Search

A coaxial magnetic gear (CMG) consisting of an inner ring, outer ring, and flux modulator exhibits relatively large torque density at low operating cost and low noise level. To guide the selection of soft magnetic materials for the flux modulator, this paper first incorporates the Jiles–Atherton model within a finite-element (FE) framework. The influence of nonlinear magnetic properties on end-effect losses (magnetic flux leakage and fringing) is then investigated with the objective of maximizing the pullout torque. For flux modulators whose initial magnetic permeability and saturation flux density exceed certain threshold value, the pullout torque of a CMG becomes insensitive to magnetic properties and end-effect losses can be efficiently calculated from a 2-D FE model together with a constant torque reduction ratio. This paper presents a systematic torque surface method that can decouple the analysis of average torque and torque ripples. This method has been implemented to evaluate load dependence and rotation speed fluctuation of a CMG. [ABSTRACT FROM AUTHOR]

Non-oriented (NO) electrical steels are widely used as core materials in rotating electrical machines, whereas for measurements under alternating magnetization (AM), standardized methods exist; measurements under rotational magnetization (RM) prove to represent a significant problem. In this paper, we performed measurements of both circular rotational and alternating losses in rolling and transverse directions for four types of NO materials of different Si contents and thicknesses by means of a hexagonal rotational single-sheet tester at different frequencies and flux density values. The losses were measured by the electrodynamical method and for confirmation also by the thermal (rise-of-temperature) method. The estimated rotational losses by means of established well-known methods are correlated with the measured ones. Literature reports attempt to estimate losses $P^{\mathrm {(RM)}}$ for circular RM on the basis of losses $P^{\mathrm {(AM)}}$ for AM. A loss ratio factor $\Gamma = P^{\mathrm {(RM)}}/P^{\mathrm {(AM)}}$ is defined which is reported to be close to $\Gamma = 2$. In this paper, $\Gamma $ factors were determined for three different grades of material. The results indicate a rather weak dependence of $\Gamma $ on the grade, however, a strong one on the intensity $B$ of induction. In approximation, $\Gamma = 2$ is valid for rather weak induction of the order $B = 0.6$ T. Induction increases in steps of $\Delta B = 0.1$ T yield decreases of loss ratio by about $\Delta \Gamma = 3$ %. This enables a rough estimation of rotational losses. However, the possibility of estimation is restricted to the circular case of constant modulus and angular velocity of the $B$ vector. Other cases are characterized by different values of both eddy current losses and hysteresis losses, RM involving completely different domain reconstructions compared to AM. For increased frequency, the decrease in $\Gamma $ becomes weaker due to more dominant eddy current losses. [ABSTRACT FROM AUTHOR]

Accurate modeling of soft- and hard-magnetic materials for the numerical simulation of rotating electrical machines is required to allow predictions on the operational characteristics along the torque–speed map, already in the design stage. The full potential of most appropriate material selection and concurrent geometry adaption can only be utilized if models can represent actual material behavior. The accurate prediction of iron losses of soft-magnetic materials for various frequencies and magnetic flux densities, as well as the degradation due to manufacturing is eminent for the design of electrical machines. Therefore, advanced material models need to be adapted and their accuracy examined to further improve the modeling and enable progression. This paper will give an overview of the current modeling approaches applied at the Institute of Electrical Machines for soft- and hard-magnetic materials in the simulation of rotating electrical machines. A case example in the form of a traction drive is presented to which the models are applied. For the machine modeling, the inhouse solver pyMOOSE is utilized. In order to determine the losses with regard to manufacturing processes, the iron-loss model with material degradation is used in combination with a machine simulation scheme of the entire operating range of the machine. Here, various simulation approaches are combined to form the entire computational toolchain to obtain accurate results in the entire operational range. [ABSTRACT FROM AUTHOR]

In this paper, the iron loss models for electrical machines are first reviewed. One of the most accurate iron loss models, when the temperature is constant, is identified. An improved temperature-dependent iron loss model is also introduced. By applying the improved iron loss model to the electrical machine thermal analysis, the thermal and loss analyses can be fully coupled. Based on this, an improved thermal-loss coupling analysis method for electrical machine is developed in this paper. The electrical machine iron loss tests are carried out. The analysis and measurement results are then compared in order to validate the improved thermal-loss coupling analysis method. The comparison results indicate that the temperature prediction accuracy can be significantly improved by using the improved thermal-loss coupling analysis method. [ABSTRACT FROM AUTHOR]

In this paper, optimization of the control of an electrical machine allowing a minimization of its total losses is described. It is based on the use of an iron loss model [loss surface (LS) model] coupled to the electromagnetic finite-element simulations of the machine. The LS model is a scalar and dynamic hysteresis model developed many years ago at G2Elab and tested for iron loss prediction in several cases of electric machines. It is first characterized and improved in this paper for M330-35A SiFe sheets. Then, it is associated with a finite-element analysis to compute, in a post-processor mode, the local and global magnetic losses in the machine. For electric vehicle application, the whole torque–speed variation should be investigated. To do that, a quick response surface is constructed from a small number of simulations and the iron loss is determined. Then, a suitable optimization algorithm is developed. This approach is then illustrated by a case study and compared with classical optimization in which only the copper losses in conductors are considered. Gains of up to 50% reduction in the total losses of the machine in certain operating areas are observed. [ABSTRACT FROM AUTHOR]

In previous studies on precise computation methods of iron loss, it has been shown that the 1-D dynamic magnetic field analysis with hysteresis in post-processing is effective. However, there is a problem in that the hysteresis makes the convergence of nonlinear iterations unstable. This paper proposes a stabilization method for the 1-D dynamic magnetic field analysis with hysteresis. The proposed method is characterized as an approach for improving the initial value and the step size in the Newton–Raphson method. The results of this paper showed that the convergence characteristic of the nonlinear 1-D magnetic field analysis for variety flux density waveforms of each part in an electric motor is improved using the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the dc biasing magnetomotive force (mmf) in presaturated core fault current limiter (PCFCL) is replaced with permanent magnet (PM) to overcome the well-known drawbacks of the dc biased PCFCLs. These drawbacks are excessively induced voltage across the terminals of the dc coil during fault condition and high total power losses during the steady-state condition. The novel contributions of this paper are the introduction of the selection criteria of PM material and its representation by actual nonlinear $B$ – $H$ hysteresis loop of Jiles-Atherton method, and the use of PM alone as an equivalent to the dc biasing coils for three-phase fault current limiter (FCL), contrary to work reported in earlier papers. Single- and three-phase PCFCLs are modified by replacement of dc saturation coil by the equivalent PM through time-domain finite element (FE) simulation of COMSOL Multiphysics package. Experimental verification shows that the implementation of accurate nonlinear representation of PM demagnetization curve with FE simulation gives a realistic performance of the PM biased PCFCL, especially in the fault condition. The performance of PCFCL can be evaluated through the voltage drop and total power losses during the steady-state condition and the fault current clipping ratio during fault condition of the grid. Furthermore, a comparative investigation of dynamic behavior is considered between dc and PM biased PCFCLs. It is found that the PM biased PCFCL has enriched capability of limiting any type of fault current with leading advantages of reduced voltage drop and power losses significantly together with risk elimination of the high induced voltage across dc coil terminals. Moreover, the governing parameters of PM biased PCFCLs are subjected to performance analysis to study their inherent effects. [ABSTRACT FROM AUTHOR]

This paper proposed a temperature-dependent iron loss model and corresponding dynamic hysteresis model, where temperature coefficient k is introduced to consider the thermal effect on eddy-current loss. The iron loss model is validated by massive experimental measurement of test samples, 1174 combinations of various temperatures, magnetic inductions, and frequencies for nonoriented silicon steel specimen. The relative error of the model is $\sim 11$ % in a wide range of 50–400 Hz, 26 °C–200 °C, and 0–2 T. The proposed method can be applicable to other types of magnetic materials as long as whose resistivity rate exhibits approximately linear thermal dependence within a temperature range of 26 °C–200 °C. [ABSTRACT FROM AUTHOR]

This paper presents the characteristic analysis and experiment of surface-mounted type variable-flux permanent-magnet machines considering magnetization and demagnetization based on electromagnetic transfer relations. For this purpose, we derive the analytical solutions for the magnetic fields generated by the magnetization level of AlNiCo magnets and currents on the basis of the transfer relations in terms of a 2-D polar coordinate system. The magnetization levels of the AlNiCo magnets are determined by the magnetic fields generated by the armature reaction field. A 2-D permeance function is also introduced to consider slotting effects. The analytical results of the magnetic field are validated extensively with finite-element (FE) analyses. On the basis of these solutions, the induced voltage is also determined analytically. Finally, the predictions are compared with FE analyses and measured data to confirm the validity of the analysis methods presented in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates the effectiveness of the Cauer circuit modeling for dynamic hysteretic property in iron loss analyses of rotating machines. We apply the method to an interior permanent magnet synchronous motors fed by pulsewidth modulation inverter and compare their performance with a conventional iron loss estimation method based on 1-D finite-element analyses. As a result, almost the same iron loss is obtained by using the Cauer circuit modeling with lower computational cost. [ABSTRACT FROM AUTHOR]

One of the issues of an iron loss estimation is the modeling of an excess loss. This paper investigates the modeling method for the excess loss under dc-biased conditions. The proposed approach is based on the 1-D finite-element analysis for the silicon steel sheet in the thickness direction considering hysteretic property and skin effect. In addition, the magnetic flux density waveform is divided into the outline loop and minor loops and estimate the excess loss of each loop using the eddy current loss correction factor $\kappa $ taking account of dc-biased conditions. To demonstrate the effectiveness of the proposed method, we compare the estimated loss with measured one for the harmonic wave in single sheet tester. [ABSTRACT FROM AUTHOR]

In this paper, the magnetic properties of non-oriented (NO) and grain-oriented (GO) silicon steels with dc-biased induction are measured and analyzed within the wide range of 20–1000 Hz, 0–1.9 T. While by the physical method, we found that all the ac-, dc-, and dc-biased fields do not influence the electrical resistivity of silicon steel, and hysteresis loss is mainly responsible for the iron loss increase when dc-biased induction exists. With the frequency and ac induction going up, the effect of dc-biased induction on iron loss will become weak. Compared with NO steel, iron loss of GO steel is more sensitive to dc-biased induction. The validation shows that existing iron loss models which claim to consider dc-biased magnetic induction are not satisfactory up to now when applied in the wide range of dc-biased induction, ac induction, and frequency. [ABSTRACT FROM AUTHOR]

In the design process of permanent magnet synchronous motors (PMSMs), the hysteresis torque has so far been ignored under the understanding that it is already small enough. However, for some delicate applications, such as an exoskeleton wearable robot, the hysteresis torque, whose proportion increases under no-load or low-load conditions, needs to be further minimized even though the hysteresis torque has low magnitude. Conventional methods using hysteresis models to calculate the hysteresis torque require a lot of computation resources. Therefore, this paper proposes a simpler method in order to estimate the hysteresis torque using iron-loss experimental data. In the proposed method, the hysteresis torque is derived from the hysteresis loss, which is separated from the iron-loss experimental data by using the modified Steinmetz equation. Finally, the hysteresis torque of the proposed surface-mounted PMSM is measured via experiments to verify the validity of the proposed method. The hysteresis torque is obtained by subtracting the mechanical friction torque from the no-load offset torque. The experimental result is compared with the results obtained from the proposed method. [ABSTRACT FROM PUBLISHER]

This paper develops an approach to evaluate and predict the effect of punching processes upon the performance of switched reluctance motors (SRMs). Punching is a common process for manufacturing of electric motors although the magnetic performance of the electrical steels at the cut edges may degrade. This could then result in a lower motor performance than expected. Annealing can usually restore the material property but it would be costly for production of common electric motors. Therefore, it is useful to compensate this effect in the design of electric motors. In this paper, the damaged range due to punching is modeled and included in the finite-element simulation for the SRMs such that the effect of this damage can be evaluated. The material properties at the cut edges are determined using the techniques developed here. Two SRMs are investigated: one being annealed after punching and the other not before assembly. Test results show that the annealed SRM produces a better performance. The comparison between the simulations and experiments shows that the developed method can be used for analysis of punching effect on motor performance. [ABSTRACT FROM AUTHOR]

This paper studies the effect of common-mode voltage elimination (CMVE) on the iron loss of electrical machine core laminations under multilevel converter supply. Three identical magnetic ring cores are excited by either a three-level converter or a five-level voltage source converter to study the behavior of CMVE on a three-phase system. Both multilevel converters are controlled by using a space vector pulsewidth modulation as it is one of the most often used techniques for CMVE. These experimental results are confirmed numerically with a dynamic iron loss model. In addition, the effect of CMVE, at different switching frequencies, on the core loss of a synchronous machine is numerically studied. The results presented in this paper show that the core loss is considerably increased when the CMVE is implemented. However, this iron loss increase in the five-level drive systems is lower compared with the three-level ones. Therefore, it is important that the designers of drive systems take such effects into consideration. [ABSTRACT FROM AUTHOR]

With the change of temperature, magnetic characteristics of electrical steel sheet (ESS) exhibit remarkable variations, in particular, at high-temperature region. If the magnetic field of electromagnetic devices operating under high temperature is analyzed by the magnetization data recorded under room temperature, the analysis findings appear to be quite different from the real ones. In order to understand and apply the real magnetic behavior in ESS, a temperature-dependent hysteresis model is quite necessary. In this paper, a physical background-based Jiles–Atherton (J–A) model is enhanced for revealing temperature effects through the introduction of temperature-dependent parameter on the base of observation of measurement data. In addition, the inaccuracy of J–A model in the range of weak applied field is enhanced with the use of variable parameter set. Ultimately, a comprehensive improvement algorithm of temperature-dependent J–A model is proposed followed by verification through experimental hysteresis data. [ABSTRACT FROM AUTHOR]

This paper used a finite-element magnetic field analysis (FEA) to investigate the instantaneous and average power in a single phase transformer and a three-phase rotating machine. We examined the influence of the hysteretic properties of the magnetic materials on the instantaneous power in FEA using the isotropic vector play model. We applied post-correction to estimate the accuracy of the average power from their equivalent circuits. [ABSTRACT FROM AUTHOR]

In many electromagnetic energy conversion processes, transformers, or electric machines are controlled with modern power converters at high frequencies up to a range of several 10 kHz. Such operation modes lead to not negligible, distinct iron losses in the flux-leading laminated core. For estimating iron losses, no universally valid equation is available covering transient effects and nonlinear magnetization processes at the same time for a wide frequency range. Sophisticated 2-D and 3-D models are available but these hysteretic models are computationally very intensive when applied in a finite-elements method. This paper presents a 1-D iron-loss model, which allows estimating the static and dynamic hysteresis losses during the electromagnetic energy conversion processes with low computational effort. The proposed model can be used as lumped circuit element in a spatial magnetic equivalent network representing an electromagnetic device e.g., an induction machine. The model is based on a loss-separation approach, in which the different magnetization-loss mechanisms are interpreted corresponding to an analogous mechanical model. The proposed approach is implemented in Modelica; the model setup and the simulations are performed in Dymola. The validation of the developed iron-loss model is performed with measurements conducted on an Epstein frame. [ABSTRACT FROM AUTHOR]

This paper presents a simple dynamic vector-play model to calculate the iron loss and describe the vector hysteresis behavior of a non-oriented (NO) electrical steel sheet (ESS) under 50 Hz rotating magnetic fields. Based on the iron loss separation theory, the proposed model is separated to the static hysteresis component and eddy current component. The static hysteresis component is constructed by vector play model, which is identified by using 1 Hz minor B – H loops. And two coefficients \omega x and \omega y are introduced to consider the anisotropic property of NO ESS and the excess loss of eddy-current component under 50 Hz magnetic field. The validity of the proposed dynamic vector hysteresis model is verified by comparing it with the experimental results under various 50 Hz magnetic field conditions. [ABSTRACT FROM AUTHOR]

In the frame of this paper, the synthesis of self-assembled magnetic and biocompatible nanovehicles movable in aqueous solutions by a magnetic field gradient is presented. The systems consist of a mesoporous silicon template and encapsulated iron oxide nanostructures, both materials known to be biocompatible. Two routes are applied to produce iron oxide nanostructures embedded within porous silicon. First, readily synthesized superparamagnetic iron oxide nanoparticles (NPs) are infiltrated into the pores. The second attempt is the chemical deposition of iron oxide structures inside the PSi templates. Concerning the adjustability of the magnetic properties of the system the loading procedure of the PSi with iron oxide NPs will be elucidated in detail as well as the growth of iron oxide structures within the pores. An assessment of the iron oxide deposition dependent on the template and the chemical parameters as well as of the magnetic properties in dependence on the particle size and template morphology of the nanocomposite will be presented. A further approach is the transition from a magnetite to the stable hematite phase by heat treatment of the specimens. A sufficient filling leading to a magnetization high enough for the movement of the nanovehicles within aqueous surroundings (e.g., body fluid) by magnetic field gradients could be reached easily. [ABSTRACT FROM AUTHOR]

The goal of this paper is to investigate the accuracy of modeling the excess loss in electrical steels using a time domain model with Bertotti’s loss model parameters n0 and V0 fitted in the frequency domain. Three variants of iron loss models based on Bertotti’s theory are compared for the prediction of iron losses under sinusoidal and non-sinusoidal flux conditions. The non-sinusoidal waveforms are based on the realistic time variation of the magnetic induction in the stator core of an electrical machine, obtained from a finite element-based machine model. [ABSTRACT FROM AUTHOR]

This paper deals with the evaluation of various dynamic models for modeling of three-limb core power transformers. Due to the specific construction of such transformers, the magnetic fluxes in individual core limbs are interdependent. For applications, such as simulations and testing protection devices and algorithms, adequate prediction of inrush currents waveforms is crucial and indispensable. In this paper, various different dynamic models are tested where the limitations of standard models that are available in commercial program packages are pointed out. Two groups of models are evaluated separately: standard three-phase models composed of three-single phase transformer models and advanced three-phase models, where the topology of the magnetic circuit is considered. Furthermore, in both transformer model groups, three different material descriptions are evaluated, where linear, non-linear, and hysteretic material properties are considered. The comparison between measured and calculated waveforms of inrush currents is used to evaluate individual models. The comparison of evaluated models shows that standard dynamic models cannot provide proper waveforms of inrush currents regardless of which magnetically non-linear behavior of the iron core is considered. For adequate modeling of discussed transformers the consideration of the topology of the magnetic circuit is crucial. [ABSTRACT FROM AUTHOR]

This paper presents iron loss distributions in divided-stator model cores calculated with the finite-element method considering vector magnetic properties. The magnetic anisotropy and rotational iron loss were considered using the dynamic E&S modeling. In this paper, we discuss the differences of the calculated results depending on the direction of the magnetic anisotropy in the divided cores. Moreover, the effect of difference of the junction position of the divided-stator cores on the total iron loss is investigated. [ABSTRACT FROM AUTHOR]

This paper proposes a model for the computation of iron losses in steel laminations accounting simultaneously for magnetic hysteresis and eddy currents. The proposed model is well suited for finite element implementation and relies on a consistent thermodynamic background. The focus of this paper is particularly set on a systematic and accurate identification of material parameters from standard dc measurements (Epstein frame, single-sheet tester). Once identified, those material parameters can be used to obtain quantitative predictions of iron losses at higher frequencies and in the presence of higher harmonics. The model and the identification process are validated against measurements for a M235-35 A electrical steel over a wide range of field intensity and frequencies. [ABSTRACT FROM AUTHOR]

This paper proposes a novel estimation method for iron loss considering hysteretic property. In the proposed method, iron loss considering hysteretic property is estimated with play model as a postprocessing of usual finite element magnetic field analysis based on ordinary magnetization curve. Numerical results are compared with measured results to demonstrate the effectiveness of the proposed estimation method for iron losses. [ABSTRACT FROM AUTHOR]

This paper proposes a homogenization method for a laminated iron core taking into account hysteretic property. The proposed method is applicable to a static or low-frequency problem neglecting eddy currents induced by the magnetic flux parallel to the lamination. Furthermore, we apply the proposed homogenization method to finite-element magnetic field analyses to demonstrate its effectiveness. As a consequence, it is verified that the proposed homogenization method can accurately estimate a hysteresis loss of a laminated iron core and decrease computational costs. [ABSTRACT FROM AUTHOR]

This paper deals with the acoustic noise emissions caused by a welding transformer (WT) operating as part of a middle-frequency direct current resistance spot welding system (RSWS). The WT consists of an iron core, one primary winding, and two secondary windings. The primary winding is supplied by the voltage from the input converter while the full-wave diode output rectifier is connected to the two secondary windings in order to generate a direct welding current. In the case study, the alternating current primary voltage is generated in two different ways, by applying a pulse width modulation and two hysteresis controllers. The aim of this paper is to analyze how the voltage generation method influences the acoustic noise emissions caused by the WT. The analysis is based on the values of the supply current, the welding current, and the iron core flux density measured on a 160 kW industrial WT operating as a part of laboratory RSWS where the supply voltage is generated in two different ways. The results presented in the paper show that proper voltage generation method can substantially reduce the acoustic noise emissions caused by a WT. [ABSTRACT FROM PUBLISHER]

This paper presents a generalized dynamic hysteresis model for estimating the iron loss of complex flux waveforms. A versatile measurement system is developed to experimentally investigate the magnetic and iron loss properties of the studied soft magnetic material over a wide range of ac and dc excitation. With the measured hysteresis loop data available, an improved dynamic hysteresis model is proposed to properly include the impact of the flux density changing rate, instantaneous magnetization state, and time history of magnetic flux on dynamic field modeling. Experimental results have confirmed the desired accuracy of iron loss predictions over broad operating ranges, including conditions of pure sinusoidal fields, non-sinusoidal flux waveforms with superimposed harmonics, and flux waveforms in the presence of pre-magnetized dc-bias fields. The model parameters identified from symmetrical hysteresis loops can be utilized to predict the iron loss over a variety of conditions, making it a generalized tool for the iron loss estimation of complex flux waveforms. [ABSTRACT FROM AUTHOR]

Two compounds with the same composition of Mn 1.15 Fe 0.85 P 0.65 Si 0.13 Ge 0.2 B 0.02 have been synthesized by traditional sintering (TS) and spark plasma sintering (SPS) methods. A comparative study on the structural and magnetic properties of the compounds has been carried out using X-ray diffraction (XRD), scanning electron microscopy, and magnetic measurements. The XRD results reveal that both compounds crystallized mainly in the Fe 2 P-type hexagonal structure. The TS-prepared sample exhibits large holes and worse densification due to the evaporation of P, when comparing with the SPS-prepared sample. The Curie temperatures are found to be 251 and 291 K on cooling, and 261 and 298 K on heating for the compounds prepared by SPS and TS, respectively. For a field change of 3 T, the maximum values of isothermal entropy changes are found to be 15.1 and 7.9 J/kgK for the compounds prepared by SPS and TS, respectively. These results are correlated with the practical concentration of P in the compounds. This paper indicates that the SPS technique is suitable for synthesizing the Fe 2 P-type bulks with good magnetocaloric properties. [ABSTRACT FROM AUTHOR]

In this paper, an analytical approach allowing the prediction of iron-core losses in flux-modulated permanent-magnet synchronous machines. According to the Maxwell–Fourier method (viz., the multi-layer model) and Cauchy’s product theorem, the magnetic field distribution is determined in different parts of machine by considering the iron permeability on the basis of solving both Poisson’s and Laplace’s equations. Next to the dc bias flux density and the minor hysteresis loops, which are taken into account, the Bertotti’s model and the flux variation locus are employed to calculate the iron-core losses under load and no-load conditions in post-processing from the magnetic field analytical calculation. Finally, in order to validate the proposed analytical method, the results are verified by the comparison with the finite-element method. The comparisons show good results of the proposed model. [ABSTRACT FROM AUTHOR]

In this paper, an excess loss modeling method of the laminated iron core is proposed. The 1-D single sheet silicon steel plate analysis is combined with the 3-D solid-core analysis to model the laminated structure. The modeling is improved by including the domain wall bowing due to pinning effect, which is considered as the main cause of excess loss. The domain wall bowing due to pinning is considered in the 1-D steel plate analysis because the excess loss generated by the flux density in the parallel direction of the stack is dominant compared with that in the perpendicular direction. In the 1-D analysis, an initial bowing flux distribution along the thickness direction of one lamination is introduced. The results of iron losses show that the hysteresis and eddy current losses vary with the flux and eddy current distribution in the laminated iron cores. Finally, the 1-D–3-D combined method is applied to a single-phase reactor; the magnetic flux and eddy current distribution are analyzed in detail. The eddy currents generated by the parallel flux are increased, hence, the skin effect of flux in the parallel direction of laminations is enhanced; thus, the hysteresis and eddy current losses are increased and the iron loss is increased by 8%. [ABSTRACT FROM AUTHOR]

This paper proposes a novel dual-sided permanent magnet memory machine (DSPM-MM) by combing the distinct advantages of “high torque density” of conventional rotor-PM machine and “convenient online PM flux control” of stator-PM MM. In the proposed design, the consequent-pole NdFeB PMs are placed in the rotor, whereas the low coercive force (LCF) PMs are mounted between the adjacent stator teeth to enable flexible air-gap flux adjustment. Meanwhile, since the LCF PMs can be either remagnetized or demagnetized bidirectionally by a current pulse, the associated flux-weakening copper loss is eliminated, and hence, the proposed DSPM-MM can maintain high efficiency operation over a wide operating range. The machine topology and operating principle are introduced and addressed from the perspective of the nonlinear hysteresis behavior of LCF PMs as well as dual flux modulation effect, respectively. Then, the electromagnetic characteristics of the proposed machines having various available rotor poles are investigated and compared. The feasibility of the proposed design is validated by both finite element and experimental results. [ABSTRACT FROM AUTHOR]

Shape-giving production steps in the manufacturing of electrical machines often introduce plastic deformation and residual stress into the soft magnetic material, thus decreasing the magnetic quality and locally increasing both the static and dynamic hysteresis losses near the cut edges. Different models have been published, aiming to describe the changing local magnetization and loss behavior. Current approaches often consider permeability deteriorations by subdividing the soft magnetic material into the slices of different material properties. Three cut edge models are discussed here, where two describe the changed local polarization and the third estimates the resulting global iron losses. This paper presents a continuous material model for an efficient numerical model of the local magnetization. By replacing effortful sliced models, the continuous model is independent of the discretization and converges in the case of coarse meshes to the sliced model. [ABSTRACT FROM AUTHOR]

This paper describes an analysis method for inductance and iron loss considering the magnetic hysteresis property in reactors. We discuss inductance calculation methods based on magnetization curves and hysteresis loops. Furthermore, we propose a novel iron loss analysis method under ac excitation with single high-frequency ripples with low computational cost. These numerical results are compared with the experimental results. [ABSTRACT FROM AUTHOR]

The design of energy-efficient electrical machines requires the accurate estimation of iron loss. There are minor hysteresis loops in the case in which a flux density waveform includes higher harmonics, and it is possible that the conventional iron loss calculation methods do not accurately estimate minor-loop loss. Therefore, iron loss of the hysteresis loop with minor loops estimated using a conventional iron loss calculation method could differ from measurements. This paper investigates a method of calculating iron loss based on the dc-biased magnetic properties. [ABSTRACT FROM AUTHOR]

This paper investigates a novel estimation method for iron losses considering hysteretic property and skin effect simultaneously. In the proposed method, iron losses considering both hysteretic property and skin effect are estimated by utilizing a 1-D finite element method as a postprocessing of the usual 2-D analyses based on ordinary magnetization curve. To demonstrate the effectiveness of the proposed iron loss estimation method, we compare numerical results with measured ones. Furthermore, the proposed method is applied to iron loss analysis of an interior permanent magnet motor fed by pulsewidth modulation inverter. [ABSTRACT FROM PUBLISHER]

This paper presents the topology optimization of a synchronous reluctance motor using the normalized Gaussian network. In the optimization, the average torque and iron loss are considered. In the resultant motor, the area of the rotor surface adjacent to the stator is found to be reduced when the weight for the iron loss is sufficiently large. On the other hand, large flux barriers are present in the rotor when the average torque is maximized without considering the iron loss. [ABSTRACT FROM PUBLISHER]

In this paper, a comparative study of the effect of different converter topologies on the iron loss of nonoriented electrical steel is presented. Three converter topologies are considered in this investigation; namely: two-, three-, and five-level power converters. Moreover, the effect of the carrier frequency on both the iron loss and converter loss is introduced. The experimental results show a dramatic increase of the iron loss for the two-level converter, especially for low levels of the carrier frequency. Furthermore, the increase of the iron loss is negligible for the multilevel converter topologies. Specifically, the use of the five-level converter, even at a low value of the carrier frequency, results in lower iron losses than the three-level converter at a relatively higher carrier frequency. [ABSTRACT FROM AUTHOR]

The decrease in magnetic permeability and increase of local hysteresis loss in the vicinity of lamination edges originating from the cutting process need to be accounted for during the design of electrical machines. A flexible method is needed, which is able to account for different degradation profiles due to different cutting techniques. This paper presents a quantitative analysis of the impact of material degradation on iron losses and magnetizability due to guillotine shear and CO2 laser cutting for non-oriented electrical steels. [ABSTRACT FROM AUTHOR]

The study of iron losses in electrical machines represents a major interest in academic and industrial environment, especially in case of systems with high-frequency (HF) harmonic content in the supply voltage. In this context, this paper presents an analysis concerning the impact of HF injection on low-frequency (LF) iron losses. A new phenomenon is observed in a toroidal magnetic circuit with nonoriented electrical steel laminations, supplied by the superposition of two sinusoidal voltages at low and high frequencies. The experimental results show that the injection of HF harmonics (0–10 kHz) in the toroid affects the distribution of low frequencies in the steel in a way that the LF iron losses decrease of about 25%. An explanation for this phenomenon might be attributable to motion mechanism of Bloch walls. [ABSTRACT FROM AUTHOR]

We calculate an iron loss attributed to semiconductors ON-voltages in an inverter circuit and reveal influence rate of the ON-voltages on whole iron loss. In our previous work, it has been revealed by inverter excitation that the ON-voltages make minor loops in magnetic hysteresis of magnetic material and the loops affect iron loss characteristics. In this paper, it is investigated by a factor analysis how much the on-voltage has an influence on iron loss, quantitatively. We separate whole iron loss caused in a non-oriented electrical steel sheet into three losses: loss by the ON-voltage, loss by fundamental component, and loss by inverter carrier. The rates of these losses are evaluated under several conditions of single-phase pulse width modulation inverter excitation, and the results show that the proportion of loss by ON-voltages is up to around 10% depending on inverter excitation parameter: fundamental frequency, carrier frequency, modulation index, and magnetic flux density. [ABSTRACT FROM PUBLISHER]

This paper presents the simple analytical modeling for switched flux memory machine to provide in-depth insight into its working mechanism. The analytical approach is based on the slotless open-circuit air-gap flux density and the slotted air-gap relative permeance calculations for a doubly salient structure. In addition, due to low coercivity and highly nonlinear hysteresis curve at the second quadrant, the piecewise and virtual-linear hysteresis models of AlNiCo permanent magnet (PM) are presented to determine the PM working point. This combined analytical solution allows rapid calculation of several electromagnetic characteristics, e.g., air-gap flux density and back electromotive force. The effectiveness of the analytical method is validated by both finite-element results and measurements. [ABSTRACT FROM AUTHOR]

Increasing the silicon content in non-grain-oriented (NO) electrical steel sheets is known to decrease iron loss by changing electrical resistivity and magnetostriction behavior. However, few studies on the effect of high silicon contents in grain-oriented (GO) electrical steel have been reported. One of the major differences in the iron loss of GO and NO is that excess eddy current loss, which has a strong relationship with the magnetic domain structure, is more dominant in total iron loss in GO. In this paper, high silicon GO was prepared by the CVD siliconizing method, which has the advantage that the silicon content can be changed without changing the crystal grain size and crystallographic texture of the specimen. It was found that iron loss was reduced as the silicon content was increased, and 6.5 mass% silicon steel showed about half the hysteresis loss of conventional 3 mass% silicon steel, but the eddy current loss in 6.5 mass% silicon steel was equivalent to or slightly larger than that in 3 mass% silicon steel. Magnetic domain observation and calculations suggested that this difference was a result of coarsening of the magnetic domains in the high silicon steel. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new metal bonding method using a ceramic precursor (zirconium butoxide or titanium tetraisopropoxide) or a ceramic nano powder. Magnetic hysteresis curves of the bonded specimen did not change significantly after bonding in terms of the maximum magnetic field strength, the coercive force, and the residual magnetization. Iron loss of the specimen bonded using titanium tetraisopropoxide at 50 Hz increased by just 2.5%. The maximum shear strength per unit area was 0.29 N/mm2. [ABSTRACT FROM PUBLISHER]

This paper presents measured results of the 2-D vector magnetic characteristics of ultra-thin electrical steel sheets for high-efficiency high-speed motors. Generally, Non-oriented electrical steel sheets with 0.2–0.5 mm of thickness are used for motor cores. However, their thicknesses are not appropriate to use for cores of high-speed motors. We newly developed “Ultra-thin electrical steel sheet” with 0.08 mm of thickness to reduce the core loss of high-speed motors. The magnetic characteristics of the Ultra-thin electrical steel sheets are almost equal to NO (35A300) under exciting frequency of 50 Hz. Since the thickness of the steel sheet is very thin as 0.08 mm, eddy currents are hardly generated under high frequency. As the result, it was confirmed that the iron loss was decreased by 53% when we compare the iron loss of the motor used ultra-thin electrical steel sheets (0.08 mm) to that of the motor used conventional electrical steel sheets (0.35 mm) under the condition of 10 000 rpm. [ABSTRACT FROM AUTHOR]

Soft magnetic composites using metallic magnetic powders have extensively been investigated for the application to mobile electromagnetic devices, particularly motor cores. These metal powders are strongly required to be insulated from one another for low eddy-current losses. In addition, the insulation layer of the powders should possess high thermal stability for low hysteresis losses. Despite poor thermal stability, the iron phosphate coating on iron powders is still widely used because of a well-established technology. In this paper, we focused on the development of manganese phosphate coating on iron powders to overcome the low thermal stability of iron phosphate. It was shown that manganese phosphate insulation layers were thermally stable up to 600 °C. The core loss of composites with manganese phosphate-coated powders annealed at 600 °C measured 35.67 W/kg and the eddy-current loss 5.65 W/kg, indicating that excellent insulation coating layers were formed. [ABSTRACT FROM AUTHOR]

This paper presents the extension of two 1-D lamination models with magnetic hysteresis to reproduce dynamic hysteresis loops and power loss in grain-oriented (GO) electrical steels. For this purpose, the concept of magnetic viscosity is introduced in the model equations. The applicability and accuracy are demonstrated by means of two GO steels of different thicknesses at magnetizing frequencies up to 1000 Hz. Advantages and limits of the classical approach with and without viscosity and comparisons to measured data are discussed in detail. [ABSTRACT FROM AUTHOR]

In this paper, the temperature dependencies of iron loss under different flux densities, frequencies, and dc bias flux densities are systematically investigated. The temperature dependence of the hysteresis loss varies significantly with the dc bias flux density while that of the eddy current loss is independent of the dc bias flux density. Based on these different characteristics of the hysteresis and the eddy current iron losses, an improved iron loss model is developed. The temperature dependence of iron loss under dc bias condition can be considered by utilizing the improved iron loss model. The developed iron loss model is validated by both tests on laminations and an electrical machine. [ABSTRACT FROM AUTHOR]

The more electric engine concept considers the electric motor-generators included inside aircraft reactors. Because of the environment characteristics, the problem of reducing the losses in these machines becomes crucial. For such a purpose, this paper focuses on the magnetic losses, analyzing a small (10 kW) 12-phase induction motor-generator prototype through a validated numerical approach. We demonstrate that, with respect to the more traditional Fe-Si rotor core, the use of a Fe-Co alloy in the rotor reduces the total losses of up to 1%, and specifically the iron losses up to 7%, while increasing the generated electrical power up to 3%. [ABSTRACT FROM AUTHOR]

Consideration of a fully coupled lamination model with eddy currents and magnetic hysteresis in standard finite-element (FE) models is prohibitively expensive in terms of implementation effort, memory requirements, and computation time. Instead, this paper utilizes an algebraic approximation of the lamination model as a conventional constitutive relationship in (2-D) FE simulations of electrical machines. The TEAM problem 32, that is a test case for validating 2-D magnetic field analysis codes, which account for magnetic hysteresis, serves as a validation example. Extraction of the parameters of the parametric model and comparison with results using the fully coupled lamination model are presented. This pragmatic approach turns out to be quite accurate and efficient. [ABSTRACT FROM AUTHOR]