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1
Content available Scaling laws for the FE solutions of induction machines
100%
Nell M. , Lenz J. , Hameyer K.
Archives of Electrical Engineering
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2019
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tom Vol. 68, nr 3
677--695
EN
In this paper a scaling approach for the solution of 2D FE models of electric machines is proposed. This allows a geometrical and stator and rotor resistance scaling as well as a rewinding of a squirrel cage induction machine enabling an efficient numerical optimization. The 2D FEM solutions of a reference machine are calculated by a model based hybrid numeric induction machine simulation approach. In contrast to already known scaling procedures for synchronous machines the FEM solutions of the induction machine are scaled in the stator-current-rotor-frequency-plane and then transformed to the torque-speed-map. This gives the possibility to use a new time scaling factor that is necessary to keep a constant field distribution. The scaling procedure is validated by the finite element method and used in a numerical optimization process for the sizing of an electric vehicle traction drive considering the gear ratio. The results show that the scaling procedure is very accurate, computational very efficient and suitable for the use in machine design optimization.
2
Content available Influence of winding and shaft cooling on the thermal characteristics of a traction machine for heavy-duty distribution transport
100%
Groschup B. , Butterweck D. , Hameyer K.
Archives of Electrical Engineering
|
2023
|
tom Vol. 72, nr 3
769--784
EN
This paper studies the influence of different cooling technologies on the power density of a traction machine for heavy-duty distribution transport. A prototype induction machine is built with a housing cooling jacket, potted end-windings, entire winding cooling, and shaft cooling. Electromagnetic finite element and thermal lumped-parameter models are parameterized and verified using test bench measurements. The influence of each thermal resistance along the heat paths is studied and discussed. The results are used for studying different cooling technologies. The results indicate an improvement of the continuous power density up to 108% using shaft cooling and up to 15.6% using entire winding cooling.
3
Content available Magnetization dependent demagnetization characteristic of rare-earth permanent magnets
100%
Bavendiek G. , Müller F. , Sabirov J. , Hameyer K.
Archives of Electrical Engineering
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2019
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tom 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.
4
Content available Consideration of the spatial orientation of magnetic field quantities and tensile mechanical stress in the Finite Element Analysis of electrical machines
100%
Schauerte B. , Xiao X. , Jansen K. , Hameyer K.
Archives of Electrical Engineering
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2022
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tom Vol. 71, nr 4
949--961
EN
Due to speed-dependent centrifugal forces, the support of the torque, static mechanical stress introduced by manufacturing processes the laminated core of rotating electrical machines is exposed to considerable mechanical stress. The resulting stress distribution changes the magnetic properties of the electrical steel. To take this into account, a magnetization model is constituted on the basis of vector magneto-mechanical measurements that include the magnetic permeability as a function of the mechanical stress and the angle between magnetization - and the maximum principal stress direction. Subsequently, the model is integrated into the finite element simulation of a permanent magnet excited synchronous machine at different rotational speeds.
5
Content available Measurement and simulation of a rotational single sheet tester
100%
Müller F. , Bavendiek G. , Schauerte B. , Hameyer K.
Archives of Electrical Engineering
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2019
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tom Vol. 68, nr 1
173--183
EN
The accurate prediction of iron losses has become a prominent problem in electromagnetic machine design. The basis of all iron loss models is found in the spatial field-locus of the magnetic flux density (B) and magnetic field (H). In this paper the behavior of the measured BH-field-loci is considered in FEM simulation. For this purpose, a vector hysteresis model is parameterized based on the global measurements, which then can be used to reproduce the measurement system and obtain more detailed insights on the device and its local field distribution. The IEM has designed a rotary loss tester for electrical steel, which can apply arbitrary BH-field-loci occurring during electrical machine operation. Despite its simplicity, the proposed pragmatic analytical model for vector hysteresis provides very promising results.
6
Content available Multi-domain analytical rotor model with buried permanent magnets in V-arrangement for high-speed applications
100%
Lauerburg M. , Toraktrakul P. , Hameyer K.
Archives of Electrical Engineering
|
2023
|
tom Vol. 72, nr 3
629--641
EN
Different buried permanent magnet arrangements in rotors are compared based on electrical machines found in literature regarding high-speed capability. An analytical approach is presented to analytically calculate mechanical stresses in the bilateral and central bridge of V arrangements in order to determine the achievable circumferential velocity of a rotor geometry. The mechanical model is coupled to an analytical model which can determine the flux density in the main air gap under consideration of flux leakage within the rotor. The multi-domain model enables the analytical design of high-speed rotors with buried permanent magnets in V-arrangement.
7
Content available Control and Operation of a Hybrid Actuator for Maglev Applications
100%
Rickwärtz J. P. , Kolb J. , Franck M. , Hameyer K.
Power Electronics and Drives
|
2021
|
tom Vol. 6 (41)
128--143
EN
The hybrid actuator presented in this article is meant to enable stationary and slow dynamic levitation in Maglev applications. The term 'hybrid' refers to the design of the actuator, which is a combination of permanent magnets (PM) and electromagnets. This paper presents an analytically computable control algorithm for the said hybrid actuator. The theory of magnetic circuits is summarized shortly and used to derive a cascaded control loop consisting of an inner current controller and an outer air gap controller. Since the uncontrolled hybrid actuator is inherently unstable, the system has to be stabilized. By introducing a PID-controller into the air gap control loop, the unstable behaviour of the uncontrolled system is changed into the system behaviour of a damped harmonic oscillator. The advantage of this approach is that the computed controller parameters of the PID-controller can easily be adjusted, so the system behaviour of damping and eigenfrequency can be selected within a certain range. For the execution of the control algorithm, a microcontroller (MCU) is used and for precise air gap measurement, an eddy current sensor is installed. Finally, the behaviour of the current- and air gap controller is discussed for different measurement results and the adjustable system behaviour of the damped harmonic oscillator is presented.
8
Content available Hard magnetic material measurements in a pulsed field magnetometer considering coating and eddy current effects
100%
Kern A. , Leuning N. , Hameyer K.
Archives of Electrical Engineering
|
2023
|
tom Vol. 72, nr 2
407--414
EN
Rare-earth permanent magnets are coated in order to avoid corrosion. When considering the rated geometrical properties of a sample, the coating thickness has to be known precisely as it wrongly enlarges the magnetically active volume which in turn affects the accuracy of the measured magnetic properties. In this work, the sensitivity of hard magnetic material property measurements regarding the consideration of different coating thicknesses is evaluated. Moreover, the impact of eddy current effects on the magnetic properties is studied when measuring in an open circuit. Additionally, an outlook for a measurement-based determination of the electric conductivity of permanent magnet samples is given.
9
Content available Transient approach for iron loss separation of non-grain-oriented electrical steels considering the impact of cut edge effect
100%
Mülder C. , Elfgen S. , Hameyer K.
Archives of Electrical Engineering
|
2019
|
tom Vol. 68, nr 2
237--244
EN
The purpose of this paper is to focus on the loss separation of non-grain-oriented electrical steels used for speed-variable rotating electrical machines. The impact of laser-cutting, used in prototype manufacturing and of flux density harmonics, occurring locally in the lamination, on the loss distribution is studied in detail. Iron losses occurring under operation can physically be separated in different loss components. In this paper, a frequency-based loss model with parameters identified for single-sheet tester specimens, cut in strips of different widths, is therefore used. Moreover, a time-domain approach considers loss distributions occurring from higher harmonics. Hysteresis losses having high sensitivity to cut edge effects are calculated by the well-known Jiles-Atherton model adapting the frequency-based loss parameters. The model is validated by free-curve measurements at a single-sheet tester. It has been shown that the studied elliptical hysteresis model becomes inaccurate particularly for specimens with small strip widths with similar dimensions as teeth of electrical machine laminations. The incorrect mapping of losses occurring from minor hysteresis loops due to higher harmonics is concluded. The results showconsequently that both, the impact of a cut edge effect and local distributions of flux density harmonics need to be considered in terms of accurate iron loss prediction of electrical machine design.
10
Content available Low voltage winding insulation systems under the influence of high du/dt slew rate inverter voltage
100%
Pauli F. , Ruf A. , Hameyer K.
Archives of Electrical Engineering
|
2020
|
tom Vol. 69, nr 1
187--202
EN
Variable speed and low voltage electrical drives are commonly operated by frequency converters. According to recent developments, there is a trend in the area of semi-conductors, that switching frequency and voltage slew rate will increase significantly. The aim of these semiconductors is to reduce the switching losses and to increase the switching frequency, which enables to reduce the size of passive components in the powerelectric circuit. This results in less material effort and lower cost, for the power electronic component. However, electric motors operated by high slew rate inverters show problems in the winding insulation, which have to be analyzed. Such problems are well known for high voltage machines. Due to the increasing slew rate, this problematic occurs in low voltage machines nowadays as well. Here, the influence of fast switching semiconductors on the winding insulation system is studied, using accelerated ageing tests with fast switching high-voltage generators.
11
Content available Influence of thermal-mechanical stress on the insulation system of a low voltage electrical machine
100%
Yang L. , Pauli F. , Hameyer K.
Archives of Electrical Engineering
|
2021
|
tom Vol. 70, nr 1
233--244
EN
Varying ohmic loss in the winding of electrical machines, which are operated atvarious operating points, results in temperature changes during operation. Particularly, when the temperature is varying dynamically, the insulation system suffers from repeated thermal-mechanical stress, since the thermal expansion coefficients of the insulating materials and copper conductors are different. For the appropriate design of an insulation system, the effect of thermal-mechanical stress must be known. In the present work, motorettes are subjected to repeated thermal cycles. The expected lifetime is estimated and compared to the life time which is achieved by applying a lifetime-model which only considers thermal aging while ignoring thermal-mechanical stress effects. In addition, the hotspot temperature is simulated, the lifetime at the hotspot is estimated as the worst case. As expected, the results indicate that the thermal-mechanical stress plays a significant role during dynamic thermal aging of the winding insulation system. To better understand the thermal-mechanical stress effect, the resulting thermal-mechanical stress in a single wire is analyzed by the finite element method. A preliminary analysis of the aging mechanism of materials due to cyclic thermal-mechanical stress is performed with the theory of material fatigue.
12
Content available Comparison of concentrated winding topologies considering transient voltages in the winding system of inverter-driven low-voltage machines
100%
Pauli F. , Driendl N. , Mönninghoff S. , Hameyer K.
Archives of Electrical Engineering
|
2022
|
tom Vol. 71, nr 4
865--880
EN
To reduce the losses of the power electronic inverter, the voltage slew rate (d u/d t) of the electric motors supplying voltage is increasing. As steep voltage slopes excite high frequencies in the megahertz range, transient phenomena in the winding of the electrical machine occur. To design the insulation system, the maximum electric potential difference between the conducting elements must be predicted. General design rules can lead to a significant overengineering of the interturn insulation, particularly when considering smaller stators with a known wire distribution. Therefore, two different winding topologies are studied comparing the voltage distribution in a round-wire winding and a winding with preformed coils.
13
Content available Influence of conductive particle contaminationon the insulation system of rotating electrical machines with direct oil cooling
88%
Yang L. , Pauli F. , Zhang S. , Hambrecht F. , Hameyer K.
Archives of Electrical Engineering
|
2022
|
tom Vol. 71, nr 3
789--804
EN
An integration of the electrical machine and the gearbox is attracting particular attention for the design of modern electric and hybrid drive trains, since it saves overall space and subsequently increases the power density. Another benefit of a high level of integration is that it enables a combined application of oils as both cooling fluid for the electrical machine and as lubrication fluid for the transmission system. In this way, the power density of the integrated drive train can be further increased. During the oil cycling, conductive contaminations may be introduced and subsequently have an influence on the function of the insulation system of the electrical machine. In the present work, the influences of the cooling oil and its conductive contaminations, conductive particles as well as their combination with humidity, on the electrical and dielectric properties of the insulation system are studied. The results show that by application of the cooling oil, the partial discharge inception voltage (PDIV) of the winding insulation increases significantly so that an electrical breakdown is prone to happen before a partial discharge (PD) occurs. With increasing particle contamination, the PDIV of the insulation system decreases significantly, while the capacitance increases. Besides, conductive particles and humidity decrease the surface resistance and surface breakdown voltage of the insulation papers significantly. The results indicate that the conductive particle contaminations can play an important role for the electrical degradation of the insulation system.
14
Content available Magnetic anisotropy under arbitrary excitation in finite element models
75%
Bavendiek G. , Leuning N. , Müller F. , Schauerte B. , Thul A. , Hameyer K.
Archives of Electrical Engineering
|
2019
|
tom Vol. 68, nr 2
455--466
EN
Magnetic properties of silicon iron electrical steel are determined by using standardized measurement setups and distinct excitation parameters. Characteristic values for magnetic loss and magnetization are used to select the most appropriate material for its application. This approach is not sufficient, because of the complex material behavior inside electrical machines, which can result in possible discrepancies between estimated and actual machine behavior. The materials’ anisotropy can be one of the problems why simulation and measurement are not in good accordance.With the help of a rotational single sheet tester, the magnetic material can be tested under application relevant field distribution. Thereby, additional effects of hysteresis and anisotropy can be characterized for detailed modelling and simulation.
15
Content available On magnetization deviations as the dominant cause for vibration harmonics in the spectrum of a PMSM drive
75%
Jaeger M. , Drichel P. , Schröder M. , Berroth J. , Jacobs G. , Hameyer K.
Archives of Electrical Engineering
|
2021
|
tom Vol. 70, nr 3
719--730
EN
Production deviations have a remarkable effect on the radiated sound of electrical machines, introducing additional signal components besides the fundamental field waves which significantly change and enrich the subjectively perceived sound characteristic. In literature these harmonics are mainly traced back to dynamic eccentricity, which modulates the fundamental field waves. In this paper a thorough mechanic and electromagnetic analysis of a modern, well-constructed traction drive (permanent magnet synchronous machine) is performed to show that for this typical rotor configuration dynamic eccentricity is negligible. Instead, deviations in the rotor magnetization are shown to be the dominant cause for vibration harmonics.
16
Content available remote Evaluation of the interdependency of mechanical cutting and magnetic anisotropy on the magnetic properties of FeSi electrical steel
75%
Leuning N. , Steentjes S. , Weiss H. , Volk W. , Schultz M. , Neuwirth T. , Hameyer K.
Przegląd Elektrotechniczny
|
2019
|
tom R. 95, nr 7
1--6
EN
Due to present-day challenges for the improvement of the operating characteristics of rotating electrical machines, the core material is regarded as increasingly important. Non-oriented (NO) electrical steel sheets are conventionally used for the construction of magnetic cores of rotating electrical machines. The most appropriate choice of material and machine design is based on standardized material data obtained from Epstein frames or single sheet testers. Both, low losses as well as good magnetizability in any spatial direction of the sheet plane are requested. Despite their name, NO electrical steels do show a magnetic anisotropy. A significant increase of loss and decrease of permeability can additionally be induced by mechanical cutting processes to shape the magnetic circuit. Magnetic anisotropy and induced mechanical stress can affect the local iron-loss distribution, magnetizability, acoustic behavior and therefore, have to be considered in numerical simulations of electrical machines. In this paper, the interdependency of the magnetic anisotropy with the effect of cutting is studied in order to improve the necessary understanding of the material behavior.
PL
W procesie mechanicznego cięcia blchy elektrotechnicznej mogą ulec degradacji podstawowe jej parametry – straty I przenikalność. Indukowane w procesie cięcia naprężenia wpływają na anizotropię I rozkład strumienia. W artykule W artykule analizowany jest wpływ procesu cięcia na właściwości niezorientowanych blach elektrotechnicznych.
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