Based on the force-heat equivalence energy density principle,a theoretical model for magnetic metallic materials is developed,which characterizes the temperature-dependent magnetic anisotropy energy by considering the...Based on the force-heat equivalence energy density principle,a theoretical model for magnetic metallic materials is developed,which characterizes the temperature-dependent magnetic anisotropy energy by considering the equivalent relationship between magnetic anisotropy energy and heat energy;then the relationship between the magnetic anisotropy constant and saturation magnetization is considered.Finally,we formulate a temperature-dependent model for saturation magnetization,revealing the inherent relationship between temperature and saturation magnetization.Our model predicts the saturation magnetization for nine different magnetic metallic materials at different temperatures,exhibiting satisfactory agreement with experimental data.Additionally,the experimental data used as reference points are at or near room temperature.Compared to other phenomenological theoretical models,this model is considerably more accessible than the data required at 0 K.The index included in our model is set to a constant value,which is equal to 10/3 for materials other than Fe,Co,and Ni.For transition metals(Fe,Co,and Ni in this paper),the index is 6 in the range of 0 K to 0.65T_(cr)(T_(cr) is the critical temperature),and 3 in the range of 0.65T_(cr) to T_(cr),unlike other models where the adjustable parameters vary according to each material.In addition,our model provides a new way to design and evaluate magnetic metallic materials with superior magnetic properties over a wide range of temperatures.展开更多
Soft magnetic material with high saturation magnetization(Ms)and high resistance(ρ)is vital to improve the power density and conversion efficient of modern electrical magnetic equipment.Yet,increasing Ms is always at...Soft magnetic material with high saturation magnetization(Ms)and high resistance(ρ)is vital to improve the power density and conversion efficient of modern electrical magnetic equipment.Yet,increasing Ms is always at the expense of high resistivity,such as soft magnetic alloys substitute for the ferrite.In this work,the superior comprehensive electromagnetic properties,namely the close association of high saturation magnetization and high resistivity,are combined in a new way in a newly Fe-N based magnetic materials.A high resistance oxide interface engineering was constructed between the conducting ferromagnetic phases in the process of spark plasma sintering(SPS)to achieve superior electromagnetic properties.The ZnO compositeγ’-Fe_(4) N bulk has a maximum resistivity of 220μΩ cm and a Ms of up to 156.02 emu/g,while the TiO_(2)compositeγ’-Fe_(4) N bulk has a maximum resistivity of 379μcm and a Ms of 149.7 emu/g.The research findings offer valuable insights for the advancement of the next generation of soft magnetic materials,which hold significant potential for use in high-frequency,high-efficiency,and energy-saving power equipment applications.展开更多
The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasma owing to its compact, relatively low-cost and easy-to-handle characteris...The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasma owing to its compact, relatively low-cost and easy-to-handle characteristics. The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design, because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation. This work proposes analytical formulas of the criterion of magnetic saturation for the cores when the transformer drives practical loads. Furthermore, an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores. The numerical simulation with the model is used to evaluate the validity of the criterion. Both the criterion and the model are found to be in agreement with the experimental data.展开更多
Fe-based metallic glasses have garnered significant attention due to their low coercivity force and core loss.Enhancing the saturation magnetic flux density(Bs)of Fe-based metallic glasses is crucial for their industr...Fe-based metallic glasses have garnered significant attention due to their low coercivity force and core loss.Enhancing the saturation magnetic flux density(Bs)of Fe-based metallic glasses is crucial for their industry applications.This work constructed a dataset comprising330 training data and 157 test data.The support vector regression model surpassed the tree-based ensemble models in the test set and demonstrated comparable accuracy to the tree-based ensemble models in the training set.Additionally,we proposed an indicator for Bsbased on symbolic regression.This newly proposed indicator exhibits a Pearson correlation coefficient exceeding 0.92 with Bs.The present work provides a simple and accurate formula for predicting the Bsof Fe-based amorphous alloys,demonstrating the effectiveness of machine learning approaches in discovering novel soft magnetic materials.展开更多
Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror method...Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror methods,which are time-consuming and inefficient.Herein,we present an interpretable machine learning(ML)algorithm for the effective design of advanced FNAs with improved B_(s)and low H_(c).Firstly,the FNAs datasets were established,consisting of 20 features including chemical composition,process parameters,and theoretically calculated parameters.Subsequently,a three-step feature selection was used to screen the key features that affect the B_(s)and H_(c)of FNAs.Among six different ML algorithms,extreme gradient boosting(XGBoost)performed the best in predicting B_(s)and H_(c).We further revealed the association of key features with B_(s)and H_(c)through linear regression and SHAP analysis.The valence electron concentration without Fe,Ni,and Co elements(VEC1)and valence electron concentration(VEC)ranked as the most important features for predicting B_(s)and H_(c),respectively.VEC1 had a positive impact on B_(s)when VEC1<0.78,while VEC had a negative effect on H_(c)when VEC<7.12.Optimized designed FNAs were successfully prepared,and the prediction errors for B_(s)and H_(c)are lower than 2.3%and 18%,respectively,when comparing the predicted and experimental results.These results demonstrate that this ML approach is interpretable and feasible for the design of advanced FNAs with high B_(s)and low H_(c).展开更多
The traditional high-temperature annealing process is difficult to control the morphology and size of the crystallization phases in amorphous alloy systems with high ferromagnetic element content,lead-ing to mechanica...The traditional high-temperature annealing process is difficult to control the morphology and size of the crystallization phases in amorphous alloy systems with high ferromagnetic element content,lead-ing to mechanical brittleness and soft magnetic properties deterioration.Here,we developed a flexible-annealing technique and successfully achieved a fine nanocrystalline structure in a high-ferromagnetic-content system of(Fe_(0.8)Co_(0.2))_(85)Si_(2)B_(12)Cu_(0.8)Mo_(0.2).It is exciting that the(Fe_(0.8)Co_(0.2))_(85)Si_(2)B_(12)Cu_(0.8)Mo_(0.2) nanocrystalline alloy exhibits high Bs up to 1.88 T,low coercivity of 6.3 A m-1,as well as good plas-ticity.The excellent comprehensive properties are attributed to the controllable construction of di-luted amorphous-nanocrystalline structure,the rapid release of internal stress,and the suppression of relaxation-induced uniformity achieved by the flexible annealing process.The results provide a fast and new paradigm for the development of next-generation high-Bs soft magnetic materials.展开更多
The rapid-cycling synchrotron(RCS)is a crucial device for proton beam acceleration at the China Spallation Neutron Source,operating at a repetition frequency of 25 Hz.The beam power was increased from 100 kW to 140 kW...The rapid-cycling synchrotron(RCS)is a crucial device for proton beam acceleration at the China Spallation Neutron Source,operating at a repetition frequency of 25 Hz.The beam power was increased from 100 kW to 140 kW.This increase makes the on-orbit beam more sensitive to disturbances in various parts of the accelerator,including the RCS magnet power supply system.This paper presents a method for reducing the high-order harmonic current error in resonant power supplies for dipole magnets and examines its impact on the horizontal orbit offset of the beam.It adopts a control scheme that combines high-order harmonic current compensation with PI double-loop control of the resonant power supply.By utilizing the existing digital controller hardware in the RCS power supply system,this study demonstrates how to achieve precise control of the 50 Hz harmonic current output in a cost-effective manner.Ultimately,it enhances performance by reducing the current error by up to 50%and provides methodological support for future upgrades to the power supply system.Such improvements enhance the stability of the RCS,reducing the beam horizontal orbit deviation by at least 19.8%.展开更多
Monodispersed Fe nanospindles and nanoparticles were successfully synthesized through environmentfriendly reductive annealing ？-Fe OOH nanorods. Effects of annealing temperature and reaction atmosphere on microstruct...Monodispersed Fe nanospindles and nanoparticles were successfully synthesized through environmentfriendly reductive annealing ？-Fe OOH nanorods. Effects of annealing temperature and reaction atmosphere on microstructure, phase, and magnetic property of Fe nanostructures were investigated.The as-obtained pure Fe nanoparticles with mean size of 45 nm had a high saturation magnetization up to 207 emu/g, close to that of bulk material（218 emu/g）, which exhibited high air stability. After exposing in air for 2 and 7 days, the as synthesized Fe nanoparticles still showed high magnetization of 182 and141 emu/g, respectively.展开更多
This paper deals with an analytical method to effectively calculate the inductance of an exterior-rotor switched reluctance motor(SRM),which evaluates the winding inductance of both the active section and the end sect...This paper deals with an analytical method to effectively calculate the inductance of an exterior-rotor switched reluctance motor(SRM),which evaluates the winding inductance of both the active section and the end section,accounting for the influence of core saturation.According to the inductance calculated by the analytical model,the flux linkage table and torque table can be established,and the steady state performance such as phase current,flux linkage,copper loss and core loss can be predicted.Effectiveness of this method is verified by the finite element method as well as by experimental results of a 12/8 SRM prototype.展开更多
This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is bas...This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is based on the derivation that the peak acceleration is dependent on the product of phase current and current gradient idi/dt.However,the derivation may cause errors due to saturation effect.Thus in this paper,the discrete sample data are firstly acquired based on DC pulse measurement method,by which electromagnetic,torque and peak acceleration characteristics can all be acquired.Then the entire peak acceleration characteristics are obtained by improved Least Square Support Vector Machine(LSSVM).Based on the obtained static peak acceleration characteristics,the time-varied radial vibration model is established based on superposition of natural oscillations of dominant vibration modes.Finally,a simulation model is built up using MATLAB/Simulink.The good agreement between simulation and experiment shows that the proposed method for modeling is feasible and accurate,even under saturation.In addition,since LSSVM does not need any prior knowledge,it is much easier for modeling compared with other existing literatures.展开更多
Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was o...Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was observed in micro-gravity(μG) condition produced by a compact drop-shaft installed in a ordinary laboratory room.Magnetization Ms per unit mass of the grain is obtained by analyzing the above-mentioned translations in terms of a energy conservation rule;here conservation of the sum of field-induced potential mMsH and kinetic energy 1/2/mv^2 is considered for a particle with mass m.The present method of obtaining Ms is free of measuring the mass of sample;this is because the field-gradient force is a volume force that is proportional to m.The method is also free of an interfering signal emitted from the sample holder.Accordingly,Ms is detectable irrespective of sample size,provided that the field-induced translation is observable.The above-mentioned procedure to estimate Ms from filed-induced translation is a step to obtain a reliable magnetic data from a single nano-sized grain.The efficiency of material identification was recently confirmed on various solid grains,which was based on diamagnetic magnetization data obtained from its translations caused by field-gradient repulsive force.A diamagnetic material generally possesses an intrinsic value of magnetic susceptibility and its anisotropy.The present results on nickel grains indicate that the principle of material identification based on its magnetization data is applicable for the three major category of magnetic materials,namely ferro-(or ferri-) magnetic, paramagnetic and diamagnetic material.展开更多
Lagrange-Maxwell＇s equation is extended firstly. With the theory of electromechanical analytical dynamics, the magnetic complement energy in air gap of generator is acquired. The torsional vibration differential equa...Lagrange-Maxwell＇s equation is extended firstly. With the theory of electromechanical analytical dynamics, the magnetic complement energy in air gap of generator is acquired. The torsional vibration differential equations with periodic coefficients of rotor shafting of generator which is in the state of.magnetic saturation are established. It is shown that the magnetic saturation may cause double frequency electromagnetic moment. By means of the averaging method, the first approximate solution and corresponding solution of the primary parametric resonance is obtained. The characteristics and laws of the primary parametric resonance excited by the electromagnetism are analyzed and some of new phenomena are revealed.展开更多
The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) ...The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=0.05.The hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared spectroscopy.The creation of the M-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray diffractograms.The occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> 0.The refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter ratio.The crystal structure plotted from the refined XRD data reveals the occupancy of the ions at different lattice sites.The XPS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent elements.The nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's formula.The analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) phase.The morphology of the hexaferrites was analyzed from the FESEM profiles of the ferrite samples.The magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.M,and Mossbauer spectroscopy,respectively.The hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the study.The substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.展开更多
Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For th...Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For the sample with active Cu as the top electrode,the formation and rupture of metallic Cu conductive filaments can explain the resistive switching behavior;for the other samples,the generation and annihilation of nitrogen vacancies under the electric stimuli may contribute to the occurrence of resistive switching.Taking advantage of the formed and broken Co-N bonds during resistive switching,the saturation magnetization of the BN-Co films can be modulated.Thus,it investigated the resistive switching behavior of BN and BN-Co materials in this work.Similar to that of oxide materials,the resistive switching behaviors of the nitrides may be attributed to the movement of cations or anions within the dielectric or electrodes during the application of voltage.Additionally,ion migration may lead to the formation or breaking of Co-N bonds,which can effectively regulate the magnetism of BN-Co materials.This study extends resistive switching materials to nitrides,enabling the regulation of magnetism along with resistance changes,thus providing insights for the design of novel voltage-controlled magnetic devices and achieving multi-functionality.展开更多
Nowadays,there is considerable research interest in proposing modern permanent magnet(PM)electric machine structures for applications such as electric vehicles.Several radial and axial topologies with different arrang...Nowadays,there is considerable research interest in proposing modern permanent magnet(PM)electric machine structures for applications such as electric vehicles.Several radial and axial topologies with different arrangements of PM in the stator and rotor have been introduced for PM Vernier motors(PMVM)with the aim of increasing the performance characteristics such as power factor,efficiency,rotational torque torque density and wider constant torque-speed region.Meanwhile,the spoke PM arrangement has provided higher torque density than the surface and V-shaped arrangement.But in contrast,the V-shaped arrangement has a more sinusoidal flux and less cogging torque.In this paper,a 620 W,12-slot 16-pole Vernier PM motor with a fractional slot arrangement.Consequent K-shaped pole is introduced,which has the advantages of spoke and V-shaped magnetic arrangements.After presenting and confirming the concept of the proposed structure based on functional comparison with conventional structures,an analytical modeling based on the harmonic analysis method is introduced to accurately predict the performance of the machine,and finally the proposed structure is prototyped and the experimental results are simulated and modeling are compared.展开更多
For permanent magnet synchronous machines(PMSMs),accurate machine model is critical for high performance maximum torque per ampere(MTPA)control.However,as motor speed increases,the nonlinearity such as core loss effec...For permanent magnet synchronous machines(PMSMs),accurate machine model is critical for high performance maximum torque per ampere(MTPA)control.However,as motor speed increases,the nonlinearity such as core loss effect will affect the accuracy of machine model and thus the performance of online MTPA control.This paper firstly investigates the performance of the model based MTPA control under different motor speeds through modeling,simulation and experiments,which indicates that the accuracy of MTPA control is greatly reduced especially under high-speeds due to machine nonlinearity.Hence,this paper proposes an efficient nonlinearity compensation model based on polynomial fitting to model and compensate the MTPA error as motor speed increases.Considering both core loss and magnetic saturation effects,the compensation model is a nonlinear polynomial of speed and stator current.To obtain the fitting data,a derivative modeling method is proposed to compute the actual and detected MTPA angles under different speeds,in which the derivative model of torque to current ratio is fitted and the MTPA angle is obtained by setting the derivative model to zero.The proposed compensation model is both computation effective and easy to use for MTPA control,as it computes the compensation term that can be directly combined to other model-based methods.The proposed model is evaluated with experiments and comparisons on a test motor to show the performance improvement.展开更多
Fe75Zr3Si13B9 magnetic amorphous powders were fabricated by mechanical alloying. Bulk amorphous and nanocrystalline alloys with 20 mm in diameter and 7 mm in height were fabricated by the spark plasma sintering techno...Fe75Zr3Si13B9 magnetic amorphous powders were fabricated by mechanical alloying. Bulk amorphous and nanocrystalline alloys with 20 mm in diameter and 7 mm in height were fabricated by the spark plasma sintering technology at different sintering temperatures. The phase composition, glass transition temperature （Tg）, onset crystallization temperature （Tx）, peak temperature （Tp） and super-cooled liquid region （ΔTx） of Fe75Zr3Si13B9 amorphous powders were analyzed by X-ray diffraction （XRD） and differential scanning calorimetry （DSC）. The phase transition, microstructure, mechanical properties and magnetic performance of the bulk alloys were discussed with X-ray diffractometer, scanning electron microscope （SEM）, Gleeble 3500 and vibration sample magnetometer （VSM）, respectively. It is found that with the increase in the sintering temperature at the pressure of 500 MPa, the density, compressive strength, micro-hardness and saturation magnetization of the sintering samples improved significantly, the amorphous phase began to crystallize gradually. Finally, the desirable amorphous and nanocrystalline magnetic materials at the sintering temperature of 863.15 K and the pressure of 500 MPa have a density of 6.9325 g/cm3, a compressive strength of 1140.28 MPa and a saturation magnetization of 1.28 T.展开更多
The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and s...The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.展开更多
The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and s...The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.展开更多
Bi0.85La0.15FeO3 thin film was prepared on ATO glass substrates by sol-gel technique. The effect of La doping on phase structure, film surface quality, ion valence, and ferroelectric/magnetic properties of Bio.85La0.1...Bi0.85La0.15FeO3 thin film was prepared on ATO glass substrates by sol-gel technique. The effect of La doping on phase structure, film surface quality, ion valence, and ferroelectric/magnetic properties of Bio.85La0.15FeO3 film were investigated. La doping suppressed the formation of impurity phases and the transition of Fe3＋ to Fe2＋ ions at room temperature. Compared with the un-doped BiFeO3, La-doping also increased the average grain size and the film density, which resulted in the decrease of film leakage current density. The remanent polarization and saturation magnetization were enhanced significantly by La doping. The remanent polariza- tion of Bi0.85La0.15FeO3 films gradually decreased while saturation magnetization increased with the decrease of measuring tempera- ture within a range from 50 to 300 K.展开更多
基金Project supported by the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX0391)。
文摘Based on the force-heat equivalence energy density principle,a theoretical model for magnetic metallic materials is developed,which characterizes the temperature-dependent magnetic anisotropy energy by considering the equivalent relationship between magnetic anisotropy energy and heat energy;then the relationship between the magnetic anisotropy constant and saturation magnetization is considered.Finally,we formulate a temperature-dependent model for saturation magnetization,revealing the inherent relationship between temperature and saturation magnetization.Our model predicts the saturation magnetization for nine different magnetic metallic materials at different temperatures,exhibiting satisfactory agreement with experimental data.Additionally,the experimental data used as reference points are at or near room temperature.Compared to other phenomenological theoretical models,this model is considerably more accessible than the data required at 0 K.The index included in our model is set to a constant value,which is equal to 10/3 for materials other than Fe,Co,and Ni.For transition metals(Fe,Co,and Ni in this paper),the index is 6 in the range of 0 K to 0.65T_(cr)(T_(cr) is the critical temperature),and 3 in the range of 0.65T_(cr) to T_(cr),unlike other models where the adjustable parameters vary according to each material.In addition,our model provides a new way to design and evaluate magnetic metallic materials with superior magnetic properties over a wide range of temperatures.
基金supported by National Natural Science Foundation of China(No.52071294),National Key Research and Development Program(No.2022YFE0109800)Natural Science Foundation of Zhejiang Province(No.LY20E020015)Key Research and Development Program of Zhejiang Province(No.2021C01172).
文摘Soft magnetic material with high saturation magnetization(Ms)and high resistance(ρ)is vital to improve the power density and conversion efficient of modern electrical magnetic equipment.Yet,increasing Ms is always at the expense of high resistivity,such as soft magnetic alloys substitute for the ferrite.In this work,the superior comprehensive electromagnetic properties,namely the close association of high saturation magnetization and high resistivity,are combined in a new way in a newly Fe-N based magnetic materials.A high resistance oxide interface engineering was constructed between the conducting ferromagnetic phases in the process of spark plasma sintering(SPS)to achieve superior electromagnetic properties.The ZnO compositeγ’-Fe_(4) N bulk has a maximum resistivity of 220μΩ cm and a Ms of up to 156.02 emu/g,while the TiO_(2)compositeγ’-Fe_(4) N bulk has a maximum resistivity of 379μcm and a Ms of 149.7 emu/g.The research findings offer valuable insights for the advancement of the next generation of soft magnetic materials,which hold significant potential for use in high-frequency,high-efficiency,and energy-saving power equipment applications.
基金This work was supported by the National Natural Science Foundation of China,No.10035020
文摘The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasma owing to its compact, relatively low-cost and easy-to-handle characteristics. The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design, because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation. This work proposes analytical formulas of the criterion of magnetic saturation for the cores when the transformer drives practical loads. Furthermore, an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores. The numerical simulation with the model is used to evaluate the validity of the criterion. Both the criterion and the model are found to be in agreement with the experimental data.
基金financially supported by Shanghai Pujiang Program(No.23PJ1403500)GuangDong Basic and Applied Basic Research Foundation(No.2023A1515110901)+2 种基金Shenzhen Pengcheng Peacock Project(No.NA11409004)the National Natural Science Foundation of China(Nos.U22B2064 and 51105102)and Shanghai Rising-Star Program Yangfan Project(No.23YF1411900)。
文摘Fe-based metallic glasses have garnered significant attention due to their low coercivity force and core loss.Enhancing the saturation magnetic flux density(Bs)of Fe-based metallic glasses is crucial for their industry applications.This work constructed a dataset comprising330 training data and 157 test data.The support vector regression model surpassed the tree-based ensemble models in the test set and demonstrated comparable accuracy to the tree-based ensemble models in the training set.Additionally,we proposed an indicator for Bsbased on symbolic regression.This newly proposed indicator exhibits a Pearson correlation coefficient exceeding 0.92 with Bs.The present work provides a simple and accurate formula for predicting the Bsof Fe-based amorphous alloys,demonstrating the effectiveness of machine learning approaches in discovering novel soft magnetic materials.
基金supported by the National Key R&D Program of China(Grant No.2022YFB2404101)the“Pioneer”R&D Programof Zhejiang Province(No.2023C01075)+1 种基金the Youth Innovation Promotion Association CAS(Grant No.2021294)the Ningbo Natural Science Foundation(No.2021J197).
文摘Overcoming the trade-offbetween saturation magnetic induction(B_(s))and coercivity(H_(c))of Fe-based nanocrystalline alloys(FNAs)remains a great challenge due to the traditional design relying on trial-anderror methods,which are time-consuming and inefficient.Herein,we present an interpretable machine learning(ML)algorithm for the effective design of advanced FNAs with improved B_(s)and low H_(c).Firstly,the FNAs datasets were established,consisting of 20 features including chemical composition,process parameters,and theoretically calculated parameters.Subsequently,a three-step feature selection was used to screen the key features that affect the B_(s)and H_(c)of FNAs.Among six different ML algorithms,extreme gradient boosting(XGBoost)performed the best in predicting B_(s)and H_(c).We further revealed the association of key features with B_(s)and H_(c)through linear regression and SHAP analysis.The valence electron concentration without Fe,Ni,and Co elements(VEC1)and valence electron concentration(VEC)ranked as the most important features for predicting B_(s)and H_(c),respectively.VEC1 had a positive impact on B_(s)when VEC1<0.78,while VEC had a negative effect on H_(c)when VEC<7.12.Optimized designed FNAs were successfully prepared,and the prediction errors for B_(s)and H_(c)are lower than 2.3%and 18%,respectively,when comparing the predicted and experimental results.These results demonstrate that this ML approach is interpretable and feasible for the design of advanced FNAs with high B_(s)and low H_(c).
基金supported by the Guangdong Major Project of Basic and Applied Basic Research,China(Grant No.2019B030302010)the Guangdong Basic and Applied Baic Research,China(Grant No.2020B1515130007)+2 种基金the Key Research and Development Plan of Dongguan,China(Grant No.20221200300062)the National Natural Science Foundation of China(Grant Nos.52192602,52071222,52101191,52171149)the National Key Research and Development Program of China(Grant No.2021YFA0716302).
文摘The traditional high-temperature annealing process is difficult to control the morphology and size of the crystallization phases in amorphous alloy systems with high ferromagnetic element content,lead-ing to mechanical brittleness and soft magnetic properties deterioration.Here,we developed a flexible-annealing technique and successfully achieved a fine nanocrystalline structure in a high-ferromagnetic-content system of(Fe_(0.8)Co_(0.2))_(85)Si_(2)B_(12)Cu_(0.8)Mo_(0.2).It is exciting that the(Fe_(0.8)Co_(0.2))_(85)Si_(2)B_(12)Cu_(0.8)Mo_(0.2) nanocrystalline alloy exhibits high Bs up to 1.88 T,low coercivity of 6.3 A m-1,as well as good plas-ticity.The excellent comprehensive properties are attributed to the controllable construction of di-luted amorphous-nanocrystalline structure,the rapid release of internal stress,and the suppression of relaxation-induced uniformity achieved by the flexible annealing process.The results provide a fast and new paradigm for the development of next-generation high-Bs soft magnetic materials.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(No.2023B1515120030).
文摘The rapid-cycling synchrotron(RCS)is a crucial device for proton beam acceleration at the China Spallation Neutron Source,operating at a repetition frequency of 25 Hz.The beam power was increased from 100 kW to 140 kW.This increase makes the on-orbit beam more sensitive to disturbances in various parts of the accelerator,including the RCS magnet power supply system.This paper presents a method for reducing the high-order harmonic current error in resonant power supplies for dipole magnets and examines its impact on the horizontal orbit offset of the beam.It adopts a control scheme that combines high-order harmonic current compensation with PI double-loop control of the resonant power supply.By utilizing the existing digital controller hardware in the RCS power supply system,this study demonstrates how to achieve precise control of the 50 Hz harmonic current output in a cost-effective manner.Ultimately,it enhances performance by reducing the current error by up to 50%and provides methodological support for future upgrades to the power supply system.Such improvements enhance the stability of the RCS,reducing the beam horizontal orbit deviation by at least 19.8%.
基金the National Basic Research Program of China, under grant No. 2014CB643702the National Natural Science Foundation of China, under grant Nos. 51422106, 51401228, 61428403+2 种基金the Ningbo City Scientific and Technological Project under grant No. 2012B81001the Scientific and Technological Project of Zhejiang Province under grant No. 2013TD08the China Postdoctoral Science Foundation under grant No. 2014M561524 for financial support
文摘Monodispersed Fe nanospindles and nanoparticles were successfully synthesized through environmentfriendly reductive annealing ？-Fe OOH nanorods. Effects of annealing temperature and reaction atmosphere on microstructure, phase, and magnetic property of Fe nanostructures were investigated.The as-obtained pure Fe nanoparticles with mean size of 45 nm had a high saturation magnetization up to 207 emu/g, close to that of bulk material（218 emu/g）, which exhibited high air stability. After exposing in air for 2 and 7 days, the as synthesized Fe nanoparticles still showed high magnetization of 182 and141 emu/g, respectively.
文摘This paper deals with an analytical method to effectively calculate the inductance of an exterior-rotor switched reluctance motor(SRM),which evaluates the winding inductance of both the active section and the end section,accounting for the influence of core saturation.According to the inductance calculated by the analytical model,the flux linkage table and torque table can be established,and the steady state performance such as phase current,flux linkage,copper loss and core loss can be predicted.Effectiveness of this method is verified by the finite element method as well as by experimental results of a 12/8 SRM prototype.
基金This work was supported by the National Natural Science Foundation of China under Grant 51277026 and 61674033Natural Science Foundation of Jiangsu Province under Grant BK20161148the Scientific Research Foundation of Graduate School of Southeast University under Grant YBJJ1822.(Corresponding author:Weifeng Sun.)。
文摘This paper proposes an improved method for the prediction of radial vibration in switched reluctance motor(SRM)considering magnetic saturation.In this paper,the basic modeling principle is briefly introduced,it is based on the derivation that the peak acceleration is dependent on the product of phase current and current gradient idi/dt.However,the derivation may cause errors due to saturation effect.Thus in this paper,the discrete sample data are firstly acquired based on DC pulse measurement method,by which electromagnetic,torque and peak acceleration characteristics can all be acquired.Then the entire peak acceleration characteristics are obtained by improved Least Square Support Vector Machine(LSSVM).Based on the obtained static peak acceleration characteristics,the time-varied radial vibration model is established based on superposition of natural oscillations of dominant vibration modes.Finally,a simulation model is built up using MATLAB/Simulink.The good agreement between simulation and experiment shows that the proposed method for modeling is feasible and accurate,even under saturation.In addition,since LSSVM does not need any prior knowledge,it is much easier for modeling compared with other existing literatures.
文摘Free translation caused by attractive field-gradient force was observed for Ni and ferrite(CuFe_2O_4) grains that were released in a diffuse area.In order to exclude the effect of terrestrial gravity,translation was observed in micro-gravity(μG) condition produced by a compact drop-shaft installed in a ordinary laboratory room.Magnetization Ms per unit mass of the grain is obtained by analyzing the above-mentioned translations in terms of a energy conservation rule;here conservation of the sum of field-induced potential mMsH and kinetic energy 1/2/mv^2 is considered for a particle with mass m.The present method of obtaining Ms is free of measuring the mass of sample;this is because the field-gradient force is a volume force that is proportional to m.The method is also free of an interfering signal emitted from the sample holder.Accordingly,Ms is detectable irrespective of sample size,provided that the field-induced translation is observable.The above-mentioned procedure to estimate Ms from filed-induced translation is a step to obtain a reliable magnetic data from a single nano-sized grain.The efficiency of material identification was recently confirmed on various solid grains,which was based on diamagnetic magnetization data obtained from its translations caused by field-gradient repulsive force.A diamagnetic material generally possesses an intrinsic value of magnetic susceptibility and its anisotropy.The present results on nickel grains indicate that the principle of material identification based on its magnetization data is applicable for the three major category of magnetic materials,namely ferro-(or ferri-) magnetic, paramagnetic and diamagnetic material.
文摘Lagrange-Maxwell＇s equation is extended firstly. With the theory of electromechanical analytical dynamics, the magnetic complement energy in air gap of generator is acquired. The torsional vibration differential equations with periodic coefficients of rotor shafting of generator which is in the state of.magnetic saturation are established. It is shown that the magnetic saturation may cause double frequency electromagnetic moment. By means of the averaging method, the first approximate solution and corresponding solution of the primary parametric resonance is obtained. The characteristics and laws of the primary parametric resonance excited by the electromagnetism are analyzed and some of new phenomena are revealed.
文摘The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=0.05.The hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared spectroscopy.The creation of the M-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray diffractograms.The occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> 0.The refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter ratio.The crystal structure plotted from the refined XRD data reveals the occupancy of the ions at different lattice sites.The XPS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent elements.The nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's formula.The analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) phase.The morphology of the hexaferrites was analyzed from the FESEM profiles of the ferrite samples.The magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.M,and Mossbauer spectroscopy,respectively.The hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the study.The substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.
文摘Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For the sample with active Cu as the top electrode,the formation and rupture of metallic Cu conductive filaments can explain the resistive switching behavior;for the other samples,the generation and annihilation of nitrogen vacancies under the electric stimuli may contribute to the occurrence of resistive switching.Taking advantage of the formed and broken Co-N bonds during resistive switching,the saturation magnetization of the BN-Co films can be modulated.Thus,it investigated the resistive switching behavior of BN and BN-Co materials in this work.Similar to that of oxide materials,the resistive switching behaviors of the nitrides may be attributed to the movement of cations or anions within the dielectric or electrodes during the application of voltage.Additionally,ion migration may lead to the formation or breaking of Co-N bonds,which can effectively regulate the magnetism of BN-Co materials.This study extends resistive switching materials to nitrides,enabling the regulation of magnetism along with resistance changes,thus providing insights for the design of novel voltage-controlled magnetic devices and achieving multi-functionality.
文摘Nowadays,there is considerable research interest in proposing modern permanent magnet(PM)electric machine structures for applications such as electric vehicles.Several radial and axial topologies with different arrangements of PM in the stator and rotor have been introduced for PM Vernier motors(PMVM)with the aim of increasing the performance characteristics such as power factor,efficiency,rotational torque torque density and wider constant torque-speed region.Meanwhile,the spoke PM arrangement has provided higher torque density than the surface and V-shaped arrangement.But in contrast,the V-shaped arrangement has a more sinusoidal flux and less cogging torque.In this paper,a 620 W,12-slot 16-pole Vernier PM motor with a fractional slot arrangement.Consequent K-shaped pole is introduced,which has the advantages of spoke and V-shaped magnetic arrangements.After presenting and confirming the concept of the proposed structure based on functional comparison with conventional structures,an analytical modeling based on the harmonic analysis method is introduced to accurately predict the performance of the machine,and finally the proposed structure is prototyped and the experimental results are simulated and modeling are compared.
基金supported by in part by the National Natural Science Foundation of China(62473387,52105079,62103455)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP241)。
文摘For permanent magnet synchronous machines(PMSMs),accurate machine model is critical for high performance maximum torque per ampere(MTPA)control.However,as motor speed increases,the nonlinearity such as core loss effect will affect the accuracy of machine model and thus the performance of online MTPA control.This paper firstly investigates the performance of the model based MTPA control under different motor speeds through modeling,simulation and experiments,which indicates that the accuracy of MTPA control is greatly reduced especially under high-speeds due to machine nonlinearity.Hence,this paper proposes an efficient nonlinearity compensation model based on polynomial fitting to model and compensate the MTPA error as motor speed increases.Considering both core loss and magnetic saturation effects,the compensation model is a nonlinear polynomial of speed and stator current.To obtain the fitting data,a derivative modeling method is proposed to compute the actual and detected MTPA angles under different speeds,in which the derivative model of torque to current ratio is fitted and the MTPA angle is obtained by setting the derivative model to zero.The proposed compensation model is both computation effective and easy to use for MTPA control,as it computes the compensation term that can be directly combined to other model-based methods.The proposed model is evaluated with experiments and comparisons on a test motor to show the performance improvement.
基金Project(13961001D)supported by the Key Basic Research Project of Hebei Province,ChinaProject(2013BAE08B01)supported by the National Key Technology R&D Program of China
文摘Fe75Zr3Si13B9 magnetic amorphous powders were fabricated by mechanical alloying. Bulk amorphous and nanocrystalline alloys with 20 mm in diameter and 7 mm in height were fabricated by the spark plasma sintering technology at different sintering temperatures. The phase composition, glass transition temperature （Tg）, onset crystallization temperature （Tx）, peak temperature （Tp） and super-cooled liquid region （ΔTx） of Fe75Zr3Si13B9 amorphous powders were analyzed by X-ray diffraction （XRD） and differential scanning calorimetry （DSC）. The phase transition, microstructure, mechanical properties and magnetic performance of the bulk alloys were discussed with X-ray diffractometer, scanning electron microscope （SEM）, Gleeble 3500 and vibration sample magnetometer （VSM）, respectively. It is found that with the increase in the sintering temperature at the pressure of 500 MPa, the density, compressive strength, micro-hardness and saturation magnetization of the sintering samples improved significantly, the amorphous phase began to crystallize gradually. Finally, the desirable amorphous and nanocrystalline magnetic materials at the sintering temperature of 863.15 K and the pressure of 500 MPa have a density of 6.9325 g/cm3, a compressive strength of 1140.28 MPa and a saturation magnetization of 1.28 T.
文摘The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.
文摘The effect of Mn substitution for partial Fe in RFe 11Ti on structure and magnetic properties of compounds was researched. RFe 7Mn 4Ti samples (R=Y,Tb,Dy,Ho,Er) were prepared by means of vacuum arc-melting and subsequent vacuum annealing. The structure and magnetic properties of RFe 7Mn 4Ti compounds were investigated by X-ray powder diffraction and magnetic measurements. The following conclusions were obtained: all the RFe tMn 4Ti compounds crystallize in the ThMn 12-type structure. The lattice constants and the unit-cell volume changed with the increase of atomic number for R=Y, Tb, Dy, Ho, and Er. The compensation characters appear for the DyFe 7Mn 4Ti and HoFe 7Mn 4Ti compounds, and the compensation temperatures were about 123 K and 90 K, respectively. The Curie temperature, the saturation magnetization, and saturation moment of RFe 7Mn 4Ti compounds were given.
基金Project supported by National Natural Science Foundation of China(51072163,51001085)
文摘Bi0.85La0.15FeO3 thin film was prepared on ATO glass substrates by sol-gel technique. The effect of La doping on phase structure, film surface quality, ion valence, and ferroelectric/magnetic properties of Bio.85La0.15FeO3 film were investigated. La doping suppressed the formation of impurity phases and the transition of Fe3＋ to Fe2＋ ions at room temperature. Compared with the un-doped BiFeO3, La-doping also increased the average grain size and the film density, which resulted in the decrease of film leakage current density. The remanent polarization and saturation magnetization were enhanced significantly by La doping. The remanent polariza- tion of Bi0.85La0.15FeO3 films gradually decreased while saturation magnetization increased with the decrease of measuring tempera- ture within a range from 50 to 300 K.
