Loss Separation Method Research Articles

Magnetic and dielectric properties of low‐loss MnZn ferrites with wide temperature stability

AbstractTo meet the needs for higher energy efficiency and a wide operating temperature range of electric vehicles, the low‐loss MnZn ferrites in a wide temperature range have been developed by optimizing the Fe content and the oxygen partial pressure (PO2) during the sintering process in this work. For the optimal sample, power loss at 300 kHz/100mT is 204 kW/m3 at 25°C and remains below 290 kW/m3 in the wide temperature range from ‐10 to 120°C. The loss separation method was employed to clarify the effects of the Fe content and PO2 on power loss. The equivalent circuit model has been employed to fit the complex impedance and it is found that the increase of PO2 enhances both the grain resistance Rg and the grain boundary resistance Rgb. The enhancement of Rgb is mainly responsible for the reduction of eddy current loss and consequently power loss. Dielectric permittivity is as large as about 15000 in this series of samples due to the electric polarization at the rich grain boundaries. Dielectric loss is very low between ‐50 and 150°C and has little contribution to the energy loss.

Microstructure and properties of FeSiCr/Al2O3/epoxy resin soft magnetic composites with high flowability by dry milling and coupling modification

FeSiCr/Al2O3 modified powders were prepared by dry milling and coupling for different durations, and FeSiCr/Al2O3 epoxy resin composites were prepared by banburying and low-pressure molding. The melt index, bending strength, magnetic permeability, and magnetic loss of the FeSiCr/Al2O3 epoxy resin composites were measured. The microstructures of the different FeSiCr/Al2O3 modified powders and FeSiCr/Al2O3 epoxy resin composites were observed using scanning electron microscopy (SEM), and their effects on the flowability, magnetic, and mechanical properties of the composites are discussed. The results showed that dry milling and coupling modification greatly improved the flowability of the FeSiCr/Al2O3/epoxy resin composites. Moreover, the bending strength and effective magnetic permeability increased, and the core loss decreased. Based on the loss data, a new loss separation method that is different from the conventional low-frequency method is proposed. Residual, hysteresis, and eddy current loss were in descending order in the frequency range of 100–2000 kHz.

A Line Loss Separation Method Based on Topology-aware Correlations and Nonlinear Impedance

Due to the varying order and hierarchical relationship of different meters on the same line, the variation pattern of line loss and electricity consumption is not obvious, making it difficult to separate them accurately. To address this issue, an innovative method for line loss separation based on topological relationship perception and nonlinear impedance is proposed. Firstly, based on the topology recognition algorithm, we identify the order of the electricity meters and the relationship between the father and child-level electricity meters. Then, using the principle of topology relationship, we accurately measure the impact of the father and child level electricity meters on the overall line loss electricity quantity. Combined with data difference and matrix difference methods, the fixed loss value is offset. On this basis, a sliding window method is used to draw the curve change of nonlinear impedance and loss of electricity quantity. By analyzing the approximate continuous relationship between electricity consumption and line loss rate through curves, the line loss electricity consumption can be effectively separated. The results indicate that the proposed method has a better performance compared to other methods.

Loss Calculation, Analysis, and Separation Method of 550 000 r/min Ultrahigh-Speed Permanent Magnet Motor

Loss characteristics and loss separation methods of ultrahigh-speed permanent magnet motors (UHSPMSM) are comprehensively studied in this article. In view of the influence of stator structure, material, winding type, control method, and fluid dynamics, the ac copper loss equivalent calculation model, fluid dynamic model, and finite element simulation model are established, respectively, to calculate and analyze the loss of each part of UHSPMSM. Moreover, a set of loss separation methods in dynamic is designed, which can separate stator core loss, dc copper loss, eddy copper loss, rotor eddy current loss, and mechanical friction loss of UHSPMSM one by one under the condition of considering the high-frequency electromagnetic field and fluid dynamic. A 550 000 r/min prototype and back-to-back loss separation setup is built to complete the experiment. Finally, loss distribution of the motor is obtained, which provides a certain reference for the loss research of an ultrahigh speed motor.

Copper loss analysis and loss separation method in a dynamic process of ultra‐high speed motor with slotless stator

AbstractDifferent from the copper loss of general permanent magnet (PM) motors, the copper loss of ultra‐high‐speed permanent magnet motors (UHSPMSM) includes DC losses and eddy current losses, which lead to difficulty in analysis. In consideration of the influence of speed, wire diameter and current harmonic loss, DC copper loss and eddy current copper loss are calculated and analysed, respectively, so as to find the main excitation source of copper loss of UHSPMSM. Then, in order to calculate the Litz wire loss in a slotless stator, a Litz wire loss equivalent model is established, which can be used to accurately and quickly calculate the DC loss and eddy current loss of Litz wire independently. Finally, a copper loss separation method is designed to test copper loss of 550,000 rpm UHSPMSM considering the influence of the rotor PM flux at ultra‐high speed. The theoretical analysis and experimental results verify each other. In the end, the experimental results verify the effectiveness of theoretical analysis.

Experimental study on the influence of high frequency PWM harmonics on the losses of induction motor

For the purpose of studying the influence of high frequency PWM harmonics on the losses of induction motor, this paper first introduces the latest international standard IEC/TS 60034-2-3 for the separation of the losses and the measurement of the efficiency of induction motor under PWM power supply. Then, considering that the skin effect of windings in induction motors under the condition of PWM power supply more apparent, this paper uses the stator AC resistance to replace the stator DC resistance in the IEC/TS 60034-2-3 standard to obtain more accurate separation results. On this basis, an improved method of loss separation for converter-fed induction motor is proposed by using the accurate time-step finite element method to calculate the rotor copper loss under no-load condition which cannot be considered in IEC/TS 60034-2-3 standard. Finally, this method is used to measure and separate the losses of a 5.5 kW converter-fed motor under different operating conditions. The results show that the loss of induction motor which is driven by PWM converter is obviously greater than that of sinusoidal drive, especially under light load or no load condition. The whole no-load losses of the motor driven by PWM converter increases by more than 20.0% compared with that of the sinusoidal driving condition.

Improvement on Loss Separation Method for Core Loss Calculation Under High-Frequency Sinusoidal and Nonsinusoidal Excitation

The original loss separation formula introduced by Bertotti has long been utilized mainly for low-frequency sinusoidal applications. In this article, the traditional method is improved to fit into the core loss calculation under higher frequency sinusoidal and nonsinusoidal excitations, verified by the measured data of nanocrystalline material that is often used in medium-frequency transformers (MFTs). For high-frequency sinusoidal waveform, it is proposed that the exponent of the excess loss needs to be reidentified, and it is necessary to consider the skin effect for hysteresis and eddy current loss calculation under broader frequency scope. When the core is supplied with nonsinusoidal excitation (square and rectangular waveform), a new empirical method is derived based on the concept of effective frequency and the loss separation results, with which the estimation accuracy is greatly guaranteed compared to empirical methods originated from the Steinmetz equation such as improved generalized Steinmetz equation (iGSE). Due to clear separation of loss components, the new method has the potential to precisely predict losses for higher frequency applications.

삼상유도전동기 효율의 측정불확도 평가방법 연구

In this paper, we propose a method of calculating the measurement uncertainty for the result calculated through the loss separation method, which is one of the efficiency measurement methods of three-phase induction motors. The proposed algorithm calculates the uncertainty for the factors that affect the calculation of each input quantity and then proceeds according to the procedure in Table 2 using a mathematical model. To prove the validity, the efficiency of a 2.2kW three-phase induction motor was measured. The true value of efficiency considering the proposed measurement uncertainties was estimated to be in the range of 88.17 to 88.55%. By the way, considering the tolerance range (1-η)×(-15)% for the reference value 89.5% for measuring the efficiency of the three-phase induction motor, the allowable efficiency reference value is 87.93%. Therefore the estimated efficiency true value should be judged to satisfy the minimum consumption efficiency.

Rotor Investigation of High-Speed Permanent Magnet Motor with Roundness Error and CFD-Thermal Distribution Analysis

The rotor overtemperature caused by losses is one of the important issues for the high-speed electrical machine. This paper focuses on the rotor loss analysis and CFD-thermal coupling evaluation for 105 kW, 36,000 r/min HSPMSM. Three types of sleeve materials as carbon-fiber, Titanium alloy, and stainless steel are introduced in this paper, researching the effects of sleeve conductivity, thickness and rotational speed on rotor eddy current loss, balancing rotor mechanical strength. The sleeve made of titanium alloy material with a thickness of 3.5 mm is chosen to effectively suppress the rotor eddy current loss in high-speed motors in the paper. The air friction loss becomes significant based on the PM motor at high rotational speed. The roundness error of the rotor sleeve has the important impact on the air friction loss of the rotor and the rotor temperature of the motor, which leads to the over temperature of the rotor. Therefore, based on the CFD fluid model, the influence of roundness error, cooling parameters, rotational speed and temperature boundary on the air friction loss is studied in detail, and the expression is summarized to provide reference for estimating the air friction loss. According to the rotor structure in this paper, the optimal cooling air inlet velocity is 10 m/s. Finally, the loss separation method is used to obtain the air friction loss measurement results. The accuracy of the finite element calculation results of air friction loss is verified through the experimental data. The temperature rise of the HSPMSM was also measured with 5.5% error. In this paper, the conclusion and analysis method could provide some reference for the research of the rotor structure and the improvement of the efficiency of HSPMMs.

Equivalent magnetic circuit method of estimating iron losses in induction motor spindles

The iron losses in the motor of motorized spindles have a significant effect on their heat generation, thermal deformation, and machining accuracy. The equivalent magnetic circuit (EMC) method for estimating iron losses in the spindle motor is proposed, where the magnetic flux density distribution of any cross section inside the spindle motor is assumed as a uniform one. A mechanical loss separation method of no load running combined with a sudden loss of power supply is also proposed. The EMC method is verified by prototype experiment and a different analysis method comparison. The EMC does not need to solve complex electromagnetic fields, and to do 2D or 3D eddy current analysis and the corresponding post-processing. There is only need to perform a simple magnetic circuit calculation. Therefore, it can realize a fast analysis and prediction. The proposed mechanical loss separation method requires only one prototype during a whole testing process. There is no need for any other same prototype and a coupling device. It is simpler, and can eliminate the braking torque and electromagnetic losses of the spindle motor.

A novel laser scribing method combined with the thermal stress cleaving for the crystalline silicon solar cell separation in mass production

Nowadays as the wafer sizes of the crystalline silicon solar cells get larger and larger, separating the cells becomes an essential step. However, in mass production, there is still lack of a low scribing loss and broad compatible cell separation method. In this work, a systematic investigation was conducted on the crystalline silicon solar cell separation processes, including the laser scribing and the cleaving process. Firstly, by combining a 1/4 beam splitter with the laser head, we developed a new laser scribing process, which can achieve a smaller groove width-to-depth ratio (24%) with narrower heat affected area (total width of 30 μm) compared to traditional laser optical systems. Then, we explored the minimum required scribing depths for separating four typical crystalline silicon cells by applying the thermal stress cleaving process. The Czochralski-grown substrates need only point scribing at the beginning and the end of the separating path, but if there is a metal electrode in the separation path, the scribing depth has to be about 20% of the cell thickness. At last, we analyzed the electrical and mechanical strength losses caused by different separation processes. The 20% scribing depth may cause about 30%rel mechanical strength loss. It is proved that combining this new scribing method with the thermal stress cleaving is an economical separation solution with less laser scribing loss and better compatibility for different cells. Our results would shed some light on future separating and module design efforts of solar cells.

Experimental Determination of Equivalent Iron Loss Resistance for Prediction of Iron Losses in a Switched Reluctance Machine

Switched reluctance machine (SRM) has progressed as a suitable contender in the family of electrical machines for its high starting torque and better performance in different operating conditions. The need for accurate modeling of this machine is, therefore, dependent on the accurate determination of losses of which iron loss is exigent. This article aims to determine iron loss from the equivalent circuit parameters of the machine based on the input data tables that are directly obtained from the experiments carried out on an existing four-phase, bifilar wound SRM. The procedure and necessary steps for the loss separation method are well defined and supported by the theoretical and practical results. The experimental determination of the iron losses has been compared with the predicted results under the same operating conditions.

High-Frequency Characteristic Test and Loss Calculation of TbDyFe Alloy Under Variable Temperature

The dynamic magnetic characteristic curves of TbDyFe alloy (TbxDy <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−<i>x</i></sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.9–2.0</sub> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.27 \leq x \leq 0.3$ </tex-math></inline-formula> ) under varying temperatures at different high-frequency excitation conditions were measured. The results show that when the excitation amplitude and frequency keep constants, the dynamic hysteresis loop, the permeability, and the magnetic energy loss all vary with the increase in temperature (from 10 °C to 80 °C). Their trends of temperature dependence are analyzed in detail. Based on the Bertotti loss separation method and experimental data, a magnetic energy loss calculation model for TbDyFe alloy under variable temperature conditions is proposed. The model considers the influence of high-frequency hysteresis characteristics and skin effect. It introduces temperature-related terms to modify the loss coefficients. The calculation results are compared with the experimental ones at different temperatures. It shows that this calculation method can accurately calculate the magnetic energy losses under variable temperature at higher frequencies (1–20 kHz). This research can provide an experimental and theoretical support for high-frequency engineering application of magnetostrictive materials.

Parameter Modeling Analysis of a Cylindrical Ferrite Magnetic Shield to Reduce Magnetic Noise

Magnetic field shields are important for electronic equipment, ultrahigh-sensitivity sensors, and electrical instruments. For ultrahigh-sensitivity atomic sensors, in particular, ferrite shields with low intrinsic magnetic noise are widely used. In this article, the calculation methods of longitudinal and transverse magnetic noise, which are calculated by loss, are analyzed. The experimental results confirm the feasibility of the model. Using the loss separation method, it is proved that the loss of ferrite magnetic shielding is mainly hysteresis loss, which is below 100 Hz. To effectively reduce the magnetic noise, we analyze the effect of structure parameters on the longitudinal and transverse magnetic noise, and the optimized parameters are obtained. The results show that the longitudinal magnetic noise decreases with the increasing aspect ratio and stabilize eventually. When the aspect ratio exceeds 1, the transverse magnetic noise remains practically unchanged. When the external diameter is fixed, by optimizing the thickness of the magnetic shield, the optimal solution for the longitudinal and transverse magnetic noise is obtained.

Comprehensive Investigation of Loss Calculation and Sequential Iterative Fluid-Solid Coupling Schemes for High-Speed Switched Reluctance Motors

This article proposes a comprehensive investigation method for loss calculation and temperature rise prediction in high-speed and high-power switched reluctance machines (SRMs). The losses are analyzed in details and the sequential iterative fluid-solid coupling (SIFSC) scheme is proposed for thermal analysis. In the iterative design stage of the SRM, it is important and urgent to figure out the power losses and temperature distribution in the motor, which affects the endurance of the motor operation, such as the maximum speed and highest operating temperature. A simplified finite element (FE) model of a turn and a proximity loss separation method are developed for the skin and proximity (SP) loss reduction. Then, an additional eddy current loss calculation method is developed with a simplified FE model of the winding. Additionally, the SIFSC scheme is further proposed and implemented by sequentially calculating the fluid and solid fields for airflow velocity and temperature distribution. Compared to conventional thermal calculation schemes, the proposed SIFSC scheme is faster than direct coupling methods and more accurate than thermal network methods. The accuracy and effectiveness of this scheme is verified by the simulation and experimental test for a 160 kW and 18000 r/min 6/2 SRM prototype.

Comment on “Novel Fe-based nanocrystalline powder cores with excellent magnetic properties produced using gas-atomized powder” [J. Magn. Magn. Mater. 452 (2018) 442–446

It is pointed out that some mistakes in research article (Chang, Liang, et al., 2018). There were existing mistakes in the conception, theoretical analysis method and conclusion of loss separation. I have shown that authors to obtained conflict between the experimental data and theoretical analysis conclusion. There were existing serious mistakes in the experimental data measurement in the article. Loss per cycle versus frequency curves for effective permeability μe = 60 of Fe-Si powder core are plotted as a correction. The rate of hysteresis loss power in power loss (Ph/Pt) at different magnetic flux densities and frequencies for effective permeability μe = 60 of Fe-Si powder core is demonstrated.

Calculation of core loss under distorted flux density with minor hysteresis loops for laminated steel structure

Accurate prediction of core losses has been a crucial aspect in the field of electromagnetics for several decades. Extensive experimental results have shown that the core loss under harmonic excitation is more complicated than that under sinusoidal excitations, which means that the traditional core loss calculation methods are no longer applicable under distorted flux. In order to determine an efficient numerical approach when minor hysteresis loops occur, a harmonic magnetic test platform is used to study the effect of the variation of B–H properties on the iron loss and magnetic flux density of grain oriented silicon steel lamination under different supply voltages. A simple method, which could be used to predict the iron losses in thin laminations due to a number of non-sinusoidal waveforms with or without minor loops, for estimating the iron loss based on the loss separation method is proposed. The errors are substantially lower than those of conventional models while saving time.

FeSiCr@NiZn SMCs with ultra-low core losses, high resistivity for high frequency applications

Soft magnetic composites (SMCs) are widely applied in electronic devices and components, such as inductors, as they possess the highly-saturated magnetization M s of metallic materials and the highly-insulating characteristics of non-metals. However, with the development of electronic systems that require high-frequency operation, high-energy-transfer efficiency, and miniaturization, the suppression of core losses P cv in their SMCs remains a considerable challenge. Herein, we explore ways to improve the frequency dependence of core losses by using various concentrations of NiZn ferrite (0.0–5.0 wt%) to coat FeSiCr magnetic powders. The microstructural, magnetic, dielectric, and core loss performances of FeSiCr@NiZn SMCs are investigated in detail. Energy dispersive X-Ray spectroscopy (EDS) mapping confirmed that the FeSiCr magnetic powders were able to be well coated with NiZn ferrite. Core loss separation method was utilized to calculate hysteresis losses P h and eddy current losses P e from 25 to 800 kHz at 10 mT and 25 °C. With increasing NiZn ferrite concentration, both P cv and P h initially decreased and subsequently increased, while P e decreased monotonically. The sample with 3.0 wt% NiZn ferrite had the best overall performance: saturation magnetization M s = 157 emu/g, coercive force H c = 4.6 Oe, effective permeability μ e = 60, resistivity ρ = 1.25 × 10 4 Ω∙m, and core losses P cv = 38 mW/cm 3 (at 800 kHz, 10 mT, and 25 °C). The excellent electromagnetic properties of these novel FeSiCr@NiZn SMCs give them enormous application potential in the fields of power transmission and conversion. • EDS mapping confirmed that the FeSiCr powders were well coated with NiZn ferrite. • The high-resistance layer of NiZn ferrite are beneficial for the reduction of P cv . • FSC0NZ possessed optimum P cv = 38 mW/cm 3 (at 800 kHz, 10 mT, and 25 °C).

Improved gyrator–capacitor model considering eddy current and excess losses based on loss separation method

The traditional equivalent circuit model based on the reluctance–resistance analogy method is used to model electromagnetic equipment in power systems. However, this model has unreasonable analogy, incomplete magnetic circuit information, and is difficulty to expand. This study proposes an improved gyrator–capacitor (G–C) model and its parameter extraction method for the modeling of electromagnetic devices in power systems. An improved G–C model considering eddy current and excess losses is proposed on the basis of the loss separation method and by utilizing the physical concept of resistance. On the basis of the proposed model, simple calculation methods of the instantaneous loss power and density of the core are presented. A parameter extraction method considering the fitting effect of the entire hysteresis loop and special points is proposed in accordance with the idea of curve fitting. The proposed model and its parameter extraction method are verified by comparing the calculated results with the measured results.

An Improved Loss-Separation Method for Transformer Core Loss Calculation and Its Experimental Verification

The separation of core loss plays an important role in the transformer loss calculation. To obtain more accurate core loss, based on the comparison and analysis on two traditional loss separation methods, an improved loss separation method was proposed for the core loss calculation of the transformer in a wide magnetic flux density range. Firstly, through analysis the eddy current loss was obtained by direct calculation, while the hysteresis loss was obtained by performing the quasi-static magnetization process. And the coefficient corrections for the hysteresis loss and eddy current loss calculation were conducted by using the experimental data. The result comparison between the proposed method and traditional ones were made. Secondly, by setting up the Epstein frame platform, the total loss and static hysteresis loss of 14 types of industrial silicon steel were measured. In addition, the suggestive values and the corresponding value range of the loss coefficients of 14 kinds of industrial silicon steel were given. The results obtained by the proposed method were in good agreement with the measured data in the wide magnetic flux density range, while the suggestive values and the corresponding value range of 14 kinds of industrial silicon steel can provides an effective data support for the accurate core loss calculation.