With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are inve...With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are investigated with the Maxwell stress tensor method. Accurate results can easily be achieved using the proposed method without using the tedious finite element analysis (FEA). In this paper, the electromagnetic torque of a surface mounted PM motor with two phases energized is decomposed into four torque components. This technique is useful not only for the design and optimization of the permanent magnet motor, but also for the choice of control strategy.展开更多
Presents the mathematic model built for double stator permanent magnet synchronous motors through a brief analysis of their future development, and the equations established for calculation of their torques, and the d...Presents the mathematic model built for double stator permanent magnet synchronous motors through a brief analysis of their future development, and the equations established for calculation of their torques, and the development of prototypes, and discusses the comparison of the motor under development with the conventional motors with the same volume, stator structure, and magnet shape, and concludes the motor under development is one of the ways to improve the performance/volume ratio of motors.展开更多
The paper presents a mathematical multibody model of a soft mounted induction motor with sleeve bearings regarding forced vibrations caused by dynamic rotor eccentricities considering electromagnetic field damping. Th...The paper presents a mathematical multibody model of a soft mounted induction motor with sleeve bearings regarding forced vibrations caused by dynamic rotor eccentricities considering electromagnetic field damping. The multibody model contains the mass of the stator, rotor, shaft journals and bearing housings, the electromagnetic forces with respect of electromagnetic field damping, stiffness and internal (rotating) damping of the rotor, different kinds of dynamic rotor eccentricity, stiffness and damping of the bearing housings and end shields, stiffness and damping of the oil film of the sleeve bearings and stiffness and damping of the foundation. With this multibody model, the bearing housing vibrations and the relative shaft vibrations in the sleeve bearings can be derived.展开更多
The linear motor applied in electromagnetic emission system uses a closed loop position control strategy,which needs a set of position measurement system with high reliability,high resolution and integration to achiev...The linear motor applied in electromagnetic emission system uses a closed loop position control strategy,which needs a set of position measurement system with high reliability,high resolution and integration to achieve real-time acquisition and analysis of position signals.The existing position controller is based on the simple logic chip design without memory function,and does not have the storage analysis and preprocessing function to position signals.Therefore,the system has insufficient scalability,low integration and reliability.Aiming at the improvement of the existing position measurement system,an intelligent position measurement system integrating the functions of position signals acquisition,processing and uploading,data storage and analysis is proposed in this paper,and its working principle and system composition are discussed in detail.The position,speed and acceleration obtained on the electromagnetic emission platform are in good agreement with the expected value of the system.As results,the feasibility and accuracy of the improved integrated intelligent position measurement system are verified,and the control performance of the system is also satisfied well,which can be good guidance and reference for subsequent engineering practice.展开更多
Dynamic stability analysis of superconducting electro-dynamic maglev train under lateral and yawing motion condition is the key research content.The novel three-dimensional electromagnetic model of integrated linear s...Dynamic stability analysis of superconducting electro-dynamic maglev train under lateral and yawing motion condition is the key research content.The novel three-dimensional electromagnetic model of integrated linear synchronous motor in electro-dynamic maglev train with yawing operation condition is proposed,which can not only simultaneously achieve the propulsion,levitation and guidance performances of maglev vehicle,but also analyze the dynamic stability performance of train with yawing condition.The three-dimensional analytical method is introduced for analyzing the electromagnetic force characteristics of the linear synchronous motor with the yawing operation condition.Firstly,the topology structure and operation principle of the linear synchronous motor with yawing attitude are proposed.Secondly,the three-dimensional analytical model and expressions of electromagnetic characteristics are obtained by equivalent circuit method and Fourier decomposition method,such as levitation force,guidance force,propulsion force and yawing torque,etc.Finally,the three-dimensional electromagnetic characteristics of the linear synchronous motor are calculated under yawing operation conditions of maglev train,and the correctness of the analytical theory is verified by the finite element analysis and measured data on the test line.展开更多
In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D e...In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D electromagnetic field model of PMLSM is established. Special attention is paid to its structure and the influence of longitudinal and transverse end effect. The distribution of electromagnetic field of PMLSM can be obtained directly and promptly by using FFT algorithm. It can also be used for the analysis of other LSM.展开更多
Since the discovery of loadstone more than three hundred years ago, we have contemplated using the magnetic forces generated by permanent magnets to work for us. It is shown here that two permanent magnets with opposi...Since the discovery of loadstone more than three hundred years ago, we have contemplated using the magnetic forces generated by permanent magnets to work for us. It is shown here that two permanent magnets with opposite poles facing can attract along their equatorial plane and then repel along their polar plane in sequence, without reversing polarity and without the use of another source of energy. This sequence of attract and repel between two permanent magnets is like the attract and repel sequence between an electromagnet and permanent magnet in an electric motor. The discovery described here can be used to construct a motor driven entirely by permanent magnets.展开更多
A high thrust density linear motor,which adopts a novel toroidal structure,applying to load acceleration in confined space is proposed.The basic structure of the toroidal acceleration permanent magnet synchronous line...A high thrust density linear motor,which adopts a novel toroidal structure,applying to load acceleration in confined space is proposed.The basic structure of the toroidal acceleration permanent magnet synchronous linear motor(TA-PMLSM)is depicted,both with its parameters listed.The main characteristics such as air gap magnetic density and electromagnetic thrust are discussed by establishing the electromagnetic field equation in the cylindrical coordinate system.And simulation comparison between the Halbach permanent magnet array and the classical radial one is also made to get a higher density of the magnetic and electromagnetic thrust.Compared with the conventional radial permanent magnet array,results show that the amplitude of back EMF of ring motor under the action of Halbach permanent magnet array has a better sinusoidal,the magnetic density of the air gap increases by 1.3 times,the thrust density increases by 1.42 times,and the main harmonic content of the two referred physical quantity decreases significantly.展开更多
In this paper, we propose an electromagnetic-mechanical model based on the finite element and Macro-Element (ME) technique to analyse and study the dynamic characteristics of a Tubular Linear Switched Reluctance Stepp...In this paper, we propose an electromagnetic-mechanical model based on the finite element and Macro-Element (ME) technique to analyse and study the dynamic characteristics of a Tubular Linear Switched Reluctance Stepping Motor (LSRSM). After the resolution of the non-linear electromagnetic equation governing the behaviour of the different materials of the motor using the nodal-based finite element method, this equation is then coupled to the mechanical equation firstly through the magnetic force computed by Maxwell stress tensor, and secondly by the modified flux distribution due to the moving part. Because of the precision required in the mobile part displacement and the very small air gap of stepping motors, the simulation of the movement is assured by the Macro-Element (ME) technique compared to other movement techniques that present many disadvantages. The validity of the developed model is verified through the comparison of the computed displacement of the LSRSM moving part with those given experimentally [2]. The Results shows satisfactory agreement. The obtained dynamic characteristics, particularly the starting magnetic force, are obtained by considering two values of the supplying currents.展开更多
The operating speed of the commercial electromagnetic suspension(EMS)maglev train has been over 430 km/h,making it the fastest means of land transportation.With the increasing demands of people traveling,it is necessa...The operating speed of the commercial electromagnetic suspension(EMS)maglev train has been over 430 km/h,making it the fastest means of land transportation.With the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev trains.Aiming to examine whether the existing EMS system can meet the requirements of ultra-highspeed operation(more than 600 km/h),the electromagnetic characteristics of an EMS linear motor under the operating speed of 600–1000 km/h fed by a square-wave voltage supply is investigated in this article.First,an electromagnetic field model of the EMS system under the square-wave voltage supply is established to investigate its electromagnetic performance,e.g.,the characteristics of phase current,the magnetic flux density,and the electromagnetic force.Second,the relationship between the harmonic components of the air-gap magnetic flux density and electromagnetic force is investigated using the two-dimensional fast Fourier transform(2D-FFT)to reveal the mechanism of electromagnetic force ripple.Third,to address the issues of excessive armature current density and significant electromagnetic force ripple,the linear motor is re-designed by enlarging the stator slot area and reshaping the mover's main magnetic poles.Furthermore,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric motor.Finally,the effectiveness of the proposed optimal design is validated by the finite-element analysis(FEA)based co-simulation.展开更多
An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The can...An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. Mechanical and magnetic analysis are carried out on the actuator, and the device with a size of 2.2 mm × 2.5 mm is fabricated with the UV-LIGA technology. The test results show that a current pulse with an amplitude of 70 mA is needed for actuator' s switching between the two stable states, and the switching time is no more than 6 ms. Displacement of the end of cantilever is about 15 μm.展开更多
Objective This study aimed to investigate the effect of exposure to a 900 MHz electromagnetic field(EMF)on the cervical spinal cord(CSC)of rats and the possible protective effect of luteolin(LUT)against CSC tissue dam...Objective This study aimed to investigate the effect of exposure to a 900 MHz electromagnetic field(EMF)on the cervical spinal cord(CSC)of rats and the possible protective effect of luteolin(LUT)against CSC tissue damage.Methods Quantitative data were obtained via stereological,biochemical,immunohistochemical,and histopathological techniques.We investigated morphometric value,superoxide dismutase(SOD)level,and the expression of high-mobility group box 1 protein molecules,as well as histological changes.Results The total number of motor neurons in the EMF group significantly decreased in comparison with that in the control group(P<0.05).In the EMF+LUT group,we found a significant increase in the total number of motor neurons compared with that in the EMF group(P<0.05).SOD enzyme activity in the EMF group significantly increased in comparison with that in the control group(P<0.05).By contrast,the EMF+LUT group exhibited a decrease in SOD level compared with the EMF group(P<0.05).Conclusion Our results suggested that exposure to EMF could be deleterious to CSC tissues.Furthermore,the protective efficacy of LUT against SC damage might have resulted from the alleviation of oxidative stress caused by EMF.展开更多
Among the factors slowing down the production of the electric vehicles in big series, we mention the problem of weak autonomy directly bound to the weak storage capacity of the batteries. In this context, this paper d...Among the factors slowing down the production of the electric vehicles in big series, we mention the problem of weak autonomy directly bound to the weak storage capacity of the batteries. In this context, this paper describes a strategy of power chain vector control reducing the consumption and integrating a system of energy recuperation. Besides, this power chain is conceived by an analytic approach optimizing the autonomy and reducing the production cost of electric vehicle. The choice of the static converter to electromagnetic switches is a determining factor for the reliability of the global system and the reduction of the consumption. This choice poses a problem of adaptation of this low-frequency converter type to the global system that will be treated in this paper.展开更多
基金Project supported by the Science Foundation of Shanghai Municipal Commission of Education (Grant No.04AB30)
文摘With the air gap magnetic field distribution of surface mounted permanent magnet (PM) motors obtained using an analytical technique, the instantaneous electromagnetic torque and its corresponding components are investigated with the Maxwell stress tensor method. Accurate results can easily be achieved using the proposed method without using the tedious finite element analysis (FEA). In this paper, the electromagnetic torque of a surface mounted PM motor with two phases energized is decomposed into four torque components. This technique is useful not only for the design and optimization of the permanent magnet motor, but also for the choice of control strategy.
文摘Presents the mathematic model built for double stator permanent magnet synchronous motors through a brief analysis of their future development, and the equations established for calculation of their torques, and the development of prototypes, and discusses the comparison of the motor under development with the conventional motors with the same volume, stator structure, and magnet shape, and concludes the motor under development is one of the ways to improve the performance/volume ratio of motors.
文摘The paper presents a mathematical multibody model of a soft mounted induction motor with sleeve bearings regarding forced vibrations caused by dynamic rotor eccentricities considering electromagnetic field damping. The multibody model contains the mass of the stator, rotor, shaft journals and bearing housings, the electromagnetic forces with respect of electromagnetic field damping, stiffness and internal (rotating) damping of the rotor, different kinds of dynamic rotor eccentricity, stiffness and damping of the bearing housings and end shields, stiffness and damping of the oil film of the sleeve bearings and stiffness and damping of the foundation. With this multibody model, the bearing housing vibrations and the relative shaft vibrations in the sleeve bearings can be derived.
基金This work was supported in part by the National Natural Science Foundation of China(NSFC)under Grant 51507182 and 51477178.
文摘The linear motor applied in electromagnetic emission system uses a closed loop position control strategy,which needs a set of position measurement system with high reliability,high resolution and integration to achieve real-time acquisition and analysis of position signals.The existing position controller is based on the simple logic chip design without memory function,and does not have the storage analysis and preprocessing function to position signals.Therefore,the system has insufficient scalability,low integration and reliability.Aiming at the improvement of the existing position measurement system,an intelligent position measurement system integrating the functions of position signals acquisition,processing and uploading,data storage and analysis is proposed in this paper,and its working principle and system composition are discussed in detail.The position,speed and acceleration obtained on the electromagnetic emission platform are in good agreement with the expected value of the system.As results,the feasibility and accuracy of the improved integrated intelligent position measurement system are verified,and the control performance of the system is also satisfied well,which can be good guidance and reference for subsequent engineering practice.
基金supported in part by the National Natural Science Foundation of China under Grant 52077003 and 51777009。
文摘Dynamic stability analysis of superconducting electro-dynamic maglev train under lateral and yawing motion condition is the key research content.The novel three-dimensional electromagnetic model of integrated linear synchronous motor in electro-dynamic maglev train with yawing operation condition is proposed,which can not only simultaneously achieve the propulsion,levitation and guidance performances of maglev vehicle,but also analyze the dynamic stability performance of train with yawing condition.The three-dimensional analytical method is introduced for analyzing the electromagnetic force characteristics of the linear synchronous motor with the yawing operation condition.Firstly,the topology structure and operation principle of the linear synchronous motor with yawing attitude are proposed.Secondly,the three-dimensional analytical model and expressions of electromagnetic characteristics are obtained by equivalent circuit method and Fourier decomposition method,such as levitation force,guidance force,propulsion force and yawing torque,etc.Finally,the three-dimensional electromagnetic characteristics of the linear synchronous motor are calculated under yawing operation conditions of maglev train,and the correctness of the analytical theory is verified by the finite element analysis and measured data on the test line.
文摘In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D electromagnetic field model of PMLSM is established. Special attention is paid to its structure and the influence of longitudinal and transverse end effect. The distribution of electromagnetic field of PMLSM can be obtained directly and promptly by using FFT algorithm. It can also be used for the analysis of other LSM.
文摘Since the discovery of loadstone more than three hundred years ago, we have contemplated using the magnetic forces generated by permanent magnets to work for us. It is shown here that two permanent magnets with opposite poles facing can attract along their equatorial plane and then repel along their polar plane in sequence, without reversing polarity and without the use of another source of energy. This sequence of attract and repel between two permanent magnets is like the attract and repel sequence between an electromagnet and permanent magnet in an electric motor. The discovery described here can be used to construct a motor driven entirely by permanent magnets.
基金This work was supported in part by the National Key Laboratory Foundation of China under 6142217210505。
文摘A high thrust density linear motor,which adopts a novel toroidal structure,applying to load acceleration in confined space is proposed.The basic structure of the toroidal acceleration permanent magnet synchronous linear motor(TA-PMLSM)is depicted,both with its parameters listed.The main characteristics such as air gap magnetic density and electromagnetic thrust are discussed by establishing the electromagnetic field equation in the cylindrical coordinate system.And simulation comparison between the Halbach permanent magnet array and the classical radial one is also made to get a higher density of the magnetic and electromagnetic thrust.Compared with the conventional radial permanent magnet array,results show that the amplitude of back EMF of ring motor under the action of Halbach permanent magnet array has a better sinusoidal,the magnetic density of the air gap increases by 1.3 times,the thrust density increases by 1.42 times,and the main harmonic content of the two referred physical quantity decreases significantly.
文摘In this paper, we propose an electromagnetic-mechanical model based on the finite element and Macro-Element (ME) technique to analyse and study the dynamic characteristics of a Tubular Linear Switched Reluctance Stepping Motor (LSRSM). After the resolution of the non-linear electromagnetic equation governing the behaviour of the different materials of the motor using the nodal-based finite element method, this equation is then coupled to the mechanical equation firstly through the magnetic force computed by Maxwell stress tensor, and secondly by the modified flux distribution due to the moving part. Because of the precision required in the mobile part displacement and the very small air gap of stepping motors, the simulation of the movement is assured by the Macro-Element (ME) technique compared to other movement techniques that present many disadvantages. The validity of the developed model is verified through the comparison of the computed displacement of the LSRSM moving part with those given experimentally [2]. The Results shows satisfactory agreement. The obtained dynamic characteristics, particularly the starting magnetic force, are obtained by considering two values of the supplying currents.
基金supported by the National Key R&D Program of China(Grant No.2023YFB4302500)。
文摘The operating speed of the commercial electromagnetic suspension(EMS)maglev train has been over 430 km/h,making it the fastest means of land transportation.With the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev trains.Aiming to examine whether the existing EMS system can meet the requirements of ultra-highspeed operation(more than 600 km/h),the electromagnetic characteristics of an EMS linear motor under the operating speed of 600–1000 km/h fed by a square-wave voltage supply is investigated in this article.First,an electromagnetic field model of the EMS system under the square-wave voltage supply is established to investigate its electromagnetic performance,e.g.,the characteristics of phase current,the magnetic flux density,and the electromagnetic force.Second,the relationship between the harmonic components of the air-gap magnetic flux density and electromagnetic force is investigated using the two-dimensional fast Fourier transform(2D-FFT)to reveal the mechanism of electromagnetic force ripple.Third,to address the issues of excessive armature current density and significant electromagnetic force ripple,the linear motor is re-designed by enlarging the stator slot area and reshaping the mover's main magnetic poles.Furthermore,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric motor.Finally,the effectiveness of the proposed optimal design is validated by the finite-element analysis(FEA)based co-simulation.
基金Projece supported by National Natural Science Foundatin ofChina(Grant No .10377009)National High-Technology Researchand Development Program(Grant No .863 -2003AA404140) Science Foundation of National Information Industry Ministry ofChina(Grant No .41308050116)
文摘An electromagnetic microactuator with two stable positions is presented. The actuator consists of a cantilever beam with two free ends, a torsional beam with two fixed ends, planar coils and permanent magnets. The cantilever beam has two stable positions due to the use of permanent magnets. With electromagnetic actuation arising from the planar coils, the cantilever beam will switch from one stable position to the other. Mechanical and magnetic analysis are carried out on the actuator, and the device with a size of 2.2 mm × 2.5 mm is fabricated with the UV-LIGA technology. The test results show that a current pulse with an amplitude of 70 mA is needed for actuator' s switching between the two stable states, and the switching time is no more than 6 ms. Displacement of the end of cantilever is about 15 μm.
文摘Objective This study aimed to investigate the effect of exposure to a 900 MHz electromagnetic field(EMF)on the cervical spinal cord(CSC)of rats and the possible protective effect of luteolin(LUT)against CSC tissue damage.Methods Quantitative data were obtained via stereological,biochemical,immunohistochemical,and histopathological techniques.We investigated morphometric value,superoxide dismutase(SOD)level,and the expression of high-mobility group box 1 protein molecules,as well as histological changes.Results The total number of motor neurons in the EMF group significantly decreased in comparison with that in the control group(P<0.05).In the EMF+LUT group,we found a significant increase in the total number of motor neurons compared with that in the EMF group(P<0.05).SOD enzyme activity in the EMF group significantly increased in comparison with that in the control group(P<0.05).By contrast,the EMF+LUT group exhibited a decrease in SOD level compared with the EMF group(P<0.05).Conclusion Our results suggested that exposure to EMF could be deleterious to CSC tissues.Furthermore,the protective efficacy of LUT against SC damage might have resulted from the alleviation of oxidative stress caused by EMF.
文摘Among the factors slowing down the production of the electric vehicles in big series, we mention the problem of weak autonomy directly bound to the weak storage capacity of the batteries. In this context, this paper describes a strategy of power chain vector control reducing the consumption and integrating a system of energy recuperation. Besides, this power chain is conceived by an analytic approach optimizing the autonomy and reducing the production cost of electric vehicle. The choice of the static converter to electromagnetic switches is a determining factor for the reliability of the global system and the reduction of the consumption. This choice poses a problem of adaptation of this low-frequency converter type to the global system that will be treated in this paper.