This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by eleme...This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by elemental profile for 2020 and reciprocally REO consumption resolved by end market use.Differences are calculated relative to 2008 and presented as percentages and as absolute tonnage.These differences encompass both changes in relative sector demand and growth rate.Historical trends,global and U.S.for REO usage by sector are calculated for the period of 2018-2022.End market sector demands,as percentages are presented,referenced to United States Geological Survey(USGS)values from 2008.Attention is given to permanent magnets and associated elements given the growing renewable generation and vehicle electrification.The criticality of Nd and Dy are considered given that they are the foundation of NdFeB permanent magnets,prominent in electric vehicle traction motors and direct drive wind turbine generators.Economic activity associated with REE market sectors is presented.Notably usage does not reflect economic value.A prime example are catalysts versus magnets.Last,vast reserves of light and heavy REEs exist in coal and coal-byproducts with potential high impact upon critical REEs and associated economics.展开更多
The structure, magnetization, and magnetocrystalline anisotropy wereinvestigated using X-ray diffraction, vibrating sample magnetometer, and AC susceptibility-meter Itis found that the microstructure of (Sm_(0.5)Nd_(0...The structure, magnetization, and magnetocrystalline anisotropy wereinvestigated using X-ray diffraction, vibrating sample magnetometer, and AC susceptibility-meter Itis found that the microstructure of (Sm_(0.5)Nd_(0.5))_2(Fe_(1-x)Co_x)_(17) alloys is an(Sm,Nd)_2(Fe,Co)_(17) phase with the rhombohedral Th_2Zn_(17)-type structure. The Curie temperatureT_c increases with the Co concentration increasing, and the magnetization first increases as the Cocontent increases in (Sm_(0.5)Nd_(0.5))_2(Fe_(1-x)Co_x)_(17) alloys and then decreases slowly. Theeasy magnetization direction (EMD) of (Sm_(0.5)Nd_(0.5))_2(Fe_(0.25)Co_(0.75))_(17) is along thec-axis and a strong enhancement of the crystalline anisotropy energy constant K is produced by theaddition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and thendecreases slowly with the Co content further increasing. The(Sm_(0.5)Nd_(0.5))_2(Fe_(0.25)Co_(0.75))_(17) compound is an optical candidate for the new permanentmagnet, which possesses a high magnetization, a high Curie temperature, and a large anisotropy.展开更多
In the face of growing environmental pollution, developing a fuel-cell-driven shunting locomotive is a great challenge in China for environmental protection and energy saving, which combines the environmental advantag...In the face of growing environmental pollution, developing a fuel-cell-driven shunting locomotive is a great challenge in China for environmental protection and energy saving, which combines the environmental advantages of an electric locomotive with the lower infrastructure costs of a diesel-electric locomotive. In this paper, the investigation status and the development trend of the fuel-cell-driven shunting locomotive were introduced. Through innovation of the power system using fuel cells, an experiment prototype of a fuel-cell shunting locomotive was developed, which would reduce the effects on the environment of the existing locomotives. This was the first locomotive to use a proton exchange membrane fuel-cell （PEMFC） power plant in China. From October 2012, we started to test the fuel-cell power plant and further test runs on the test rail-line in Chengdu, Sichuan. The achieved encouraging results can provide fundamental data for the modification of the current individual fuel cell locomotives or further development of the fuel-cell hybrid ones in China.展开更多
This paper presents a novel non-singular fast terminal sliding mode control(NFTSMC)based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior mag...This paper presents a novel non-singular fast terminal sliding mode control(NFTSMC)based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior magnet synchronous motor(IPMSM)drive systems.The mathematical model of flux weakening(FW)control is established,and the deep flux weakening switching point is calculated accurately by analyzing the relationship between the torque curve and voltage decline curve.Next,a second-order NFTSMC is designed for the speed loop controller to ensure that the system converges to the equilibrium state in finite time.Then,an extended sliding mode disturbance observer(ESMDO)is designed to estimate the uncertainty of the system.Finally,compared with both the PI control and sliding mode control(SMC)by simulations and experiments with different working conditions,the method proposed has the merits of accelerating convergence,improving steady-state accuracy,and minimizing the current and torque pulsation.展开更多
This paper introduces the principle of space vector pulse width modulation （SVPWM）, and discusses a method for implementing the SVPWM based on MATLAB/SIMULINK, as well as modeling of AC servo system with permanent m...This paper introduces the principle of space vector pulse width modulation （SVPWM）, and discusses a method for implementing the SVPWM based on MATLAB/SIMULINK, as well as modeling of AC servo system with permanent magnet synchronous motor （PMSM）. Simulation results show that the model is effective, and the method provides a frame of reference for software and hardware designs which can be applied in high temperature superconducting （HTS） flywheel energy storage system （FESS） and linear motor （LM）.展开更多
The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In o...The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.展开更多
An adaptive repetitive control scheme is presented for a class of nonlinearly parameterized systems based on the fuzzy basis function network （FBFN）. The parameters of the fuzzy rules are tuned with adaptive schemes...An adaptive repetitive control scheme is presented for a class of nonlinearly parameterized systems based on the fuzzy basis function network （FBFN）. The parameters of the fuzzy rules are tuned with adaptive schemes. To attenuate chattering effectively, the discontinuous control term is approximated by an adaptive PI control structure. The bound of the discontinuous control term is assumed to be unknown and estimated by an adaptive mechanism. Based on the Lyapunov stability theory, an adaptive repetitive control law is proposed to guarantee the closed-loop stability and the tracking performance. By means of FBFNs, which avoid the nonlinear parameterization from entering into the adaptive repetitive control, the controller singularity problem is solved. The proposed approach does not require an exact structure of the system dynamics, and the proposed controller is utilized to control a model of permanent-magnet linear synchronous motor subject to significant disturbances and parameter uncertainties. The simulation results demonstrate the effectiveness of the proposed method.展开更多
The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdom...The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdomains,followed by rotor slots,air-gap,stator slots,PM,and external air-gap imported to account for flux leakage.The coil turns and the remanence of magnets are adjusted by keeping the magnetic and electrical loading on the motor constant.The distance between the centers of two adjacent stator slots varies due to the introduction of faulttolerant teeth.According to the variable separation method,the general solution expression of each region can be determined by solving the partial differential systems of equations.The magnetic field distributions of subdomains are obtained by applying the continuity conditions between adjacent regions.Some analytical field expressions are represented as new forms under armature reaction field condition compared to those under no-load condition.Based on the developed analytical models,the flux density distribution and the electromagnetic performance can be calculated under no-load or armature reaction field condition separately.The finite element analysis is carried out to verify the validity of the proposed analytical model.展开更多
基金Project supported by the United States Department of Energy,National Technology Laboratory through the NETL-Penn State University Coalition for Fossil Energy Research(UCFER 0007-PSU-DOE-6825,DE-FE0026285)。
文摘This article addresses the question of how the global and U.S.market sector allocations for rare earth elements compare.Accordingly,this article reports rare earth oxide(REO)market sector allocations,resolved by elemental profile for 2020 and reciprocally REO consumption resolved by end market use.Differences are calculated relative to 2008 and presented as percentages and as absolute tonnage.These differences encompass both changes in relative sector demand and growth rate.Historical trends,global and U.S.for REO usage by sector are calculated for the period of 2018-2022.End market sector demands,as percentages are presented,referenced to United States Geological Survey(USGS)values from 2008.Attention is given to permanent magnets and associated elements given the growing renewable generation and vehicle electrification.The criticality of Nd and Dy are considered given that they are the foundation of NdFeB permanent magnets,prominent in electric vehicle traction motors and direct drive wind turbine generators.Economic activity associated with REE market sectors is presented.Notably usage does not reflect economic value.A prime example are catalysts versus magnets.Last,vast reserves of light and heavy REEs exist in coal and coal-byproducts with potential high impact upon critical REEs and associated economics.
文摘The structure, magnetization, and magnetocrystalline anisotropy wereinvestigated using X-ray diffraction, vibrating sample magnetometer, and AC susceptibility-meter Itis found that the microstructure of (Sm_(0.5)Nd_(0.5))_2(Fe_(1-x)Co_x)_(17) alloys is an(Sm,Nd)_2(Fe,Co)_(17) phase with the rhombohedral Th_2Zn_(17)-type structure. The Curie temperatureT_c increases with the Co concentration increasing, and the magnetization first increases as the Cocontent increases in (Sm_(0.5)Nd_(0.5))_2(Fe_(1-x)Co_x)_(17) alloys and then decreases slowly. Theeasy magnetization direction (EMD) of (Sm_(0.5)Nd_(0.5))_2(Fe_(0.25)Co_(0.75))_(17) is along thec-axis and a strong enhancement of the crystalline anisotropy energy constant K is produced by theaddition of some Co atoms. The anisotropy energy constant reaches the maximum when x = 0.75 and thendecreases slowly with the Co content further increasing. The(Sm_(0.5)Nd_(0.5))_2(Fe_(0.25)Co_(0.75))_(17) compound is an optical candidate for the new permanentmagnet, which possesses a high magnetization, a high Curie temperature, and a large anisotropy.
基金supported by the National Natural Science Foundation of China (51177138)the Specialized Research Fund for the Doctoral Program of Higher Education (20100184110015)+3 种基金the International Science and Technology Cooperation and Exchange Research Plan of Sichuan Province (2012HH0007)the Science and Technology Development Plan of Ministry of Railways (2012J012-D)the Fundamental Research Funds for the Central Universities (SWJTU11CX030)the Specialized Research Fund for the Doctoral Program of Higher Education (20120184120011)
文摘In the face of growing environmental pollution, developing a fuel-cell-driven shunting locomotive is a great challenge in China for environmental protection and energy saving, which combines the environmental advantages of an electric locomotive with the lower infrastructure costs of a diesel-electric locomotive. In this paper, the investigation status and the development trend of the fuel-cell-driven shunting locomotive were introduced. Through innovation of the power system using fuel cells, an experiment prototype of a fuel-cell shunting locomotive was developed, which would reduce the effects on the environment of the existing locomotives. This was the first locomotive to use a proton exchange membrane fuel-cell （PEMFC） power plant in China. From October 2012, we started to test the fuel-cell power plant and further test runs on the test rail-line in Chengdu, Sichuan. The achieved encouraging results can provide fundamental data for the modification of the current individual fuel cell locomotives or further development of the fuel-cell hybrid ones in China.
基金supported by the Natural Science Foundation of China under Grant No.61733004the Scientific Research Fund of the Hunan Provincial Education Department under Grand No.18A267.
文摘This paper presents a novel non-singular fast terminal sliding mode control(NFTSMC)based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior magnet synchronous motor(IPMSM)drive systems.The mathematical model of flux weakening(FW)control is established,and the deep flux weakening switching point is calculated accurately by analyzing the relationship between the torque curve and voltage decline curve.Next,a second-order NFTSMC is designed for the speed loop controller to ensure that the system converges to the equilibrium state in finite time.Then,an extended sliding mode disturbance observer(ESMDO)is designed to estimate the uncertainty of the system.Finally,compared with both the PI control and sliding mode control(SMC)by simulations and experiments with different working conditions,the method proposed has the merits of accelerating convergence,improving steady-state accuracy,and minimizing the current and torque pulsation.
基金This workis supported by the Chinese High Technology Development Plan Projectunder Grant No. 2007AA03Z208.
文摘This paper introduces the principle of space vector pulse width modulation （SVPWM）, and discusses a method for implementing the SVPWM based on MATLAB/SIMULINK, as well as modeling of AC servo system with permanent magnet synchronous motor （PMSM）. Simulation results show that the model is effective, and the method provides a frame of reference for software and hardware designs which can be applied in high temperature superconducting （HTS） flywheel energy storage system （FESS） and linear motor （LM）.
基金Supported by National Natural Science Foundation of China(Grant No.51335009)Major National Science and Technology Project of China(Grant No.2011ZX04001-011)
文摘The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.
基金supported by the National Natural Science Foundation of China (61203041)the Chinese National Post-doctor Science Foundation (2011M500217)
文摘An adaptive repetitive control scheme is presented for a class of nonlinearly parameterized systems based on the fuzzy basis function network （FBFN）. The parameters of the fuzzy rules are tuned with adaptive schemes. To attenuate chattering effectively, the discontinuous control term is approximated by an adaptive PI control structure. The bound of the discontinuous control term is assumed to be unknown and estimated by an adaptive mechanism. Based on the Lyapunov stability theory, an adaptive repetitive control law is proposed to guarantee the closed-loop stability and the tracking performance. By means of FBFNs, which avoid the nonlinear parameterization from entering into the adaptive repetitive control, the controller singularity problem is solved. The proposed approach does not require an exact structure of the system dynamics, and the proposed controller is utilized to control a model of permanent-magnet linear synchronous motor subject to significant disturbances and parameter uncertainties. The simulation results demonstrate the effectiveness of the proposed method.
基金supported in part by the National Natural Science Foundation of China under Grants 51991383 and 52025073。
文摘The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdomains,followed by rotor slots,air-gap,stator slots,PM,and external air-gap imported to account for flux leakage.The coil turns and the remanence of magnets are adjusted by keeping the magnetic and electrical loading on the motor constant.The distance between the centers of two adjacent stator slots varies due to the introduction of faulttolerant teeth.According to the variable separation method,the general solution expression of each region can be determined by solving the partial differential systems of equations.The magnetic field distributions of subdomains are obtained by applying the continuity conditions between adjacent regions.Some analytical field expressions are represented as new forms under armature reaction field condition compared to those under no-load condition.Based on the developed analytical models,the flux density distribution and the electromagnetic performance can be calculated under no-load or armature reaction field condition separately.The finite element analysis is carried out to verify the validity of the proposed analytical model.
