-12 z 12
    Tytuł:
    Development of a technique for inductive measurement of laser-induced magnetization dynamics in thin films
    Autorzy:
    Ilit’, Tomáš
    Valko, Pavol
    Držík, Milan
    Ušáková, Marianna
    Šoka, Martin
    Marton, Marian
    Behúl, Miroslav
    Vojs, Marian
    Powiązania:
    https://bibliotekanauki.pl/articles/220843.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    laser-induced demagnetization
    pulsed inductive microwave magnetometry
    ultrafast demagnetization detection
    Opis:
    We present the development of a technique for studying laser-induced magnetization dynamics, based on inductive measurement. The technique could provide a simple tool for studying laser-induced demagnetization in thin films and associated processes, such as Gilbert damping and magnetization precession. It was successfully tested using a nanosecond laser and NiZn ferrite samples and - after further development - itis expected to be useful for observation of ultra-fast demagnetization. The combination of optical excitation and inductive measurement enables to study laser-induced magnetization dynamics in both thin and several micrometre thick films and might be the key to a new principle of ultrafast broadband UV-IR pulse detection.
    Źródło:
    Metrology and Measurement Systems; 2019, 26, 3; 531-540
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Current Signals in a Partially Demagnetized Vector Controlled Interior Permanent Magnet Generator
    Autorzy:
    Quintal-Palomo, Roberto Eduardo
    Powiązania:
    https://bibliotekanauki.pl/articles/1193712.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    IPM
    PMSG
    co-simulation
    DFOC
    demagnetization
    Opis:
    This manuscript analyzes the operation of an interior permanent magnet (IPM) machine working as a permanent magnet synchronous generator (PMSG). The partial demagnetization operation is analyzed. To obtain more accurate voltages and currents of the machine, finite element analysis (FEA) is used in co-simulation with the full converter and the converter’s control algorithm. Direct field oriented control (DFOC) shows robustness by maintaining the speed even with a 25% demagnetized PMSG. Also, an analysis of the rotating reference frame DQ signals is done to asses demagnetization.
    Źródło:
    Power Electronics and Drives; 2019, 4, 39; 177-188
    2451-0262
    2543-4292
    Pojawia się w:
    Power Electronics and Drives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetization dependent demagnetization characteristic of rare-earth permanent magnets
    Autorzy:
    Bavendiek, Gregor
    Müller, Fabian
    Sabirov, Jamshid
    Hameyer, Kay
    Powiązania:
    https://bibliotekanauki.pl/articles/140527.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    demagnetization
    magnetic hysteresis
    magnetization processes
    permanent magnets
    Opis:
    Accurate demagnetization modelling is mandatory for a reliable design of rare- earth permanent magnet applications, such as e.g. synchronous machines. The magnetization of rare-earth permanent magnets requires high magnetizing fields. For technical reasons, it is not always possible to completely and homogeneously achieve the required field strength during a pulse magnetization, due to stray fields or eddy currents. Not sufficiently magnetized magnets lose remanence as well as coercivity and the demagnetization characteristic becomes strongly nonlinear. It is state of the art to treat demagnetization curves as linear. This paper presents an approach to model the nonlinear demagnetization in dependence on the magnetization field strength. Measurements of magnetization dependent demagnetization characteristics of rare-earth permanent magnets are compared to an analytical model description. The physical meaning of the model parameters and the influence on them by incomplete magnetization are discussed for different rare-earth permanent magnet materials. Basically, the analytic function is able to map the occurring magnetization dependent demagnetization behavior. However, if the magnetization is incomplete, the model parameters have a strong nonlinear behavior and can only be partially attributed to physical effects. As a benefit the model can represent nonlinear demagnetization using a few parameters only. The original analytical model is from literature but has been adapted for the incomplete magnetization. The discussed effect is not sufficiently accurate modelled in literature. The sparse data in literature has been supplemented with additional pulsed-field magnetometer measurements.
    Źródło:
    Archives of Electrical Engineering; 2019, 68, 1; 33-45
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of rotor’s cage resistance on demagnetization process in the line start permanent magnet synchronous motor
    Autorzy:
    Zawilak, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/141077.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    demagnetization
    falling out of step
    permanent magnets
    synchronous motor
    Opis:
    This paper deals with the finite element analysis of the demagnetization process of the line start permanent magnet synchronous motor. Special attention has been paid to demagnetization risk assessment after resynchronization during a short-term supply power outage. The current and torque waveforms have been determined assuming the difference depending initial rotor position angle. It has been demonstrated that the highest demagnetization risk occurs when resynchronization (motor reclosing) is performed when induced electromotive forces are in anti-phase to the supply voltage waveforms. The effect of cage winding resistance on the risk of demagnetization is examined and discussed.
    Źródło:
    Archives of Electrical Engineering; 2020, 69, 2; 249-258
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance comparison of double stator permanent magnet machines
    Autorzy:
    Awah, Chukwuemeka Chijioke
    Powiązania:
    https://bibliotekanauki.pl/articles/2172793.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    demagnetization
    double stator
    induced voltage
    losses
    power and torque
    Opis:
    The electromagnetic and output performance characteristics of three (3) different types of double stator permanent magnet machines are quantitatively compared and presented in this study, in order to determine the most promising machine topology amongst the considered machine types, for potential practical applications(s). Two-dimensional (2D) and three-dimensional (3D) finite element analysis (FEA) methods are deployed in the computation of the performance metrics using ANSYS-MAXWELL software. The compared machines in this work are designated as: Machine 1, Machine 2 and Machine 3, respectively. The investigated machines have varying structural arrangements and two separate excitation sources. Machine 1 has its magnets situated in the outer stator with corresponding armature windings on both inner and outer stators. The magnets of Machine 2 are located in its inner stator while it has armature windings on both inner and outer stator parts. More so, Machine 3 is equipped with magnets in its inner and outer stators, though without armature windings on the inner stator section. The considered performance metrics include: inducedelectromotive force (induced-EMF), torque, power, demagnetization, losses and efficiency. The results show that the investigated Machine 3 has higher induced-EMF value and more sinusoidal electromotive force waveform than the other compared machines. Consequently, Machine 3 also has larger electromagnetic torque and power. Moreover, Machine 1 has the best flux-weakening potential, obtained from both the ratio of its maximum speed to base speed and the flux-weakening factor ( kp).
    Źródło:
    Archives of Electrical Engineering; 2022, 71, 4; 829--850
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measures to reduce the residual field and field gradient inside a magnetically shielded room by a factor of more than 10
    Autorzy:
    Voigt, J.
    Knappe-Grüneberg, S.
    Schnabel, A.
    Körber, R.
    Burghoff, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/220358.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    magnetic shielding
    magnetic shielded room
    msr
    residual field
    residual field gradient
    degaussing
    demagnetization
    Opis:
    Very low residual magnetic field and field gradients are essential for a number of high resolution fundamental physical experiments and for further improvement of very sensitive magnetic measurement devices. The scope ranges from spin precession experiments, e.g. with 3He or neutrons, to biomagnetic measurements, like magnetoencephalograms, and to low field MR spectroscopy. One method of reducing environmental magnetic noise is to use a magnetically shielded room (MSR). Here, measures are demonstrated to improve residual field and field gradient inside a common MSR by a factor of more than 10 by a specific degaussing procedure, material selection of prefabricated parts and active shielding. The process is independent of the shielding factor and works also properly for heavily shielded rooms.
    Źródło:
    Metrology and Measurement Systems; 2013, 20, 2; 237-248
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sensitivity Limits and Functional Characteristics of Fluxgate Sensors with Rod-Shaped Magnetic Cores
    Granice czułości i charakterystyki funkcjonalne czujników fluxgate z rdzeniami magnetycznymi w kształcie prętów
    Autorzy:
    Kopala, Dominika
    Ostaszewska-Liżewska, Anna
    Szewczyk, Roman
    Powiązania:
    https://bibliotekanauki.pl/articles/2090887.pdf
    Data publikacji:
    2022
    Wydawca:
    Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
    Tematy:
    fluxgate sensors
    demagnetization coefficient
    magnetic permeability
    czujniki fluxgate
    współczynnik demagnetyzacji
    przenikalność magnetyczna
    Opis:
    Highly sensitive fluxgate magnetic field sensors with rod-shaped cores are widely used for non-destructive testing as well as for industrial applications. However, in case of both Foerster and Vacquier (two-core sensors configurations), fluxgate sensors sensitivity is directly connected with the relative magnetic permeability of the sensor’s core. It should be highlighted that the magnetic permeability of rod-shaped magnetic cores is driven mainly by the demagnetization factor determined by its slenderness (aspect ratio). The paper presents the analyses of sensitivity limits of fluxgate sensors with rod-shaped cores. On the base of estimations of demagnetization factor specific for fluxgate sensors, it is shown that in case of rod-shaped cores, the sensor’s sensitivity is connected with the shape of the core rather than its relative magnetic permeability. This conclusion is essential during the development and optimization of functional characteristics of fluxgate sensors.
    Bardzo czułe sensory pola magnetycznego typu fluxgate z rdzeniami w kształcie prętów są szeroko stosowane w badaniach nieniszczących, jak również w zastosowaniach przemysłowych. Jednak zarówno w przypadku czujnika w konfiguracji Foerster’a, jak i Vacquier’a (obie konfiguracje dotyczą sensorów dwurdzeniowych) ich czułość jest bezpośrednio związana ze względną przenikalnością magnetyczną rdzeni. Należy podkreślić, że o przenikalności magnetycznej prętowych rdzeni magnetycznych decyduje przede wszystkim współczynnik rozmagnesowania określony przez jego smukłość (proporcje). W artykule przedstawiono analizę granic czułości sensorów typu fluxgate z rdzeniami prętowymi. Na podstawie oszacowań współczynnika rozmagnesowania charakterystycznego dla czujników typu fluxgate wykazano, że w przypadku rdzeni prętowych czułość sensora związana jest raczej z kształtem rdzenia niż z jego względną przenikalnością magnetyczną. Wniosek ten jest szczególnie ważny podczas opracowywania i optymalizacji charakterystyk funkcjonalnych czujników fluxgate.
    Źródło:
    Pomiary Automatyka Robotyka; 2022, 26, 2; 29--33
    1427-9126
    Pojawia się w:
    Pomiary Automatyka Robotyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Introduction to the Special Section on Intelligent Fault Monitoring and Fault–Tolerant Control in Power Electronics, Drives and Renewable Energy Systems
    Autorzy:
    Malinowski, Mariusz
    Levi, Emil
    Orlowska-Kowalska, Teresa
    Powiązania:
    https://bibliotekanauki.pl/articles/1193706.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    electrical drives
    permanent magnet machine
    induction motors
    sensor fault
    winding fault
    demagnetization fault
    neural networks
    observers
    Opis:
    This article constitutes an introductory part of the special section on Intelligent Fault Monitoring and Fault-Tolerant Control in Power Electronics, Drives and Renewable Energy Systems. In the current issue of the journal, the first part of this section is published. Accepted articles are focussed mainly on the sensor-fault diagnosis methods for T-type inverter-fed dual- three phase PMSM drives, partial demagnetization, faults of the permanent magnet synchronous generator (PMSG) and online open phase fault detection (FD) in the sensorless five-phase induction motor drive implemented with an inverter output LC filter and third harmonic injection. Also, neural networks (NN) application in the detection of stator and rotor electrical faults of induction motors has been proposed in one of the papers, and the observer-based FD concept for unknown systems using input–output measurements was applied to a brushless direct current motor drive with unknown parameters.
    Źródło:
    Power Electronics and Drives; 2019, 4, 39; 163-165
    2451-0262
    2543-4292
    Pojawia się w:
    Power Electronics and Drives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimized design of a high-power-density PM-assisted synchronous reluctance machine with ferrite magnets for electric vehicles
    Autorzy:
    Liu, X.
    Li, Y.
    Liu, Z.
    Ling, T.
    Luo, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/140849.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    permanent magnet (PM)-assisted synchronous reluctance machine
    ferrite magnet
    demagnetization
    mechanical strength
    torque ripple
    finite element analysis
    Opis:
    This paper proposes a permanent magnet (PM)-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rareearth PM synchronous motors employed in Toyota Prius 2010. A suitable rotor structure for high torque density and high power density is discussed with respect to the demagnetization of ferrite magnets, mechanical strength and torque ripple. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2-D finite element analysis (FEA). The analysis results show that a high power density and high efficiency of PMASynRM are obtained by using ferrite magnets.
    Źródło:
    Archives of Electrical Engineering; 2017, 66, 2; 279-293
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Masking of ferromagnetic ellipsoidal shell in Earth’s magnetic field
    Autorzy:
    Jakubiuk, K.
    Wołoszyn, M.
    Zimny, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/97594.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
    Tematy:
    mathematical models of magnetic field
    magnetization of ferromagnetic object
    masking of ferromagnetic object
    windings for demagnetization of the ship
    Opis:
    A ferromagnetic object, located in the Earth’s magnetic field, changes the distribution of that field. By measuring such disturbances it is possible to detect the object and destroy it. To conceal the object, a special winding is placed inside its ferromagnetic shell, which function is to eliminate the disturbances in the distribution of the Earth’s magnetic field. A thin walled ellipsoidal shell made of ferromagnetic material are examined as the object model. Coils are placed inside the shell and their function is to generate a magnetic field, which eliminates the effect the shell makes on the distribution of the Earth’s magnetic field in the surrounding area. Such a procedure is called magnetic masking and the winding used for this purpose is called the masking winding. The possibility of building the masking windings for the ferromagnetic ellipsoidal shell, situated in a magnetic field transverse in relation to its major axis, is also examined. Masking of a thin-walled ellipsoidal ferromagnetic object located in the longitudinal magnetic field is described in the article [1]. Investigating the possibility of masking of objects in a transverse magnetic field presented in this article will allow for a comprehensive assessment of a possibility of masking thin walled ferromagnetic objects of elongated ellipsoidal shape. The solution of Maxwell’s equations, which describe the magnetic field distribution caused by the ferromagnetic shell presence in the Earth’s magnetic field, are applied. Furthermore, the ability of selecting coils, which fully eliminate the perturbations of the magnetic field outside the shell are proven.
    Źródło:
    Computer Applications in Electrical Engineering; 2013, 11; 92-99
    1508-4248
    Pojawia się w:
    Computer Applications in Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wyznaczanie prądów granicznych dla maszyn synchronicznych z magnesami trwałymi umieszczonymi powierzchniowo
    Determination of limiting currents synchronous machines with surface mounted permanent magnets
    Autorzy:
    Pawluk, K.
    Sobczyk, T. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/320330.pdf
    Data publikacji:
    2006
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    maszyny z magnesami trwałymi
    efekt demagnetyzacji
    graniczne wartości prądów
    model całkowo-brzegowy
    permanent magnet synchronous machines
    demagnetization effect
    limiting currents
    boundary integral approach
    Opis:
    Ocena zagrożenia utraty własności magnetycznych przez magnesy trwałe w maszynach synchronicznych jest szczególnie ważna w stanach dynamicznych, przy stosunkowo znacznych wartościach prądów. Istnieje potrzeba wyznaczenia granicznych wartości prądów, przy których nie wystąpi jeszcze zagrożenie demagnetyzacji w żadnej części magnesów trwałych. W pracy przedstawiono sposób wyznaczania strefy bezpiecznej pracy maszyn synchronicznych z magnesami umieszczonymi powierzchniowo na wirniku, na podstawie bardzo uproszczonych analiz pola w obszarze magnesów trwałych. Pokazano także, że rozkład pola magnetycznego w maszynie może być efektywnie obliczany metodą całek brzegowych, co może stanowić istotne uzupełnienie metodyki obliczeń projektowych.
    A risk of loss the magnetic feature of permanent magnets in synchronous machines should be evaluated. It is very important at dynamic state that is characterized by relatively important armature currents. It is need to determine the limiting currents for which the demagnetization does not occur at any part of magnet body. A method of delimiting the special safety zone is presented in the paper. The synchronous machines with permanent magnets being fixed externally upon a rotor yoke are concerned. The first attempt is performed on basis of rather simple one-directional field analysis. It is also shown that it may be improved by the boundary-integral approach to determine the magnetic field within an air-gap as well as in the magnet pieces.
    Źródło:
    Elektrotechnika i Elektronika; 2006, 25, 2; 187-191
    1640-7202
    Pojawia się w:
    Elektrotechnika i Elektronika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ekologiczne chłodziarki magnetyczne
    Ecological magnetic refrigerators
    Autorzy:
    Sulima, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/159969.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Elektrotechniki
    Tematy:
    chłodzenie magnetyczne
    materiały magnetokaloryczne
    magnesy trwałe
    analiza polowa 2D
    analiza polowa 3D
    magnetic refrigeration
    magnetocaloric materials
    adiabatic demagnetization
    permanent magnets
    2D field analysis
    3D field analysis
    Opis:
    Artykuł opisuje cykl przemiany energii w materiałach magnetokalorycznych, prototypy wybranych konstrukcji układów chłodzących, ich wady i zalety. Przedstawiono również tło polityczne i warunki środowiskowe wymagane przez UE w stosunku do urządzeń chłodniczych i klimatyzacyjnych.
    The magnetocaloric effect (MCE) is a thermodynamic process in which the temperature changes of a paramagnetic material are the effect of an external magnetic field changing in cycles. The refrigeration occurs in two stages: the first one is the isothermal magnetizing of the material, during which the intensity of the magnetic field rises from H0 to H3 (Fig. 1 process 1-2); during the magnetizing the dipoles of the paramagnetic material become arranged parallely to the intensity of the external magnetic field and the entropy of the material decreases from S1 to S2. As a result of magnetizing, heat is transferred to the surroundings in a quantity proportional to the work executed by the magnetic field. The second stage is the adiabatic demagnetization of the paramagnetic material to the value of the field intensity of H0, during which there occures a decrease in temperature of the material from Tp to T12 (Fig. 2 process 2-3).
    Źródło:
    Prace Instytutu Elektrotechniki; 2013, 261; 117-128
    0032-6216
    Pojawia się w:
    Prace Instytutu Elektrotechniki
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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