Iron Loss Analysis Research Articles

Iron Loss and Temperature Rise Analysis of a Transformer Core Considering Vector Magnetic Hysteresis Characteristics under Direct Current Bias.

Direct current (DC) bias induced by the DC transmission and geomagnetically induced current is a critical factor in the abnormal operation of electrical equipment and is widely used in the field of power transmission and distribution system state evaluation. As the main affected component, the vector magnetization state of a transformer core under DC bias has rarely been studied, resulting in inaccurate transformer operation state estimations. In this paper, a dynamic vector hysteresis model that considers the impact of rotating and DC-biased fields is introduced into the numerical analysis to simulate the distribution of magnetic properties, iron loss and temperature of the transformer core model and a physical 110 kV single-phase autotransformer core. The maximum values of B, H and iron loss exist at the corners and T-joint of the core under rotating and DC-biased fields. The corresponding maximum value of the temperature increase is found in the main core limb area. The temperature rise of the 110 kV transformer core under various DC-biased conditions is measured and compared with the FEM (Finite Element Method) results of the proposed model and the model solely based on the magnetization curve B||H. The calculation error of the temperature rise obtained by the improved model is approximately 3.76-15.73% and is much less than the model solely based on magnetization curve B||H (approximately 50.71-66.92%).

Iron Loss Analysis of High-Speed AFPM Motor With Ultra-Thin Silicon Steel Considering Bending Stress

Iron Loss Analysis of High-Speed AFPM Motor With Ultra-Thin Silicon Steel Considering Bending Stress

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.

DESIGN OF THE PERMANENT MAGNET SYNCHRONOUS MOTOR USED IN ELECTRIC VEHICLES WITH THE HELP OF THE PARTICLE SWARM ALGORITHM AND ANSYS-MAXWELL

Performance and efficiency are among the most important parameters in electric motors. Improvements to the engine not only increase engine performance, but also affect production costs. Permanent Magnet Synchronous Motor (PMSM) is a motor widely used in electric vehicles with its high torque density, high efficiency and production advantages. In this study, 110 kW (Adjust-Speed Permanent Magnet Synchronous Motor) AS-PMSM was designed for electric vehicle applications. The results of ANSYS-Maxwell and Particle Swarm Optimization (PSO) algorithms and the calculations of the optimized design were compared in line with the obtained data. In the design study, theoretical calculations, PSO algorithm and finite element method (FEM) based ANSYS-Maxwell software were used. Based on these values, the computer aided design of the engine was carried out. First of all, the basic design and performance criteria of the engine were determined. Parameters of the motor such as torque ripple, iron loss, efficiency and electromagnetic analysis were analyzed and optimized with ANSYS-Maxwell. Then, electrical, magnetic and performance analyzes of the motor were made. How the engine performance changes with the methods used has been examined in detail. Efficiency values were determined under various operating conditions in engine performance studies. The validity of the improvement study and the verification of the design study were examined by comparing the ANSYS results with the PSO algorithm results. The analysis results showed that the designed electric motor met the desired power values and design performance criteria.

LLG方程式による直流ヒステリシス特性の計算精度に関する諸検討

Quantitative analysis of iron loss taking magnetic hysteresis behavior into account is essential to loss reduction in electric machines. In the previous research, a novel magnetic circuit model, which incorporates a play model and a Cauer circuit, was proposed. Besides, the play model can be derived from dc hysteresis loops calculated by a simplified Landau-Lifshitz-Gilbert (LLG) equation. However, this method cannot necessarily calculate dc hysteresis loops with high accuracy in all cases so that there is potential for further improvement in its calculation accuracy. Therefore, in this paper, the calculation accuracy of the simplified LLG equation is examined in detail under various conditions.

Iron loss analysis of magnetic bearing system considering magnetic-thermal coupling

When the magnetic bearing rotor is working, the iron loss concentration phenomenon may occur on the rotor journal, which will cause the temperature gradient on the rotor journal and thermal unbalance. In order to study the iron loss concentration phenomenon, a multi-physics simulation method considering the magnetic-thermal coupling is proposed. Using ANSYS Maxwell for modeling and finite element analysis to obtain the causes of iron loss concentration in magnetic bearing and the influence of different parameters on the size and distribution of iron loss; using COMSOL for magnetic-thermal coupling in magnetic bearing to obtain the influence of iron loss concentration on temperature distribution. The simulation results show that: because of the initial disturbance, the control effect of the magnetic bearing makes the magnetic field distribution on the circumference of the rotor journal uneven, resulting in the phenomenon of iron loss concentration; control current and bias current have significant influence on iron loss distribution, while bias current and speed have a significant influence on iron loss value; iron loss concentration will result in a temperature gradient on the rotor surface. The magnetic-thermal coupling finite element analysis is verified by the temperature rise detection experiment. It provides a theoretical basis and reference for the loss and thermal unbalance of magnetic bearing.

Preliminary analysis of eddy current and iron loss in magnetic gear in electric vehicle

The inclusion of a high energy density permanent magnet into magnetic gear improves the machine's torque density. However, it also contributes to eddy current loss, especially in a high-speed application such in electric vehicle. In this paper, the losses from eddy current and iron loss are investigated on concentric magnetic gear (CMG). Torque multiplier CMG is designed with 8/3 gear ratio for this study. Iron loss and eddy current loss are compared and discussed. Based on this study, eddy current loss contributes to almost 96% of the total loss. This finding is hoped to direct the researcher to focus more on reducing loss associated with eddy current loss.

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.

Iron Loss Analysis and Efficiency Calculation of Double Stator HTS Machine With Stationary Seal

This paper mainly analyzes the iron loss of a double stator high-temperature superconducting (HTS) machine with stationary seal and calculates its efficiency. Firstly, according to the field-modulation theory, the air-gap flux density harmonic components of the excitation magnetic field and armature-reaction magnetic field are derived. Secondly, the air-gap flux density harmonic components corresponding to the flux density harmonic components of iron core are derived, and the main iron core flux density harmonic components are confirmed and verified by finite element analysis (FEA). When using the semi-FEA method to calculate the iron loss, according to the analysis results of main core flux density harmonic components, the appropriate step-interval of the FEA is selected. In addition, according to the characteristics of the iron core flux density, this paper proposes an alternative method of iron core flux density, which greatly shortens the calculation time of semi-FEA method of iron loss calculation. Then, iron loss model with variable coefficients is used to calculate the iron loss of the machine, and the calculation results are compared with those of the FEA iron loss calculation method. Finally, other losses and efficiency of the machine are calculated.

Fractional-Slot PMSMs With One Coil Parallel Branches Made Phases—Part 2: Circulating Harmonic Current Rejection Potential

The paper is aimed at a class of fractional-slot permanent magnet- synchronous machines (FSPMSMs) equipped with phases made up of one coil parallel branches, with emphasis on their potential to reject the circulating harmonic currents. Following the identification and topological characterization of this class of machines treated in Part 1, the star of slots approach is extended to the investigation of their back-EMF harmonic content, and the possible resulting circulating harmonic currents. It is found that all identified candidates exhibit the potential to reject the circulating harmonic currents. A case study dedicated to a candidate equipped with three phases made up of six parallel branches of one coil each, is treated. Following an analysis of its back-EMF harmonic content, the torque-speed characteristic is analytically-predicted and validated by 2D finite element analysis and by experiments. The study is achieved by a special attention paid to the iron loss and thermal analysis.

Определение потерь в стали бесконтактного двигателя постоянного тока с использованием линейной аппроксимации импульсов напряжения

Analysis of iron loss of a BLDC motor is of particular interest at the design stage or when researching methods to improve energy efficiency. Most of the existing methods for determining losses in steel are based on the analysis of losses for individual harmonic components of induction with their subsequent summation. However, the application of these methods for various forms of voltage obtained at the output of the converter is incorrect due to the non-linearity of magnetic circuits. This paper proposes a method for determining steel losses of BLDC motor using a linear approximation of voltage pulses, which makes it possible to take into account the influence of the voltage shape on the magnitude of magnetic induction directly, without expansion into a Fourier series. The dependences of steel losses on the switching frequency for various values of the duty cycle, and on the rise time of voltage pulses are obtained. Comparison of the simulation results of the 5 kW BLDC Motor with the experimental data of the idling mode given by the manufacturer proved the adequacy of the considered method.

Fault Mechanism Analysis of Irreversible Demagnetization Due to the Dynamic Eccentricity of IPMSM for EV Traction

The dynamic eccentricity fault (DEF) of the interior permanent magnet synchronous motor (IPMSM) is mainly caused by external mechanical shock. In the case of DEF, an unbalanced magnetic force occurs because the length of the air gap is not constant. Noise and vibration of the motor occur due to unbalanced magnetic force. In addition, since the length of the air gap is not constant, the distribution of magnetic flux density is distorted, and iron loss is increased. As the iron loss increases, the temperature rises, and an irreversible demagnetization fault (IDF) of the permanent magnet occurs due to overheating. Therefore, in this paper, the fault mechanism of IDF due to DEF of IPMSM for electric vehicle (EV) traction is analyzed. Initially, the magnetic flux density and iron loss characteristics according to the healthy condition and DEF condition are analyzed using the finite element method (FEM). Then, the detailed iron loss analysis is performed based on the phase current waveform measured through the load test of the motor. Finally, the fault mechanism of IDF due to DEF was verified through an electric-axle load test on a manufactured motor having eccentricity.

Analysis and Verification of Traction Motor Iron Loss for Hybrid Electric Vehicles Based on Current Source Analysis Considering Inverter Switching Carrier Frequency

In this study, a current source analysis method considering the inverter switching frequency is proposed to improve the precision of loss analysis of a traction motor for a hybrid electric vehicle. Because the iron loss of the traction motor is sensitively influenced by input current fluctuations, the current source analysis using the actual current obtained from an inverter is the ideal method for accurate analysis. However, as the traction motor and inverter should be manufactured to obtain the real current, the traction motor is generally designed based on an ideal current source analysis. Our proposed method is an analytic technique that fits the loss of a traction motor similar to the actual loss by injecting harmonics of the same order of the inverter switching frequency into the ideal input current. Our method is compared with the analysis of the ideal current source to assess the difference in loss. In addition, a test motor was manufactured, and an efficiency test was conducted to compare the efficiency and verify the effectiveness of our method.

Iron loss analysis and calculation of high energy density permanent magnet machine

Abstract It is a research hotspot of electric propulsion system that a high energy density permanent magnet machine is used as its main power. In general, the power system of electric propulsion consists of batteries, inverters and high energy density permanent magnet machines and loads. Based on harmonic effect of PWM sine alternating current generated by inverter, iron loss model of high energy density permanent magnet machine is established under inverter power harmonic, and iron loss calculation flow chart of high energy density permanent magnet machine for electric propulsion system is shown. The influences of different stator outer diameter and rotor inner diameter on iron loss are analyzed by using the finite element method. Through the above analysis, a 30 kW high energy density permanent magnet machine was designed. Then the noload test and iron loss separation test were carried out, verifying that the machine has very low core loss.

A Novel Method for Establishing an Efficiency Map of IPMSMs for EV Propulsion Based on the Finite-Element Method and a Neural Network

In this paper, we introduce a novel method for establishing an efficiency map of interior permanent-magnet synchronous motors that are used for electric vehicle propulsion, by employing the finite-element method (FEM) and a neural network (NN) to reduce the analysis time. The electro-magnetic analysis of motors using the FEM, particularly iron loss analysis, is significantly time-consuming owing to the nonlinearity and the post-processing. Moreover, to obtain an efficiency map, a data map of the d-q flux linkages based on the d-q currents should be established. At this stage, we compute the flux densities in all the elements, and they are learned by the NN to obtain a function of the d-q currents. Subsequently, the iron losses at all operating points are calculated using the learned data via the harmonic loss method. The results of the proposed method indicate that the time required to obtain the efficiency map is reduced; furthermore, the results are validated via a comparison with the FEM results.

Investigation and Prediction of High-Frequency Iron Loss in Lamination Steels Driven by Voltage-Source Inverters Using Wide-Bandgap Switches

The availability of wide-bandgap (WBG) power switches makes it possible to excite electric machines with much higher pulsewidth modulation (PWM) switching frequencies. This article experimentally characterizes the magnetic and iron loss properties of lamination steels over a wide range of PWM frequencies and magnetization states excited by a voltage-source inverter using GaN-based WBG switches. With the collected hysteresis loop and iron loss data, a new frequency-interconnected dynamic Jiles-Atherton (J-A) model has been developed explicitly for PWM-induced iron loss analysis. Experiments have been conducted to verify the model prediction accuracy over a broad range of operating conditions. The proposed model has been subsequently integrated with a dynamic hysteresis model devoted to fundamental field iron loss estimation, providing an accurate and efficient tool for total iron loss estimation during PWM voltage excitation using high-frequency WBG devices. This article includes an investigation of the impact of elevated fundamental frequencies and field amplitudes on the total iron loss including comparisons between analytical predictions and experimental test results.

Iron Loss Analysis of a Concentrated Winding Type Interior Permanent Magnet Synchronous Motor with Single and Dual Layer Magnet Shape

In this study, the iron losses of high flux density concentrated winding-type interior permanent magnet synchronous motors for three different magnet shapes (single-V, single-flat, and dual-delta) and rotor structures are analyzed and compared. Iron loss is analyzed using the classical Steinmetz equation (CSE) based on the frequency separation approach using the iron loss material table, and each rotor type is compared. In addition, to validate the hysteresis loss for each rotor type, two additional analyses are performed. In the methods considered, the number of minor loops is counted, and the area is calculated based on DC bias. The eddy current loss is compared using two approaches: CSE base frequency separation and the homogenization method considering the skin effect. This study primarily focuses on the comparison of relative iron losses based on different rotor topologies instead of absolute comparisons.

Iron loss and temperature analysis of switched reluctance motor for electric vehicles

Based on a four-phase 8/6 structure switched reluctance machine for electric vehicles, the influence of different magnetic pole distributions on iron loss and temperature field is studied here. Firstly, by fitting the core silicon sheet iron loss data of the prototype, a mathematical calculation model of switched reluctance iron loss is constructed. Then, in order to analyse the flux density waveform of the iron core, a 2D finite element model is proposed. Under different magnetic pole distributions, the magnetic flux densities of the iron core are compared and the iron loss is calculated as well. Finally, the simulation results are obtained by establishing the 2D finite element thermal model of the prototype and analysed. Then, the experimental test platform is built and experimental data are recorded and analysed. By comparing the experimental results, it is found that the temperature rise is well consistent with the temperature rise of the 2D finite element thermal model.

Dynamic Hysteresis Modeling for Magnetic Circuit Analysis by Incorporating Play Model and Cauer’s Equivalent Circuit Theory

Quantitative analysis of iron loss taking magnetic hysteresis behavior into account is essential to development of high-efficiency electric machines. In a previous article, a novel magnetic circuit model incorporating a play model was proposed. It was clear that the proposed model can calculate the hysteresis loop of the magnetic reactor with high accuracy and high speed. However, there is a possibility for further improvement in the calculation accuracy of the minor loop generated from carrier harmonics under PWM excitation because the influence of the skin effect cannot be considered. Therefore, this article describes that the Cauer's equivalent circuit theory, which can represent dynamic hysteresis characteristics considering the influence of the skin effect, is applied to the magnetic circuit model, and indicates the validity of the proposed method experimentally.

Iron Loss Analysis of Permanent-Magnet Machines by Considering Hysteresis Loops Affected by Multi-Axial Stress

This article describes a method to calculate iron loss of permanent-magnet machines by considering the hysteresis loops affected by multi-axial stress. A simple hysteresis model is introduced and modified by reluctivity and hysteresis loss increase ratios, which can be determined by core material experiments under uniaxial stress. This model is coupled with time-stepping finite-element analysis. The validity of the proposed method is confirmed by the core material experiments under multi-axial stress and measured characteristics of permanent-magnet machines. It is clarified that the accuracy of the proposed method is acceptable.