A novel topology of modular ferrite magnet fluxswitching linear motor(FMFSLM)use for track transport is presented in this paper,which enables more ferrite magnets to be inserted into the primary iron core.The motor ha...A novel topology of modular ferrite magnet fluxswitching linear motor(FMFSLM)use for track transport is presented in this paper,which enables more ferrite magnets to be inserted into the primary iron core.The motor has a significant low-cost advantage in long-distance linear drive.The proposed FMFSLM’s structure and working principle were introduced.Further,the thrust force expression of the motor was established.The thrust force components triggering thrust force ripple were investigated,and their expressions can be obtained according to the inductances’Fourier series expressions.Resultantly,the relationship between the harmonics of thrust force and that of self-and mutual inductances was revealed clearly.Based on the relationship,a skewed secondary should be practical to reduce the thrust force ripple.Thus,the effect of employing a skewed secondary to the proposed FMFSLM was investigated,and an optimized skewing span distance was determined.Finite element analysis(FEA)was conducted to validate the exactness of the theoretical analysis.The simulation results indicate that the strategy of suppressing thrust force ripple has a significant effect.Meanwhile,the motor maintains a good efficiency characteristic.The results of the prototype experiment are in good agreement with FEAs,which further verifies the proposed modular interior FMFSLM’s practicability.展开更多
Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.T...Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.展开更多
A novel elevator door driven by tubular permanent magnet linear synchronous motor (TPMLSM) is presented. This TPMLSM applies axial magnet array topology of the secondary rod, air-cored armature windings and slotless s...A novel elevator door driven by tubular permanent magnet linear synchronous motor (TPMLSM) is presented. This TPMLSM applies axial magnet array topology of the secondary rod, air-cored armature windings and slotless structure of the forcer to improve the stability of the thrust. The influence of two major dimensions, the pitch and radius of the permanent magnet (PM), on magnetic field was studied and the best values were given by the finite element analysis (FEA). The magnetic field, back EMF and thrust of the motor were analyzed and the PM size was optimized to reduce the harmonic components of the magnetic field and improve the performance of the motor. Predicted results are validated by the experiment. It is shown that the performance of the motor and the novel elevator door system is satisfying.展开更多
In the linear induction motor control system,the optical grating speed transducer is susceptible to strong magnetic field interference.What's more,it may reduce motor integration and raise device costs.Therefore a...In the linear induction motor control system,the optical grating speed transducer is susceptible to strong magnetic field interference.What's more,it may reduce motor integration and raise device costs.Therefore a speed identification method to replace grating speed transducer is studied in this article.This speed identification method for linear induction motor mainly adopts Model Reference Adaptive Method(Abbreviated as MRAS)and Popov Hyperstability Theory.The research content of this paper can be divided into four parts.First,the mathematical model of the motor based on the model reference adaptive system structure is deduced.Second,the adaptive law of the estimated speed is solved by Popov hyper-stability theory,which ensures the stability of the system.Third,the simulation model of the linear induction motor speed identification control system based on model reference adaptation is built in the MATLAB environment.Finally,the simulation test and analysis are carried out.The simulation results show that the speed identification control system can track the actual speed of the linear induction motor well in the no-load operation and the load operation,and the stability of the system is guaranteed in the full speed range.展开更多
Linear induction motors are superior to rotary induction motors in direct drive systems because they can generate direct forward thrust force independent of mechanical transmission.However,due to the large air gap and...Linear induction motors are superior to rotary induction motors in direct drive systems because they can generate direct forward thrust force independent of mechanical transmission.However,due to the large air gap and cut-open magnetic circuit,their efficiency and power factor are quite low,which limit their application in high power drive systems.To attempt this challenge,this work presents a system-level optimization method for a single-sided linear induction motor drive system.Not only the motor but also the control system is included in the analysis.A system-level optimization method is employed to gain optimal steady-state and dynamic performances.To validate the effectiveness of the proposed optimization method,experimental results on a linear induction motor drive are presented and discussed.展开更多
Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping unit...Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.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
In this paper,a compound sliding mode velocity control scheme with a new exponential reaching law(NERL)with thrust ripple observation strategy is proposed to obtain a high performance velocity loop of the linear perma...In this paper,a compound sliding mode velocity control scheme with a new exponential reaching law(NERL)with thrust ripple observation strategy is proposed to obtain a high performance velocity loop of the linear permanent magnet synchronous motor(LPMSM)control system.A sliding mode velocity controller based on NERL is firstly discussed to restrain chattering of the conventional exponential reaching law(CERL).Furthermore,the unavoidable thrust ripple caused by the special structure of linear motor will bring about velocity fluctuation and reduced control performance.Thus,a thrust ripple compensation strategy on the basis of extend Kalman filter(EKF)theory is proposed.The estimated thrust ripple will be introduced into the sliding mode velocity controller to optimize the control accuracy and robustness.The effectiveness of the proposal is validated with experimental results.展开更多
A permanent magnet linear synchronous motor （PMLSM） for a high temperature superconducting （HTS） maglev system has been studied, including the motor structure, control strategy, and analysis techniques. Finite ele...A permanent magnet linear synchronous motor （PMLSM） for a high temperature superconducting （HTS） maglev system has been studied, including the motor structure, control strategy, and analysis techniques. Finite element analysis （FEA） of magnetic field is conducted to accurately calculate major motor parameters. Equivalent electrical circuit is used to predict the drive＇s steady-state characteristics, and a phase variable model is applied to predict the dynamic performance. Preliminary experiment with a prototype has been made to verify the theoretical analysis and the HTS-PM synchronous driving technology.展开更多
A new approach to speed control of induction motors is developed by introducing networked control systems （NCSs） into the induction motor driving system. The control strategy is to stabilize and track the rotor spee...A new approach to speed control of induction motors is developed by introducing networked control systems （NCSs） into the induction motor driving system. The control strategy is to stabilize and track the rotor speed of the induction motor when the network time delay occurs in the transport medium of network data. First, a feedback linearization method is used to achieve input-output linearization and decoupling control of the induction motor driving system based on rotor flux model, and then the characteristic of network data is analyzed in terms of the inherent network time delay. A networked control model of an induction motor is established. The sufficient condition of asymptotic stability for the networked induction motor driving system is given, and the state feedback controller is obtained by solving the linear matrix inequalities （LMIs）. Simulation results verify the efficiency of the proposed scheme.展开更多
In general, it is important to operate the; airgap length uniformly for improving the system efficiency independent of the flatness of the reaction plate in a railway propulsion system by a linear induction motor （LI...In general, it is important to operate the; airgap length uniformly for improving the system efficiency independent of the flatness of the reaction plate in a railway propulsion system by a linear induction motor （LIM）. And it is possible to operate the LIM propulsion system efficiently without a change of the LIM capacity through the airgap length control on the sloped rail. So, in this research, the authors introduce an airgap control system to control the airgap length which depends on the flatness of the secondary reaction plate when the LIM is operated, and design a rotary small-scaled LIM and its airgap control system before manufacturing the real system. Then, the authors analyze some characteristics of the LIM （thrust and normal force, input current, efficiency and power factor）, and through the LIM control modeling, the authors finally analyze an effect of the airgap-length control of the LIM by the airgap control system.展开更多
A linear ultrasonic motor using longitudinal vibration of bar with varying section is proposed. The lin- ear ultrasonic motor has two varying section bars connected by semi-circumferential structure. Elliptical trajec...A linear ultrasonic motor using longitudinal vibration of bar with varying section is proposed. The lin- ear ultrasonic motor has two varying section bars connected by semi-circumferential structure. Elliptical trajecto- ries of particles are formed on top of the semi-circumferential structure outer surface where a driving foot is locat- ed. And a mover is pushed to move linearly when the driving foot is pressed onto it. Finite element model of sta- tor is built and results of harmonic analysis verify its principle. Moreover, design requirements of the motor are analyzed through finite element analysis and the results of sensitive analysis provide an efficient way to design the type of linear ultrasonic motor. Prototype test shows that the motor can afford load of 10 N at the speed of 100 mm/s.展开更多
A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the b...A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the basic operational principle of the FSPMLM is introduced;and the magnetic fields at the two typical conditions of no-load are analyzed.Secondly,the FSPMLM is analyzed by the two-dimensional finite element method（FEM） to investigate the static electromagnetic characteristics such as flux-linkage,back EMF（electromotive force） and inductance performances.The cogging forces of two kinds of FSPMLMs with different shaped cores are analyzed and compared,and the results show that the cogging force is significantly reduced by using the E-shaped cores.Additionally,based on the co-energy method,the thrust equation is derived and verified by the simulation results obtained by the FEM.Finally,an experimental prototype is used to test the characteristics under open circuit and load conditions.The simulation and experimental results indicate that the proposed motor has advantages of a sinusoidal back-EMF waveform,a small cogging effect and a high thrust density,and it is suitable for the application of linear direct driving machine tools.展开更多
To guarantee the safety of the high speed maglev train system, a novel model based on the winding function theory is proposed for the long-stator linear synchronous motor（LSM）, which is suitable for the real-time ca...To guarantee the safety of the high speed maglev train system, a novel model based on the winding function theory is proposed for the long-stator linear synchronous motor（LSM）, which is suitable for the real-time calculation of the running state. The accurate coupled mathematical models under different internal fault conditions of the LSM are derived based on the normal model. Then the fault currents and electromagnetic forces are simulated and calculated for the major potential internal faults of the LSM, such as the single-phase short circuit, the phase-phase short circuit and the single-phase open circuit. The characteristic curve between the electromagnetic force and the armature current of the LSM, which is compared with the results from the finite element method, proves the validation of the proposed method. The fault rule is determined and the proposed analytical model also shows its feasibility in the fast fault diagnosis through the comparison of the simulation results of currents and electromagnetic forces under different internal fault types and short circuit ratios.展开更多
Various force disturbances influence the thrust force of linear motors when a linear motor （LM） is running. Among all of force disturbances, the force ripple is the dominant while a linear motor runs in low speed. I...Various force disturbances influence the thrust force of linear motors when a linear motor （LM） is running. Among all of force disturbances, the force ripple is the dominant while a linear motor runs in low speed. In order to suppress the force ripple, back propagation（BP） neural network is proposed to learn the function of the force ripple of linear motors, and the acquisition method of training samples is proposed based on a disturbance observer. An off-line BP neural network is used mainly because of its high running efficiency and the real-time requirement of the servo control system of a linear motor. By using the function, the force ripple is on-line compensated according to the position of the LM. The experimental results show that the force ripple is effectively suppressed by the compensation of the BP neural network.展开更多
Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing resear...Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of Kp and Ti on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor＇s motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature-axis current under typical load. Adaptive PI control strategy can effectively suppress the flat permanent magnet linear synchronous motor＇s vibration without affecting the motor＇s performance.展开更多
A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to ...A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.展开更多
Dynamic characteristic is presented by identifying the model and the dynamic parameters of a precise long stroke linear motor （PLSLM） with the air-bearing in optical lithography. The PLSLM is supported by air-bearin...Dynamic characteristic is presented by identifying the model and the dynamic parameters of a precise long stroke linear motor （PLSLM） with the air-bearing in optical lithography. The PLSLM is supported by air-bearing on the stator, and is driven by on-board two large linear motors in a cross-configuration. Firstly, a model of the PLSLM is established by finite element method （FEM）. Secondly, based on the model, the natural frequencies and model shapes are discusse＆ And the contribution of each active mode is evaluated by computing the modal participation factors （MPF）, which indicates the major vibration direction. Furthermore, by the experimental modal analysis, the experimental results are in agreement with simulation results, which it is sure that the FEM is reasonable. What＇s more, comparing with the effects on the frequency due to the air-bearing stiffness, the relations of the natural frequencies with the air-bearing stiffness are found. It is found that the frequency response curve is fluctuant with the air-bearing stiffness in each direction. Finally, it is conclusion that the natural frequency of the PLSLM is largely affected by the air-bearing stiffness variety. This research is contributed to the dynamic characteristics resulted from the air-beating stiffness. Further work will include better optimization on the dynamic parameter in the controller design through the control algorithm for the precise long stroke motor.展开更多
A contact model for describing the contact mechanics between the stator and slider of the standing wave linear ultrasonic motor was presented. The proposed model starts from the assumption that the vibration character...A contact model for describing the contact mechanics between the stator and slider of the standing wave linear ultrasonic motor was presented. The proposed model starts from the assumption that the vibration characteristics of the stator is not affected by the contact process. A modified friction models was used to analyze the contact problems. Firstly, the dynamic normal contact force, interface friction force, and steady-state characteristics were analyzed. Secondly, the influences of the contact layer material, the dynamic characteristics of the stator, and the pre-load on motor performance were simulated. Finally, to validate the contact model, a linear ultrasonic motor based on in-plane modes was used as an example. The corresponding results show that a set of simulation of motor performances based on the proposed contact mechanism is in good agreement with experimental results. This model is helpful to understanding the operation principle of the standing wave linear motor and thus contributes to the design of these types of motor.展开更多
Permanent magnet tubular linear motors(TLMs) arranged in multiple rows and multiple columns used for a radiotherapy machine were studied. Due to severe volumetric and thermal constraints, the TLMs were at high risk of...Permanent magnet tubular linear motors(TLMs) arranged in multiple rows and multiple columns used for a radiotherapy machine were studied. Due to severe volumetric and thermal constraints, the TLMs were at high risk of overheating. To predict the performance of the TLMs accurately, a multi-physics analysis approach was proposed. Specifically, it considered the coupling effects amongst the electromagnetic and the thermal models of the TLMs, as well as the fluid model of the surrounding air. To reduce computation cost, both the electromagnetic and the thermal models were based on lumped-parameter methods. Only a minimum set of numerical computation(computational fluid dynamics, CFD) was performed to model the complex fluid behavior. With the proposed approach, both steady state and transient state temperature distributions, thermal rating and permissible load can be predicted. The validity of this approach is verified through the experiment.展开更多
基金supported by Shandong Provincial Natural Science Foundation under Grant ZR2020ME205.
文摘A novel topology of modular ferrite magnet fluxswitching linear motor(FMFSLM)use for track transport is presented in this paper,which enables more ferrite magnets to be inserted into the primary iron core.The motor has a significant low-cost advantage in long-distance linear drive.The proposed FMFSLM’s structure and working principle were introduced.Further,the thrust force expression of the motor was established.The thrust force components triggering thrust force ripple were investigated,and their expressions can be obtained according to the inductances’Fourier series expressions.Resultantly,the relationship between the harmonics of thrust force and that of self-and mutual inductances was revealed clearly.Based on the relationship,a skewed secondary should be practical to reduce the thrust force ripple.Thus,the effect of employing a skewed secondary to the proposed FMFSLM was investigated,and an optimized skewing span distance was determined.Finite element analysis(FEA)was conducted to validate the exactness of the theoretical analysis.The simulation results indicate that the strategy of suppressing thrust force ripple has a significant effect.Meanwhile,the motor maintains a good efficiency characteristic.The results of the prototype experiment are in good agreement with FEAs,which further verifies the proposed modular interior FMFSLM’s practicability.
基金The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through Large Groups Project under grant number(RGP.2/111/43).
文摘Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.
基金Project (No. 50607016) supported by the National Natural ScienceFoundation of China
文摘A novel elevator door driven by tubular permanent magnet linear synchronous motor (TPMLSM) is presented. This TPMLSM applies axial magnet array topology of the secondary rod, air-cored armature windings and slotless structure of the forcer to improve the stability of the thrust. The influence of two major dimensions, the pitch and radius of the permanent magnet (PM), on magnetic field was studied and the best values were given by the finite element analysis (FEA). The magnetic field, back EMF and thrust of the motor were analyzed and the PM size was optimized to reduce the harmonic components of the magnetic field and improve the performance of the motor. Predicted results are validated by the experiment. It is shown that the performance of the motor and the novel elevator door system is satisfying.
基金supported in part by Natural Science Foundation for Innovative Groups of Hubei Province under grant 2018CFA008。
文摘In the linear induction motor control system,the optical grating speed transducer is susceptible to strong magnetic field interference.What's more,it may reduce motor integration and raise device costs.Therefore a speed identification method to replace grating speed transducer is studied in this article.This speed identification method for linear induction motor mainly adopts Model Reference Adaptive Method(Abbreviated as MRAS)and Popov Hyperstability Theory.The research content of this paper can be divided into four parts.First,the mathematical model of the motor based on the model reference adaptive system structure is deduced.Second,the adaptive law of the estimated speed is solved by Popov hyper-stability theory,which ensures the stability of the system.Third,the simulation model of the linear induction motor speed identification control system based on model reference adaptation is built in the MATLAB environment.Finally,the simulation test and analysis are carried out.The simulation results show that the speed identification control system can track the actual speed of the linear induction motor well in the no-load operation and the load operation,and the stability of the system is guaranteed in the full speed range.
文摘Linear induction motors are superior to rotary induction motors in direct drive systems because they can generate direct forward thrust force independent of mechanical transmission.However,due to the large air gap and cut-open magnetic circuit,their efficiency and power factor are quite low,which limit their application in high power drive systems.To attempt this challenge,this work presents a system-level optimization method for a single-sided linear induction motor drive system.Not only the motor but also the control system is included in the analysis.A system-level optimization method is employed to gain optimal steady-state and dynamic performances.To validate the effectiveness of the proposed optimization method,experimental results on a linear induction motor drive are presented and discussed.
文摘Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.
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 National Natural Science Foundation of China(52177194)in part by State Key Laboratory of Large Electric Drive System and Equipment Technology(SKLLDJ012016006)+1 种基金in part by Key Research and Development Project of ShaanXi Province(2019GY-060)in part by Key Laboratory of Industrial Automation in ShaanXi Province(SLGPT2019KF01-12)(。
文摘In this paper,a compound sliding mode velocity control scheme with a new exponential reaching law(NERL)with thrust ripple observation strategy is proposed to obtain a high performance velocity loop of the linear permanent magnet synchronous motor(LPMSM)control system.A sliding mode velocity controller based on NERL is firstly discussed to restrain chattering of the conventional exponential reaching law(CERL).Furthermore,the unavoidable thrust ripple caused by the special structure of linear motor will bring about velocity fluctuation and reduced control performance.Thus,a thrust ripple compensation strategy on the basis of extend Kalman filter(EKF)theory is proposed.The estimated thrust ripple will be introduced into the sliding mode velocity controller to optimize the control accuracy and robustness.The effectiveness of the proposal is validated with experimental results.
文摘A permanent magnet linear synchronous motor （PMLSM） for a high temperature superconducting （HTS） maglev system has been studied, including the motor structure, control strategy, and analysis techniques. Finite element analysis （FEA） of magnetic field is conducted to accurately calculate major motor parameters. Equivalent electrical circuit is used to predict the drive＇s steady-state characteristics, and a phase variable model is applied to predict the dynamic performance. Preliminary experiment with a prototype has been made to verify the theoretical analysis and the HTS-PM synchronous driving technology.
基金supported by National Natural Science Foundationof China (No. 69774011)
文摘A new approach to speed control of induction motors is developed by introducing networked control systems （NCSs） into the induction motor driving system. The control strategy is to stabilize and track the rotor speed of the induction motor when the network time delay occurs in the transport medium of network data. First, a feedback linearization method is used to achieve input-output linearization and decoupling control of the induction motor driving system based on rotor flux model, and then the characteristic of network data is analyzed in terms of the inherent network time delay. A networked control model of an induction motor is established. The sufficient condition of asymptotic stability for the networked induction motor driving system is given, and the state feedback controller is obtained by solving the linear matrix inequalities （LMIs）. Simulation results verify the efficiency of the proposed scheme.
文摘In general, it is important to operate the; airgap length uniformly for improving the system efficiency independent of the flatness of the reaction plate in a railway propulsion system by a linear induction motor （LIM）. And it is possible to operate the LIM propulsion system efficiently without a change of the LIM capacity through the airgap length control on the sloped rail. So, in this research, the authors introduce an airgap control system to control the airgap length which depends on the flatness of the secondary reaction plate when the LIM is operated, and design a rotary small-scaled LIM and its airgap control system before manufacturing the real system. Then, the authors analyze some characteristics of the LIM （thrust and normal force, input current, efficiency and power factor）, and through the LIM control modeling, the authors finally analyze an effect of the airgap-length control of the LIM by the airgap control system.
基金Supported by the National Natural Science Foundation of China(50735002)~~
文摘A linear ultrasonic motor using longitudinal vibration of bar with varying section is proposed. The lin- ear ultrasonic motor has two varying section bars connected by semi-circumferential structure. Elliptical trajecto- ries of particles are formed on top of the semi-circumferential structure outer surface where a driving foot is locat- ed. And a mover is pushed to move linearly when the driving foot is pressed onto it. Finite element model of sta- tor is built and results of harmonic analysis verify its principle. Moreover, design requirements of the motor are analyzed through finite element analysis and the results of sensitive analysis provide an efficient way to design the type of linear ultrasonic motor. Prototype test shows that the motor can afford load of 10 N at the speed of 100 mm/s.
文摘A novel flux-switching permanent magnet linear motor（FSPMLM） is proposed for linear direct driving machine tools.First,the two-and three-dimensional topological configuration of the proposed motor is presented;the basic operational principle of the FSPMLM is introduced;and the magnetic fields at the two typical conditions of no-load are analyzed.Secondly,the FSPMLM is analyzed by the two-dimensional finite element method（FEM） to investigate the static electromagnetic characteristics such as flux-linkage,back EMF（electromotive force） and inductance performances.The cogging forces of two kinds of FSPMLMs with different shaped cores are analyzed and compared,and the results show that the cogging force is significantly reduced by using the E-shaped cores.Additionally,based on the co-energy method,the thrust equation is derived and verified by the simulation results obtained by the FEM.Finally,an experimental prototype is used to test the characteristics under open circuit and load conditions.The simulation and experimental results indicate that the proposed motor has advantages of a sinusoidal back-EMF waveform,a small cogging effect and a high thrust density,and it is suitable for the application of linear direct driving machine tools.
文摘To guarantee the safety of the high speed maglev train system, a novel model based on the winding function theory is proposed for the long-stator linear synchronous motor（LSM）, which is suitable for the real-time calculation of the running state. The accurate coupled mathematical models under different internal fault conditions of the LSM are derived based on the normal model. Then the fault currents and electromagnetic forces are simulated and calculated for the major potential internal faults of the LSM, such as the single-phase short circuit, the phase-phase short circuit and the single-phase open circuit. The characteristic curve between the electromagnetic force and the armature current of the LSM, which is compared with the results from the finite element method, proves the validation of the proposed method. The fault rule is determined and the proposed analytical model also shows its feasibility in the fast fault diagnosis through the comparison of the simulation results of currents and electromagnetic forces under different internal fault types and short circuit ratios.
基金National Natural Science Foundation of China(No. 60474021)
文摘Various force disturbances influence the thrust force of linear motors when a linear motor （LM） is running. Among all of force disturbances, the force ripple is the dominant while a linear motor runs in low speed. In order to suppress the force ripple, back propagation（BP） neural network is proposed to learn the function of the force ripple of linear motors, and the acquisition method of training samples is proposed based on a disturbance observer. An off-line BP neural network is used mainly because of its high running efficiency and the real-time requirement of the servo control system of a linear motor. By using the function, the force ripple is on-line compensated according to the position of the LM. The experimental results show that the force ripple is effectively suppressed by the compensation of the BP neural network.
基金supported by National Science and Technology Major Projects of China (Grant Nos. 2011ZX04016-011,2009ZX04010-022)
文摘Due to low damping ratio, fiat permanent magnet linear synchronous motor＇s vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of Kp and Ti on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor＇s motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature-axis current under typical load. Adaptive PI control strategy can effectively suppress the flat permanent magnet linear synchronous motor＇s vibration without affecting the motor＇s performance.
基金Projects(51275235, 50975135) supported by the National Natural Science Foundation of ChinaProject(U0934004) supported by the Natural Science Foundation of Guangdong Province, ChinaProject(2011CB707602) supported by the National Basic Research Program of China
文摘A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.
基金National Basic Research Program of China (973 Program,No.2003CB716206)National Natural Science Foundation of China (No.50605025)
文摘Dynamic characteristic is presented by identifying the model and the dynamic parameters of a precise long stroke linear motor （PLSLM） with the air-bearing in optical lithography. The PLSLM is supported by air-bearing on the stator, and is driven by on-board two large linear motors in a cross-configuration. Firstly, a model of the PLSLM is established by finite element method （FEM）. Secondly, based on the model, the natural frequencies and model shapes are discusse＆ And the contribution of each active mode is evaluated by computing the modal participation factors （MPF）, which indicates the major vibration direction. Furthermore, by the experimental modal analysis, the experimental results are in agreement with simulation results, which it is sure that the FEM is reasonable. What＇s more, comparing with the effects on the frequency due to the air-bearing stiffness, the relations of the natural frequencies with the air-bearing stiffness are found. It is found that the frequency response curve is fluctuant with the air-bearing stiffness in each direction. Finally, it is conclusion that the natural frequency of the PLSLM is largely affected by the air-bearing stiffness variety. This research is contributed to the dynamic characteristics resulted from the air-beating stiffness. Further work will include better optimization on the dynamic parameter in the controller design through the control algorithm for the precise long stroke motor.
基金Funded by the National Basic Research Program (973 program) (No. 2011CB707602)the Digital Manufacturing Equipment and Technology National Key Laboratory,Huazhong University of Science and Technology (No. DMETKF2009002)National Sciences Foundation-Guangdong Natural Science Foundation,China (No.U0934004)
文摘A contact model for describing the contact mechanics between the stator and slider of the standing wave linear ultrasonic motor was presented. The proposed model starts from the assumption that the vibration characteristics of the stator is not affected by the contact process. A modified friction models was used to analyze the contact problems. Firstly, the dynamic normal contact force, interface friction force, and steady-state characteristics were analyzed. Secondly, the influences of the contact layer material, the dynamic characteristics of the stator, and the pre-load on motor performance were simulated. Finally, to validate the contact model, a linear ultrasonic motor based on in-plane modes was used as an example. The corresponding results show that a set of simulation of motor performances based on the proposed contact mechanism is in good agreement with experimental results. This model is helpful to understanding the operation principle of the standing wave linear motor and thus contributes to the design of these types of motor.
基金Project(2015BAI03B00)supported by the National Key Technology R&D Program of ChinaProject(Z141100000514015)supported by Science and Technology Planning Program of Beijing,ChinaProject(SKLT12A03)supported by Tribology Science Fund of State Key Laboratory of Tribology,China
文摘Permanent magnet tubular linear motors(TLMs) arranged in multiple rows and multiple columns used for a radiotherapy machine were studied. Due to severe volumetric and thermal constraints, the TLMs were at high risk of overheating. To predict the performance of the TLMs accurately, a multi-physics analysis approach was proposed. Specifically, it considered the coupling effects amongst the electromagnetic and the thermal models of the TLMs, as well as the fluid model of the surrounding air. To reduce computation cost, both the electromagnetic and the thermal models were based on lumped-parameter methods. Only a minimum set of numerical computation(computational fluid dynamics, CFD) was performed to model the complex fluid behavior. With the proposed approach, both steady state and transient state temperature distributions, thermal rating and permissible load can be predicted. The validity of this approach is verified through the experiment.
