Core Loss Model Research Articles

Physics-Inspired Multimodal Feature Fusion Cascaded Networks for Data-Driven Magnetic Core Loss Modeling

Physics-Inspired Multimodal Feature Fusion Cascaded Networks for Data-Driven Magnetic Core Loss Modeling

Evaluating the thermal stability of an interior permanent magnet synchronous machine through iterative multi‐physics simulation

AbstractThis paper investigates the thermal operating capability of an interior permanent magnet synchronous machine. An iterative workflow is presented, combining electromagnetic modeling, control, power‐loss modeling, and thermal modeling to identify maximum thermal stable operating points. Special attention is given to the critical temperatures of winding and permanent magnets. A nonlinear reduced order model based on finite element method model was used to simulate the system, including an inverter model with space vector pulse width modulation in combination with field‐oriented control. Furthermore, an advanced iron core loss model and thermal lumped parameter model were employed. The presented approach allows for evaluating losses and their impact on steady‐state temperatures. The obtained results highlight the significant influence of space vector pulse width modulation on iron core losses and the importance of considering both advanced power‐loss models and adequate thermal models when analyzing the machine's thermal state. This research emphasizes the concept of a thermally stable envelope, providing a comprehensive understanding of the thermal boundaries under various operating conditions.

Compact Switched-Inductor Power Supplies: Design Optimization with Second-Order Core Loss Model

Expressing switched-inductor converter losses simply as a function of design variables is key for designers. Power losses in switched-inductor power supplies are varied in nature, and optimization schemes in the literature fail to account for all of them. Available core loss models are mostly empirical or rely on measurements or variables beyond the reach of power supply designers. Specifically, a simple core loss model is missing. This work offers complete design optimization of switched-inductor power supplies with a quadratic model of core loss that relies solely on design variables known to the designers—inductance and switching frequency (or inductor peak current). This model alleviates the burden of performing complex measurements to characterize the inductor—measurements that, moreover, require geometric data about the core, such as its size, which are often not disclosed by the manufacturer. Predicted minimum losses without approximation are within 3.2% of measured minimum losses, and predicted minimum losses with approximation are within 2.2% of measured minimum losses.

Research on loss characteristic of soft magnetic composites under nonsinusoidal excitations with DC bias field

Choosing a suitable core loss model and accurately predicting energy loss are crucial in designing magnetic devices with high efficiency based on soft magnetic composites (SMCs). In this work, FeSiAl and FeSi SMCs with a uniform insulating layer were fabricated by a phosphating process. The effects of excitation waveform and DC bias field on core loss have been investigated in depth. The results show that different remagnetization rates of SMC under ideal sinusoidal and square waves result in different core losses at the same frequency and flux density. The improved general Steinmetz equation and the modified Steinmetz equation were shown to be suitable for calculating core loss under square excitation waves without DC bias field. When the DC bias field is applied, the core loss of FeSiAl and FeSi SMCs was found to increase significantly due to the magnetization state gradually approaching saturation. Interestingly, the variation tendency of core loss can be accurately predicted using the waveform coefficient Steinmetz equation under square excitation conditions with a DC bias environment. This work not only provides deep insights into core loss under different excitation waveforms and DC bias fields but also determines the application scope of different core loss models.

Hysteresis loss in Brushless Doubly Fed Induction Machines

Brushless doubly fed machine (BDFM) is a potential for future wind energy generation, due to its lower maintenance costs and higher reliability than conventional doubly fed systems. While efficiency and design optimization of the machine has become critical issues recently, no analytical core loss model is investigated in the literature. Furthermore, core loss modeling is different from conventional induction machines, because of double frequency excitation of the machine. In this paper, a dynamical system is used for modeling of hysteretic behavior of iron core, and hysteresis losses of BDFM are analyzed and modeled mathematically. The flux waveforms of BDFM are assumed pure double sine, as in wound rotor BDFM lower harmonic values than nested loop design exist.

A Review on the Empirical Core Loss Models for Symmetric Flux Waveforms

A Review on the Empirical Core Loss Models for Symmetric Flux Waveforms

A Physical Core-Loss Model for Laminated Magnetic Sheet Steels

A Physical Core-Loss Model for Laminated Magnetic Sheet Steels

Semi-Analytical Non-Linear Physical Model of Core Losses in Ferrite Ring Cores

Semi-Analytical Non-Linear Physical Model of Core Losses in Ferrite Ring Cores

Effect of Annealing Time on Texture Evolution of Fe–3.4 wt% Si Nonoriented Electrical Steel

Herein, the effect of annealing time on the texture evolution in Fe–3.4 wt% Si non‐oriented electrical steel is investigated. Strip samples are cast using a vacuum sampling method, which simulate the solidification conditions of an industrial twin roll thin strip casting (TRSC) process. As‐cast samples with different carbon and sulfur (C&S) levels are hot rolled (HR) with varying levels of hot deformation, cold rolled (CR) to 0.35 mm thickness, and then annealed at 1050 °C for different holding times (1, 6, 24 h). To Fe–3.4 wt% Si nonoriented electrical steel, the observed texture evolution can be divided into different stages as annealing time is increased from 1 to 24 h. With increasing annealing time, the fraction of Goss texture decreases initially and then increases again through the consumption of grains with other textures. With additional time, a decrease of pinning force due to precipitate coarsening results in normal grain growth, resulting in an increase of grain size. In this step, Cube grains can form from rotated Goss grains. A model for core loss is presented and used to explain the core loss results.

Core Loss Equivalent Resistance Modeling of Small- and Medium-Sized Converter-Fed Induction Motors Considering Supply and Spatial Harmonics

In order to estimate the core loss resistance of converter-fed induction motor accurately and efficiently, an analytical piecewise variable-coefficient core loss model is proposed. By introducing two voltage harmonics related coefficients, the influence of converter harmonics on core loss is simply and effectively considered. In addition, the surface and pulse loss caused by slot harmonics and the additional harmonic core loss caused by harmonic magnetic potential of stator winding under load condition are also considered. Based on the proposed model, an advanced core loss equivalent resistance model of converter-fed induction motor considering supply and spatial harmonics is proposed. The effectiveness of the proposed model is validated by comparisons with the measured core losses of 5.5 kW induction motor under no-load condition. In addition, compared with the finite element method under load condition, the proposed analytical model reduces the computational time significantly while maintaining high accuracy.

Review of Hysteresis Models for Magnetic Materials

There are several models for magnetic hysteresis. Their key purposes are to model magnetization curves with a history dependence to achieve hysteresis cycles without a frequency dependence. There are different approaches to handling history dependence. The two main categories are Duhem-type models and Preisach-type models. Duhem models handle it via a simple directional dependence on the flux rate, without a proper memory. While the Preisach type model handles it via memory of the point where the direction of the flux rate is changed. The most common Duhem model is the phenomenological Jiles–Atherton model, with examples of other models including the Coleman–Hodgdon model and the Tellinen model. Examples of Preisach type models are the classical Preisach model and the Prandtl–Ishlinskii model, although there are also many other models with adoptions of a similar history dependence. Hysteresis is by definition rate-independent, and thereby not dependent on the speed of the alternating flux density. An additional rate dependence is still important and often included in many dynamic hysteresis models. The Chua model is common for modeling non-linear dynamic magnetization curves; however, it does not define classical hysteresis. Other similar adoptions also exist that combine hysteresis modeling with eddy current modeling, similar to how frequency dependence is included in core loss modeling. Most models are made for scalar values of alternating fields, but there are also several models with vector generalizations that also consider three-dimensional directions.

Application analysis of self-bonded electrical steel sheet in high power density PMSM for all-electric aircraft

Driving motor for all-electric aircraft (AEA) needs high power density and high torque density, resulting in the magnetic load and electrical load of driving motor in a limit state. Therefore, it is important to analyze the accurate calculation of core loss and the technology of loss suppression. Firstly, B35A230 self-bonded electrical steel sheet is used as core, which can reduce core loss caused by machining process. Then the ratio-loss curves of B35A230 at different frequencies and different flux densities are measured by Epstein frame and ring sample method, and the increment of core loss after machining is obtained, and the influence of axial welding paths on stator core loss is analyzed. According to experimental results, Based on the classical stator core loss model, machining factors are considered to improve the accuracy of stator core loss, and a core loss model is adopted to improve accuracy, considering processing factor, alternating and rotating magnetization modes and harmonic magnetic field. Finally, an outer rotor SPMSM for AEA is designed and manufactured, and the no-load loss is tested experimentally, which verified that the self-bonded electrical steel sheet has certain advantages in high power density driving motor.

Designing High-Power-Density Electric Motors for Electric Vehicles with Advanced Magnetic Materials

As we face issues of fossil fuel depletion and environmental pollution, it is becoming increasingly important to transition towards clean renewable energies and electric vehicles (EVs). However, designing electric motors with high power density for EVs can be challenging due to space and weight constraints, as well as issues related to power loss and temperature rise. In order to overcome these challenges, a significant amount of research has been conducted on designing high-power-density electric motors with advanced materials, improved physical and mathematical modeling of materials and the motor system, and system-level multidisciplinary optimization of the entire drive system. These technologies aim to achieve high reliability and optimal performance at the system level. This paper provides an overview of the key technologies for designing high-power-density electric motors for EVs with high reliability and system-level optimal performance, with the focus on advanced magnetic materials and the proper modeling of core losses under two-dimensional or three-dimensional vectorial magnetizations. This paper will also discuss the major challenges associated with designing these motors and the possible future research directions in the field.

Research on Deterioration Mechanism and High-Precision Modelling of the Core Loss for Amorphous Alloys after Wire-Cut Electric Discharge Machining

Amorphous alloys (AAs) have the advantage of low core loss. Thus, they can be used in high-speed motor applications. However, compared with the nominal performances, the performance of the wire-cut electric discharge machine (W-EDM)-processed AA iron core changes significantly, which limits its popularization. This paper focuses on the performance degradation mechanism of the AA ribbon caused by W-EDM and establishes a modified core loss model after machining. First, a 308 × 15 mm ribbon-shaped AA sample machined by W-EDM was prepared. The characterization and analysis of the magnetic properties, phase, magnetic domain, nano-indentation, micro-morphology, and composition were carried out. In this paper, by analysing the variation in the magnetic domain distribution based on domain width and nano-mechanical properties, it is proposed that the performance degradation range of AA ribbons processed by W-EDM is within 1 mm from the edge. By comparing the microscopic morphology and chemical composition changes in the affected and the unaffected area, this paper presents a mechanism for the property deterioration of W-EDM-processed AA ribbons based on electrochemical corrosion. Finally, a modified loss model for W-EDM-processed AAs is established based on the division of the affected area. This model can significantly improve the accuracy of core loss estimation in the medium- and high-frequency bands commonly used in high-speed motors.

Electromagnetic Performance Prediction of an Induction Machine Using an Improved Permeance-Based Equivalent Circuit Model Considering the Frequency and B–H Curve Dependent Core Loss Branches

Equivalent circuit models (ECMs) are extensively used in the prediction of steady-state performance characteristics of electric machines due to its simplicity and ease of implementation. In this article, permeance-based ECM is developed and improved by incorporating the machine's nonlinearities, and magnetic saturation. A recursive core loss model as a function of air gap voltage, considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B–H</i> hysteresis, eddy current, excess loss coefficients, and Steinmetz factor is developed to improve the accuracy of the electromagnetic performance prediction. Furthermore, an adaptive restart genetic algorithm is used to improve the accuracy of the coefficients and Steinmetz factor prediction over a wide range of frequencies and flux densities for both the stator and rotor. Moreover, skin effect is incorporated in the eddy current core loss to accurately consider the impact of varying frequencies and loadings. Finally, the proposed permeance-based ECM's calculated torque, core loss, and efficiency are experimentally validated using a prototyped squirrel–cage traction induction machine at various speeds and loading conditions. Toward net-zero carbon emissions, transportation electrification is a significant step requiring high–speed traction motors for electric vehicle application. Therefore, an accurate ECM is proposed that can successfully capture the frequency-dependent effects in the prediction of core loss, torque, and efficiency.

Loss Modeling and Reluctance Quantifying of C-Type Amorphous Core for High-Frequency Inductors

The wound core with ultrathin magnetic strip is expected to improve the high-frequency performance of the electronic devices in efficiency and scale. However, the analysis of magnetic properties and calculation of the magnetic loss, including core loss and air-gap loss for cutting double C-type core, are complex and have not been entirely solved. In this article, the magnetic properties of a C-type amorphous core (AMCC0025) at different air-gap lengths are measured through a newly constructed tester. The measurement results are analyzed in detail, and the mechanism of magnetic loss influenced by the air gap is revealed by quantifying the reluctance of the C-type core. An accurate core loss model considering a fringing effect is derived, together with another additional loss model is realized by regression analysis. The evaluation results show that the average error for the partial total loss is less than 10%, and the average error for additional loss and core loss is within 5%. All errors meet the requirements of engineering calculation.

Core loss measurement and comparative analysis for soft magnetic materials under complex non-sinusoidal excitations

With the advancement of wide-bandgap power devices, the power electronics equipment is developing toward higher switching frequencies and more complex switching modes in recent years. Accurate prediction of the core loss for magnetic components has been emphasized as the excitations of magnetic materials varying depending on the operating mode of the power supplies. Therefore, this paper presents the results of an extensive core loss study performed on nanocrystalline alloy (FT-3KL), amorphous alloy (1K101) and ultra-thin oriented silicon steel (GT-50). Firstly, an automatic setup for core loss measurement of soft magnetic materials fed by a full-bridge inverter based on silicon carbide (SiC) MOSFET is proposed. Then, the effects of switching oscillations from the inverter and the characteristic parameters of complex non-sinusoidal excitations on the core loss are analyzed comparatively. The core loss shows different regular distributions with the change of each characteristic parameter of excitations respectively. However, the regular distributions will be influenced by the high-frequency switching oscillations, which makes the prediction of core loss more complicated. This paper can provide a reference for the development of high-precision core loss model and performance optimization of power electronics equipment.

A Review of Magnetic Core Materials, Core Loss Modeling and Measurements in High-Power High-Frequency Transformers

High-frequency transformers (HFTs) are the indispensable component in isolated high-power dc-dc converters which have been the basic building blocks for solid-state transformers. To ensure high efficiency, high power density and high reliability, careful selection, design, modeling and evaluation are necessary for the magnetic core of an HFT. However, due to the nonlinear characteristics and the complex physical mechanism, magnetic cores have always been regarded as the focus and difficulty. This paper systematically reviews magnetic core materials commonly used in HFTs, core loss modeling methods based on classical Steinmetz equation (SE), and advanced core loss measurement techniques. Pros and cons for the magnetic materials, modeling and measurement methods are comprehensively analyzed and summarized to provide a sufficient application insight.

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.

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.