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1
Content available Performance comparison of double stator permanent magnet machines
Awah Chukwuemeka Chijioke
Archives of Electrical Engineering
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2022
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Vol. 71, nr 4
829--850
EN
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).
2
Content available Influence of rotor’s cage resistance on demagnetization process in the line start permanent magnet synchronous motor
Zawilak Tomasz
Archives of Electrical Engineering
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2020
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Vol. 69, nr 2
249--258
EN
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.
3
Content available Analysis of Current Signals in a Partially Demagnetized Vector Controlled Interior Permanent Magnet Generator
Quintal-Palomo Roberto Eduardo
Power Electronics and Drives
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2019
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Vol. 4 (39)
177--188
EN
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.
4
Content available Magnetization dependent demagnetization characteristic of rare-earth permanent magnets
Bavendiek Gregor, Müller Fabian, Sabirov Jamshid, Hameyer Kay
Archives of Electrical Engineering
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2019
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Vol. 68, nr 1
33--45
EN
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.
5
Content available Optimized design of a high-power-density PM-assisted synchronous reluctance machine with ferrite magnets for electric vehicles
Liu X., Li Y., Liu Z., Ling T., Luo Z.
Archives of Electrical Engineering
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2017
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Vol. 66, nr 2
279--293
EN
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.
6
Content available remote Demagnetization Fault Diagnosis in Permanent Magnet Synchronous Motors
Akar M., Eker M.
Przegląd Elektrotechniczny
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2013
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R. 89, nr 2a
229-233
EN
Permanent Magnet Synchronous Motors (PMSMs) are widely used in industrial automation systems due to their superiorities such as high efficiency and power factor, high power-weight ratio and high moment-inertia ratio. A new method to determine demagnetization faults in PMSMs has been presented in this study. The motor phase current has been monitored under differing speed and load conditions such as with stationary and non-stationary rotor speed and the demagnetization fault in PMSMs has been detected using Angular Domain Order Tracking (AD-OT) method. The obtained results have been compared with traditional Fast Fourier Transform (FFT) results. In conclusion, it has been observed that the proposed method has been successful in the detection of faults in stationary and non-stationary signals. Even though the proposed method has been used for a long time with vibration signals, it has been applied to PMSM current for the first time and very successful results have been obtained in the detection of demagnetization fault.
PL
W artykule przedstawiono nową metodę wykrywania demagnetyzacji w maszynie PMSM. W algorytmie wykorzystano metodę AD-OT (ang. Angular Domain-Order Tracking). Wyniki badań metody porównano z działaniem FFT. Proponowany algorytm skutecznie identyfikuje awarię zarówno w stanie ustalonym, jak i dynamicznym.
7
Content available Measures to reduce the residual field and field gradient inside a magnetically shielded room by a factor of more than 10
Voigt J., Knappe-Grüneberg S., Schnabel A., Körber R., Burghoff M.
Metrology and Measurement Systems
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2013
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Vol. 20, nr 2
237--248
EN
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.
8
Precyzyjne wymuszanie zerowej magnetyzacji przy pomiarach materiałowych
Mączeński Z., Rogowski J., Baszun M.
Elektronika : konstrukcje, technologie, zastosowania
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2008
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Vol. 49, nr 1
18-21
PL
Powszechnie stosowane, usankcjonowane normą IEC, elektryczne sposoby wymuszania zerowej magnetyzacji oparte na pobudzanych impulsowo obwodach rezonansowych, okazują się nieskuteczne przy bardzo precyzyjnych pomiarach nowoczesnych materiałów magnetycznych, takich jak np. magnetyki amorficzne, mikrokrystaliczne lub ferryty do zastosowań mikrofalowych. Zaproponowano cyfrową metodę precyzyjnego wymuszania magnetyzacji resztkowej B ro. Stosowanie tej etody spowodowało znaczne zwiększenie powtarzalności mierzonych charakterystyk materiałowych.
EN
Commonly used, IEC recommended, traditional demagnetization methods based on the pulse excited power resonant circuits, are almost of no use when modern amorphous, nanocrystalline and microcrystalline magnetic materials and ferrites for microwave application are to be precisely characterized. The method of forcing a precisely defined residual magnetization B ro has been proposed. A significant improvement in repeatability of measured magnetic characteristics has been obtained.
9
Content available remote The effect of wash cleaning and demagnetization process on the fly ash physico-chemical properties
Baliński A.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 2
125-128
EN
Problems related in this study concern the possibility of improving the physico-chemical properties of fly ash used as a base granular material in moulding mixtures. The investigations were carried out mainly to evaluate the process of the fly ash modification performed in order to stabilize its mineralogical and chemical composition. Changes in chemical composition, specific surface and helium density of fly ash after the process of its wash cleaning and demagnetization were examined. The analysis of the data has proved that the process of wash cleaning considerably reduces the content of sodium and potassium. Calcium and magnesium are washed out, too. The wash cleaning process of fly ash reduces also its true density. This fact can be due to the washing out of illite as well as some fractions of haematite (the grains weakly bonded to the glassy phase). The process of demagnetization allows removing about 25.7% of the magnetic phase calculated in terms of Fe2O3. The process of demagnetization is accompanied by a decrease in the content of aluminium, sodium, potassium and calcium, and a reduction in the size of the specific surface by over one half. The possible processes of transformation have also been discussed.
10
Content available remote Method of determining demagnetization resistance of commutator permanent-magnet machines
Dudzikowski I.
Archives of Electrical Engineering
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1999
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Vol. 48, nr 3
341-361
EN
A method of determining the allowable overcurrents, which do not results in the permanent demagnetization of the magnets, and the magnetic flux value after any current overloading of a motor, has been developed. It takes into account saturation and leakade of magnetic circuit, the influence of temperature, armature winding chording, commutating coil ampere-turns and nonuniformity in the demagnetization of the magnets. An analysis of the effect of the kind and dimensions of the magnets, temperature and the kind of the winding on the value of the magnetic flux and the demagnetization resistance has been carried out. Results of calculations are compared with measurements.
PL
Opracowano metodę wyznaczania dopuszczalnych przeciążeń prądowych nie powodujących trwałego odmagnesowania magnesów oraz wartości strumienia magnetycznego po dowolnych przeciążeniach prądowych silnika. Uwzględniono nasycenie i rozproszenie obwodu magnetycznego, wpływ temperatury, skrót uzwojenia twornika, przepływ zezwojów komutujących, nierównomierność w odmagnesowaniu magnesów. Przeprowadzono analizę wpływu rodzaju i wymiarów magnesów, temperatury i rodzaju uzwojenia na wartość strumienia i odporność na odmagnesowanie. Wyniki obliczeń porównano z wynikami pomiarów.
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