Iron Loss Model Research Articles

Anisotropic Models of Nonlinear Magnetic Behavior Laws for Finite Element Modeling of Iron Losses in a Toroidal Core

Anisotropic Models of Nonlinear Magnetic Behavior Laws for Finite Element Modeling of Iron Losses in a Toroidal Core

Research on the Material Characteristics and Loss Calculation Method of Cryogenic Permanent Magnet Motor Stator for LNG Pump

This paper explores the applicability of cryogenic permanent magnet motor stator materials for LNG pumps. First, this study selected four kinds of silicon steel sheets for motor stators tested at room temperature and ultra-low temperature and obtained the magnetization characteristics and loss characteristics of the four silicon steel sheets at room temperature and ultra-low temperature. Then, through a comparative analysis of experimental data, the applicability of silicon steel sheet material in an ultra-low-temperature environment was verified. Finally, the improved methods of the basic iron loss model of silicon steel sheets and the basic iron loss model of motors were proposed, and the accuracy and feasibility of the improved models were verified.

Design and Optimization of External Rotor Consequent Pole Permanent Magnet Motor with Low Iron Loss and Low Torque Ripple

To reduce the iron loss and torque ripple of an external rotor consequent pole (ERCP) motor used in an electric vehicle air-conditioning compressor, the magnetic pole structure of the motor was improved, and an unequal piecewise consequent pole (CP) structure was designed. The performance of the motor is optimized by reducing the harmonic content in the air gap flux density and reducing the iron saturation degree of the motor. The designed CP structure can significantly reduce the iron loss and torque ripple of the motor. Based on the Taguchi method, the optimal size parameters of the unequal piecewise CP structure are determined, and the final optimization design scheme is obtained. The results of finite element simulation and high-precision iron loss model show the following: compared with the original motor, the iron loss and torque ripple of the motor with the final optimized design scheme are significantly reduced.

Iron loss calculation model of high‐voltage multi‐pole asynchronous motors considering high harmonic flux density

AbstractA variable coefficient segmented iron loss calculation model is proposed for high‐voltage multi‐pole asynchronous motors, which fully considers the influence of high‐order harmonic magnetic density on such motors. This model introduces additional hysteresis loss, improved eddy current loss coefficients, and rotation magnetisation coefficients to account for changes in losses due to small hysteresis loops and skin effect, as well as rotation magnetisation losses. A 710 kW 10‐pole asynchronous motor is used as the research object. A full‐domain iron loss calculation model considering stator and rotor tooth top surface losses is developed. The model can be used to accurately calculate the overall and local harmonic iron losses in the stator and rotor cores of high‐voltage multi‐pole asynchronous motors. And quantitatively analyse the distribution pattern of any harmonic iron loss at any location in the motor core. It realises the refinement calculation and analysis of iron losses in the whole domain of high‐voltage multi‐pole asynchronous motor. Finally, no‐load and load tests were conducted on the 710 kW 10‐pole asynchronous motor. The iron losses of the 710 kW 10‐pole asynchronous motor at no load and load are calculated using the above mentioned model and the classical trinomial constant factor model. The results are compared with the measured iron loss values. It is proved that the iron loss model is more accurate in calculating the iron loss of high‐voltage multi‐pole asynchronous motor. The result helps researchers to calculate the iron loss distribution of high voltage motors more accurately. Thus, the design and operating parameters of the motor can be optimised to improve the efficiency and performance of the motor. It provides the necessary technical support and key basis for the reduction of loss and energy saving of high‐voltage motors and the optimisation of their core structure.

Loss parameter identification of a welded ring core lamination of NO‐electrical steel

AbstractLamination packaging processes such as welding lead to a significant material degradation of non‐oriented (NO) electrical steel sheets. Increase in iron loss and decrease in permeability are the results of the deterioration. For an efficient modeling of a drive train, the accurate parameterization of the iron loss is of upmost importance. For this reason, the iron loss model is expanded to include the influences of welding procedure. Its influence can be classified into changes in the grain size diameter and residual stresses . In this study, a locally varying iron loss model for the simulation of effects of weld‐packaging on the electromagnetic properties of non‐oriented (NO) electrical steel sheets is presented. Packaging technologies such as interlocking, welding, clinching and gluing are typically utilized for the manufacturing of electric steel stacks of electric machines. Understanding the micro‐structural changes due to the macro‐structural degradation accruing to weld‐packaging helps in the accurate understanding of its influence on the performance and achievable range of the electric vehicle. Five (5) electric steel probes are annealed for the modeling of the local varying iron loss model at five different temperatures and electromagnetically measured to determine its magnetization and loss values. This will help in determining the grain size dependency of the different loss parameters. The annealed probes are measured under mechanical stresses showing also the residual stress dependency.

Enhanced Efficiency in Permanent Magnet Synchronous Motor Drive Systems with MEPA Control Based on an Improved Iron Loss Model

This paper investigates the efficiency optimization problem in the drive system of Permanent Magnet Synchronous Motors (PMSM) based on the iron loss resistance model. Initially, an efficiency calculation method is proposed, utilizing the direct current (DC) side power based on the iron loss motor model as the input power. This approach determines the system’s input power by measuring DC side voltage and current, accounting for the impacts of temperature, magnetic saturation, and inverter nonlinearity. It avoids the need for intricate nonlinear loss modeling of the inverter, thereby simplifying the computational requirements for system efficiency. Simultaneously, the d-q axis equivalent equations based on the iron loss motor model are employed to calculate the system’s output power, enhancing the accuracy of the system efficiency calculation. An improved discrete gradient descent algorithm is presented based on this system efficiency calculation model, accelerating the search for the optimal current angle and improving its accuracy. In comparison to existing methods, this approach exhibits adaptive step size and provides more precise and higher efficiency calculations, resulting in faster search speeds. Experimental and simulation evaluations are conducted to assess the effectiveness of the proposed methods.

Energy-saving starting method of electric motor based on the battery-accumulator hybrid drive

The series electro-hydraulic hybrid powertrain has advantages in improving the dynamic characteristics and increasing the cruising range of battery rail vehicles. In order to reduce the large peak starting current of electric motor, an energy-saving starting method is proposed, which is using the hydraulic pump/motor to reversely drive the electric motor to restart at a speed, based on the energy reverse transfer characteristics between electric motor and hydraulic pump/motor. Firstly, the principle of restarting the electric motor at a speed is proposed based on the designed EH3. Then, PID is adopted to control the starting of electric motor which is driven by hydraulic powertrain. And a speed sensorless control algorithm is designed to control the restarting at a speed. Finally, aiming at the problem that the traditional simulation models of electro-hydraulic hybrid powertrain components are too simple and ideal. The estimation model of battery and SOC, dynamic efficiency model of hydraulic motor and dynamic iron loss model of PMSM are improved and optimized to improve the accuracy of powertrain simulation. The results both of co-simulation and experiments shows that the starting current can be reduced by 69.36 % at most and 64.91 % of battery consumption can be saved by restarting the electric motor at a speed.

Repeatability of Tests for Validation of Iron Loss Models in Electrical Machines

Repeatability of Tests for Validation of Iron Loss Models in Electrical Machines

Iron Loss Calculation Methods for Numerical Analysis of 3D-Printed Rotating Machines: A Review

Three-dimensional printing is a promising technology that offers increased freedom to create topologically optimised electrical machine designs with a much smaller layer thickness achievable with the current, laminated steel-sheet-based technology. These composite materials have promising magnetic behaviour, which can be competitive with the current magnetic materials. Accurately calculating the iron losses is challenging due to magnetic steels’ highly nonlinear hysteretic behaviour. Many numerical methodologies have been developed and applied in FEM-based simulations from the first introduced Steinmetz formulae. However, these old curve-fitting-based iron loss models are still actively used in modern finite-element solvers due to their simplicity and high computational demand for more-accurate mathematical methods, such as Preisach- or Jiles–Atherton-model-based calculations. In the case of 3D-printed electrical machines, where the printed material can have a strongly anisotropic behaviour and it is hard to define a standardised measurement, the applicability of the curve-fitting-based iron loss methodologies is limited. The following paper proposes an overview of the current problems and solutions for iron loss calculation and measurement methodologies and discusses their applicability in designing and optimising 3D-printed electrical machines.

Harmonic Injection Strategy Considering Multiplane Iron Loss Impact With Optimal Magnetizing Flux Distribution for Multiphase Induction Machines

Lagging orientation error detuning induced by iron losses for multi-planes of multiphase IM under non-sinusoidal supply control triggers error in determination of calculated harmonic, fundamental air-gap flux advance angles and harmonic slip frequency. This in-turn leads to inaccurate harmonic injected currents, which are dependent on harmonic multiple of frequency for the corresponding plane with respect to fundamental plane frequency. This paper proposes the novel harmonic injection strategy considering the detuned impact of iron losses by keeping in view the complete iron loss modeling for both harmonic magnetizing flux orientation control (MFOC) and fundamental rotor flux orientation control (RFOC) planes. Furthermore, satisfaction of complete optimal flux distribution constraints for multiphase IM are taken into account which results in preserving optimal flux patterns throughout the mechanical loading particularly at low and medium load conditions. Contrary to other traditional orientation schemes, this paper adopts the MFOC and RFOC for harmonic and fundamental plane respectively for acquiring the aligned and synchronized control of harmonic and fundamental air-gap flux distribution. Detailed experimental results incorporating seven phase induction machine as prototype are utilized to evaluate the harmonic injected currents, advance angles, slip frequencies and induced EMF waveforms which validate the effectiveness of proposed scheme.

Analysis of Core Loss Characteristics of Linear Phase-Shifting Transformer

Linear phase-shifting transformer, as a new type of phase-shifting transformer, has the advantages of shifting phase at any angle, good expansibility, and easy modularization compared with the traditional core column phase-shifting transformer. To calculate the output performance such as the efficiency of linear phase-shifting transformer, the loss of linear phase-shifting transformer should be studied. The loss of linear phase-shifting transformer includes copper loss and core loss. Among them, the core loss has an important impact on linear phase-shifting transformer performance parameters such as efficiency and temperature rise, but there is a lack of relevant research at present. In this paper, based on the traditional separation model of ferromagnetic materials, a calculation method for linear phase-shifting transformer core loss is proposed. In this method, the loss coefficient of the linear phase-shifting transformer iron loss model is calculated by the least square method based on the calculation and analysis of the magnetic field law of the core by the time-step finite element method, and the loss coefficient is further modified by considering the influence of local hysteresis loop, non-sinusoidal magnetic field, and harmonic magnetic field. The linear phase-shifting transformer model based on finite element field-road coupling simulation is established, a low-power experimental prototype is designed, and a multi-stack inverter system platform is built. The theoretical calculation is verified by simulation and experiment. Simulation and experimental results demonstrate the accuracy of the core loss calculation method presented in this paper.

Efficiency improvement of a high-speed permanent magnet excited synchronous machine by the use of spot-welding as lamination packaging technology

In this paper, an efficiency improvement of a high-speed permanent magnet excited synchronous machine (PMSM) by the use of spot-welding as lamination packaging technology is realized. Welding, interlocking, clinching and gluing are typical technologies to manufacture electrical steel stacks of electrical machines. However, these processes deteriorate the magnetic properties of the steel sheets, thereby decreasing the overall efficiency of the machine. Variations of line-welding (six, eight, twelve, thirty two and forty) line welds and spot-welding procedure is performed and analyzed. A semi-physical iron loss separation approach is used to extract the IEM iron loss model (Eggers et al., IEEE Transactions on Magnetics 48(11) (2012), 3021–3024). These parameters are utilized during the finite element simulation to calculate the effective iron loss (efficiency) of the machine while using each joining procedure. A low speed, high-speed and WLTC-c3 driving cycle is exemplarily used to analyze the effects of each procedure on the machine efficiency at the different operating conditions.

Stress-Dependent Magnetic Equivalent Circuit for Modeling Welding Effects in Electrical Steel Laminations

Welding has a severe impact on the efficiency of electrical machines. The heat added during the welding process affects the microstructure of the material and causes residual stress. This results in local degradation of the magnetic permeability and facilitates additional iron losses in the machine core. With the purpose of modeling and simulating welding effects in electric machines, this paper proposes a stress-dependent magnetic equivalent circuit (MEC) model for welded non-grain-oriented electrical steel laminations. A modified iron loss model is proposed to accommodate these welding effects. Furthermore, the proposed MEC model is applied to a M270-35A stator core as a case study. It was demonstrated that the core losses increase by 25% when four welding joints are applied. With a limited number of magnetic measurements on a welded and unwelded core, the model can be fully parametrized. Finally, the model was successfully validated on a core with eight welding seams at 100 Hz. The proposed model can be integrated into the design of electric machines to consider the welding effects.

Improvement of core loss model under AC–DC hybrid excitation and verification based on TEAM P21 extended model

HVDC (High Voltage Direct Current) transmission equipment generally works under AC–DC hybrid excitation (with both DC-bias components and harmonics), increasing the loss of magnetic components and even causing local overheating. In order to study the influence of AC–DC hybrid excitation on the performance of magnetic materials, the loss properties of electrical silicon steel under AC–DC hybrid excitation are measured and modelled. This paper improves the iron loss model based on the Bertotti loss model by introducing a new term caused by DC bias. In addition, the improved loss model is combined with the transient loss model, and the iron loss calculation is performed based on the results of the TEAM P21 extended model. The comparison between the calculated and measured loss shows that the improved loss model is more accurate than the traditional one.

New formulation of Loss-Surface Model for accurate iron loss modeling at extreme flux density and flux variation: Experimental analysis and test on a high-speed PMSM

The Loss-Surface (LS) model, commonly used for the prediction of iron losses in electrical machines, is reformulated for better accuracy and reliability when it is extrapolated beyond the parametric identification region. First, the dynamic hysteresis behaviors of typical soft magnetic materials are analyzed by both measurements and FE simulations. They are then described by the LS model using different mathematical formulations. The most relevant one, which requires 14 parameters to reproduce and extrapolate any loss surface, will be presented in this paper. The newly reformulated LS model is tested, in the last part, to estimate the iron losses of intrinsic measurements as well as of an electrical machine. In the first case, the results obtained of four different materials are generally within 5% error. And in the latter case of a high speed permanent magnet synchronous motor, by performing a study on the effects of manufacturing methods (punching and assemble) with respect to the iron losses, it is shown that the LS model provides an estimation with around 10% of deviation.

Loss Parameter Identification After Cutting for Different Non-Oriented Electrical Steel Grades

The magnetic properties of nonoriented (NO) electrical steel sheet are sensitive to industrial cutting processes. Decreased operation point efficiency and an increase in local iron loss in the magnetic circuit of an electrical machine are the consequences. During the design of electrical machines, the cut-edge effect and its consequences can only be considered and assessed, if the effect is locally modeled. In fact, the cut-edge effect is often neglected as standardized magnetic characterization is performed, where the sheet material is measured on an Epstein frame or single sheet tester (SST) and gentle sample preparation is specified. In order to parameterize a local material model, a large number of samples and their detailed magnetic characterization at various magnetizing frequencies are necessary. In this article, the loss parameters of nine different industrial NO electrical steels are identified and analyzed in order to study the course of the parameters and possible interrelation with material properties. The sheet thickness, alloying content of silicon and aluminum, and grain sizes are considered as they are the dominant influences on the iron loss from the material side. The presented results help to increase the understanding of the cut-edge effect and its consequences on the iron loss modeling. Furthermore, they help to identify possibilities to decrease the measurement effort significantly.

Accurate Calculation of Iron Loss of High-Temperature and High-Speed Permanent Magnet Synchronous Generator under the Conditions of SVPWM Modulation

The high-temperature and high-speed permanent magnet synchronous generator (HTHSPMSG) is the core component ensuring the efficient and safe operation of the high-speed aircraft power supply system. At present, the existing iron loss model fails to meet the requirements for the precise calculation of the iron loss of HTHSPMSG under high-temperature and high-frequency conditions. In this paper, a 40 kW, 18,000 rpm HTHSPMSG is used to study the accurate calculation of iron loss at an ambient temperature of 350 °C. Considering the influence of high temperature and high frequency on the loss and performance of electromagnetic materials, a test platform for the loss performance of the magnetic core materials is established. Then, according to the loss performance of the electromagnetic material, the corresponding iron loss coefficient is fitted by the variable coefficient iron loss separation model. In addition, the digital twin field-circuit co-simulation method is proposed to guarantee the accuracy of the iron loss calculation. Then, the influence of carrier frequencies and modulation ratios on the iron loss characteristics of the HTHSPMSG under the conditions of SVPWM modulation is studied. Lastly, the effectiveness of the proposed method is verified by the experimental results, which provide a reference for the accurate analysis of iron loss of the same type of HTHSPMSG.

Influence of stator segmentation on iron losses in PMSMs for traction applications

PurposeThis paper presents a comparative study of different stator-segmentation topologies of a permanent magnet synchronous machine (PMSM) used in traction drives and their effect on iron losses. Using stator segmentation allows one to achieve more significant copper fill factors, resulting in increased power densities and efficiencies. The segmentation of the stators creates additional air gaps and changes the soft magnetic material’s material properties due to the cut edge effect. The aim of this paper is to present an in-depth analysis of the influence of stator segmentation on iron losses. The main goal was to compare various segmentation methods under equal excitation conditions in terms of their influence on iron loss.Design/methodology/approachA transient finite element method analysis combined with an extended iron-loss model was used to evaluate discussed effects on the stator’s iron losses. The workflow to obtain a homogenized airgap length accounting for cut edge effects was established.FindingsThe paper concludes that the segmentation in most cases slightly decreases the iron losses in the stator because of the overall reduced magnetic flux density B due to the additional air gaps in the magnetic circuit. An increase of the individual components, as well as total power loss, was observed in the Pole Chain segmentation design. In general, segmentation did not change the total iron losses significantly. However, different segmentation methods resulted in the different distortion of the magnetic field and, consequently, in different iron loss compositions. The analysed segmentation methods exhibited different iron loss behaviour with respect to the operation points of the machine. The final finding is that analysed stator segmentations had a negligible influence on the total iron loss. Therefore, applying segmentation is an adequate measure to improve PMSMs as it enables, e.g. increase of the winding fill factor or simplifying the assembly processes, etc.Originality/valueThe influence of stator segmentation on iron losses was analysed. An in-depth evaluation was performed to determine how the discussed changes influence the individual iron loss components. A workflow was developed to achieve a computationally cheap homogenized model.

Iron Loss Modeling of Grain-Oriented Electrical Steels in FEM Simulation Environment

Regularly used in power transformers, grain-oriented (GO) steels are also usually chosen for the manufacturing of the stator cores of hydro generator and turbogenerator. These steels are renowned for their high magnetic performances in the rolling direction (RD) (high permeability and low magnetic losses). Nevertheless, in a turbogenerator where GO steels are employed to reduce the size of the stator core, the magnetic flux flows through several successive directions within the plane of the steel. So, the anisotropic behavior of the GO steel has to be considered in the design step of the related devices in order to improve their energy efficiency as well as their diagnosis based on modeling. In this article, an anisotropic phenomenological iron loss model, quite recently developed, has been studied and successfully implemented in a finite element method (FEM) simulation environment. The implementation has been validated against experimental data achieved on an industrial conventional GO grade typically used in turbogenerators. The results show a good agreement of the computational results with the experiments for both quasi-static and dynamic regimes.

Simulation of iron losses in induction machines using an iron loss model for rotating magnetization loci in no electrical steel

PurposeVarious iron loss models can be used for the simulation of electrical machines. In particular, the effect of rotating magnetic flux density at certain geometric locations in a machine is often neglected by conventional iron loss models. The purpose of this paper is to compare the adapted IEM loss model for rotational magnetization that is developed within the context of this work with other existing models in the framework of a finite element simulation of an exemplary induction machine.Design/methodology/approachIn this paper, an adapted IEM loss model for rotational magnetization, developed within the context of the paper, is implemented in a finite element method simulation and used to calculate the iron losses of an exemplary induction machine. The resulting iron losses are compared with the iron losses simulated using three other already existing iron loss models that do not consider the effects of rotational flux densities. The used iron loss models are the modified Bertotti model, the IEM-5 parameter model and a dynamic core loss model. For the analysis, different operating points and different locations within the machine are examined, leading to the analysis of different shapes and amplitudes of the flux density curves.FindingsThe modified Bertotti model, the IEM-5 parameter model and the dynamic core loss model underestimate the hysteresis and excess losses in locations of rotational magnetizations and low-flux densities, while they overestimate the losses for rotational magnetization and high-flux densities. The error is reduced by the adapted IEM loss model for rotational magnetization. Furthermore, it is shown that the dynamic core loss model results in significant higher hysteresis losses for magnetizations with a high amount of harmonics.Originality/valueThe simulation results show that the adapted IEM loss model for rotational magnetization provides very similar results to existing iron loss models in the case of unidirectional magnetization. Furthermore, it is able to reproduce the effects of rotational flux densities on iron losses within a machine simulation.