With the development of high-frequency and highvoltagetraction machines(TM)incorporating hairpin windings(HW)and SiC inverters for electric vehicles(EV),both theinterturn voltage stress and temperature within HW are r...With the development of high-frequency and highvoltagetraction machines(TM)incorporating hairpin windings(HW)and SiC inverters for electric vehicles(EV),both theinterturn voltage stress and temperature within HW are rising,increasing the risk of partial discharge(PD),and presentingsignificant challenges to insulation safety.Therefore,this paperaddresses this issue and proposes potential solutions.Firstly,thepaper examines an 8-pole,48-slot,6-layer HW TM to highlightthe unique characteristics of this winding structure,and explainsthe uneven distribution of interturn voltage stress andtemperature.Subsequently,a high-frequency equivalent circuitmodel of the HW TM prototype is developed.The error ofsimulation and experiment is only 5.7%,which proves theaccuracy of the model.Then,an improved HW scheme isproposed to lower the maximum voltage stress by 29.3%.Furthermore,the temperature distribution of HW TM isanalyzed to facilitate a detailed examination of the impact oftemperature on insulation PD.Finally,the partial dischargeinception voltage(PDIV)of interturn insulation,consideringtemperature effects,is calculated and verified throughexperiment.The paper proposes a reliability-oriented designmethod and process for HW TM.It demonstrates that thereliability-oriented design can achieve PD-free performance inthe design stage of HW.展开更多
A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated fila...A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments with fiber tension are wound layer by layer,and consider the effects of accumulated stress and deformation during filament winding on the bursting strength of composite case.Taking∅520 mm composite cases as a case study,the filament-winding-process-induced stress and deformation as well as progressive damage behavior are numerically predicted,followed by a comparison with experimental results.The numerical results show that the predicted bursting pressures for composite cases manufactured on the mandrels with and without a flexible component are 14.20 MPa and 21.40 MPa,respectively.These values exhibit slight deviation from the measured pressures of 13.50 MPa and 21.57 MPa.Moreover,the predicted damage locations,situated respectively in the dome and cylinder,agree well with the experimental observation.These observations indicate that use of flexible component reduces the load-bearing capacity of the domes.Furthermore,it validates the reliability and accuracy of the proposed numerical method in predicting the bursting strength of composite cases.展开更多
High-speed permanent magnet synchronous motors(PMSMs)have recently been widely applied in various applications.However,due to the increased rotor speed and operating frequency increase,the winding AC losses rise subst...High-speed permanent magnet synchronous motors(PMSMs)have recently been widely applied in various applications.However,due to the increased rotor speed and operating frequency increase,the winding AC losses rise substantially,posing risks to the safety operation.Accurate modeling of the AC losses has therefore become critical at the motor initial design stage.This paper reviews the main modeling methods for AC copper losses in PMSMs,including analytical methods,finite element methods,and hybrid modeling methods.The advantages and disadvantages of each method are analyzed in detail,and key issues in the modeling process are discussed.Finally,future research directions in AC copper loss modeling are explored,providing new insights for motor design and performance optimization.展开更多
Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability.Meanwhile,fractional slot concentrated windings(FSCW)are...Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability.Meanwhile,fractional slot concentrated windings(FSCW)are well known because of short end winding length,simple structure,field weakening sufficiency,fault tolerant capability and higher slot fill factor.The five-phase machines equipped with FSCW,are very good candidates for the purpose of designing motors for high reliable applications,like electric cars,major transporting buses,high speed trains and massive trucks.But,in comparison to the general distributed windings,the FSCWs contain high magnetomotive force(MMF)space harmonic contents,which cause unwanted effects on the machine ability,such as localized iron saturation and core losses.This manuscript introduces several new five-phase fractional slot winding layouts,by the means of slot shifting concept in order to design the new types of synchronous reluctance motors(SynRels).In order to examine the proposed winding’s performances,three sample machines are designed as case studies,and analytical study and finite element analysis(FEA)is used for validation.展开更多
This paper proposes the application of high-voltage stator-cable windings in superconducting machines,based on the characteristics of strong magnetic fields and large air gaps.Cross-linked polyethylene cable winding c...This paper proposes the application of high-voltage stator-cable windings in superconducting machines,based on the characteristics of strong magnetic fields and large air gaps.Cross-linked polyethylene cable winding can be employed to achieve a rated voltage of 35 kV in direct-current(DC)-field superconducting machines,thereby enabling a direct connection between the superconducting machine and the power grid,eliminating the need for transformers.We first,through finite element analysis,demonstrate that the proposed high-voltage high-temperature superconducting machine not only meets the requirement of a 35 kV-rated voltage,but also exhibits minimal flux leakage,torque fluctuation,and harmonic distortion.We then compare three candidate types to discuss the tradeoff between the multi-group superconducting field winding arrangement and machine performances.We propose inverted trapezoidal superconducting field winding as a promising candidate,because it has minimal superconductivity material usage,the largest safety margin for the superconducting coils(SCs),low thrust ripple,and low total harmonic distortion with the desired 35 kV-rated voltage.Finally,through large-scale design parameter sweeping,we show how we selected the optimal parameters for field winding and validated them by the finite element method.展开更多
A winding system is a time-varying system that considers complex nonlinear characteristics,and how to control the stability of the winding tension during the winding process is the primary problem that has hindered de...A winding system is a time-varying system that considers complex nonlinear characteristics,and how to control the stability of the winding tension during the winding process is the primary problem that has hindered development in this field in recent years.Many nonlinear factors affect the tension in the winding process,such as friction,structured uncertainties,unstructured uncertainties,and external interference.These terms severely restrict the tension tracking performance.Existing tension control strategies are mainly based on the composite control of the tension and speed loops,and previous studies involve complex decoupling operations.Owing to the large number of calculations required for this method,it is inconvenient for practical engineering applications.To simplify the tension generation mechanism and the influence of the nonlinear characteristics of the winding system,a simpler nonlinear dynamic model of the winding tension was established.An adaptive method was applied to update the feedback gain of the continuous robust integral of the sign of the error(RISE).Furthermore,an extended state observer was used to estimate modeling errors and external disturbances.The model disturbance term can be compensated for in the designed RISE controller.The asymptotic stability of the system was proven according to the Lyapunov stability theory.Finally,a comparative analysis of the proposed nonlinear controller and several other controllers was performed.The results indicated that the control of the winding tension was significantly enhanced.展开更多
The magnetic flux in a permanent magnet transverse flux generator(PMTFG) is three-dimensional(3D), therefore, its efficacy is evaluated using 3D magnetic field analysis. Although the 3D finite-element method(FEM) is h...The magnetic flux in a permanent magnet transverse flux generator(PMTFG) is three-dimensional(3D), therefore, its efficacy is evaluated using 3D magnetic field analysis. Although the 3D finite-element method(FEM) is highly accurate and reliable for machine simulation, it requires a long computation time, which is crucial when it is to be used in an iterative optimization process. Therefore, an alternative to 3DFEM is required as a rapid and accurate analytical technique. This paper presents an analytical model for PMTFG analysis using winding function method. To obtain the air gap MMF distribution, the excitation magneto-motive force(MMF) and the turn function are determined based on certain assumptions. The magnetizing inductance, flux density, and back-electro-magnetomotive force of the winding are then determined. To assess the accuracy of the proposed method, the analytically calculated parameters of the generator are compared to those obtained by a 3D-FEM. The presented method requires significantly shorter computation time than the 3D-FEM with comparable accuracy.展开更多
Coal mine conveyor belt and other low-speed large torque system,the torque density and torque stability of the motor requirements are higher,permanent magnet/magnet reluctance hybrid rotor double stator synchronous mo...Coal mine conveyor belt and other low-speed large torque system,the torque density and torque stability of the motor requirements are higher,permanent magnet/magnet reluctance hybrid rotor double stator synchronous motor(PM/MRHRDSSM)is just adapted to this requirement,however,the traditional close winding single inverter vector control system control PM/MRHRDSSM provides large torque ripple,high speed fluctuation and large total harmonic distortion(THD)of the current,difficult to be used in actual production and life,this paper proposes a large torque open winding-permanent magnet/magnet reluctance hybrid rotor double stator synchronous motor(OW-PM/MRHRDSSM)based on SVPWM dual inverter control strategy,and analysis of open winding double inverter structure,and its voltage vector mathematical model,using the existing two-level inverter as a basis,the bilateral inverter separately discussed its role and control method,as well as the decomposition method of synthetic voltage vector and the inverter device in the small sector on-time,the end of this paper through simulation to compare the traditional close winding single inverter vector control system control PM/MRHRDSSM and the large torque OW-PM/MRHRDSSM based on SVPWM dual inverter control strategy to prove the effectiveness of the proposed method in reducing torque ripple,speed fluctuation and THD of current during motor operation.展开更多
The constant winding tension can make the filament arranged in order. The stress distribution between the filament balance fully gives play to the enhancement of filament, and increases the intensive workload of the c...The constant winding tension can make the filament arranged in order. The stress distribution between the filament balance fully gives play to the enhancement of filament, and increases the intensive workload of the composite winding material. This paper conducts the mechanical analysis for the unwinding roller and tension measuring roller of the cylindrical winding machine so that gets the mechanical model, gives error compensation formula caused by the radius change of the yarn group in the unwinding side, designs the closed-loop control system and utilizes the dynamical- integral PID control strategy to achieve the tension control during the process of the cylindrical winding.展开更多
Aimed at the S-elbow composed of two elbows with different radii, this article proposes a winding pattern design method combined with patch winding method and traditional winding method. It proposes an optimal combina...Aimed at the S-elbow composed of two elbows with different radii, this article proposes a winding pattern design method combined with patch winding method and traditional winding method. It proposes an optimal combination of calculating the tangential point amount and skip point amount to make the pattern distribution even and keep the minimal adjusting angle. The S-elbow overall winding pattem plan and simulation module are designed to verify the combined winding pattern design method and the calculation algorithm of the tangential point amount and skip point amount. From the pattern distribution and the simula- tion effect analysis, it shows that this combined winding pattern design method is a good solution to the S-elbow combined winding pattern design. Aimed at the S-elbow winding pattern based on the patch winding method, it carries out the precision error analysis and points out the correspondence between the error and mesh size. Generally speaking, the bigger the mesh size is, the quicker the program calculation speed is; the smaller the mesh size is, the smaller the winding pattern error is.展开更多
Based on the elastic theory of cylindrical shells and the theory of composite laminates,a prediction model for the residual prestress of the simplified round composite barrel for railgun is established.Only the fibre ...Based on the elastic theory of cylindrical shells and the theory of composite laminates,a prediction model for the residual prestress of the simplified round composite barrel for railgun is established.Only the fibre pretension is considered in this model.A three dimensional numerical simulation for the residual prestress in the railgun barrel is carried out,by combining the temperature differential method with the element birth and death technology.The results obtained by the two methods are compared.It reveals that the distribution trends of residual prestress are consistent.And the difference for residual prestress in the filament wound composite housing of barrel is relatively small.The same finite element method is used to analysis the residual prestress in the non-simplified composite barrels for railgun,which are under different control modes of winding tension.The results mean that the residual prestress in barrel will increase while the taper coefficient for winding is decreasing.Therefore,the sealing performance in bore is improved,but the strength of the filament wound composite housing drops.In addition,the axial and circumferential residual prestress in the filament wound composite housing with constant torque winding are close to the ones in iso-stress design for barrel.展开更多
The rectangular wire winding AC electrical machine has drawn extensive attention due to their high slot fill factor,good heat dissipation,strong rigidity and short end-windings,which can be potential candidates for so...The rectangular wire winding AC electrical machine has drawn extensive attention due to their high slot fill factor,good heat dissipation,strong rigidity and short end-windings,which can be potential candidates for some traction application so as to enhance torque density,improve efficiency,decrease vibration and weaken noise,etc.In this paper,based on the complex process craft and the electromagnetic performance,a comprehensive and systematical overview on the rectangular wire windings AC electrical machine is introduced.According to the process craft,the different type of the rectangular wire windings,the different inserting direction of the rectangular wire windings and the insulation structure have been compared and analyzed.Furthermore,the detailed rectangular wire windings connection is researched and the general design guideline has been concluded.Especially,the performance of rectangular wire windings AC machine has been presented,with emphasis on the measure of improving the bigger AC copper losses at the high speed condition due to the distinguished proximity and skin effects.Finally,the future trend of the rectangular wire windings AC electrical machine is prospected.展开更多
Based on the multi-loop method, the rotating torque and speed of theinduction machine are analyzed. The fluctuating components of the torque and speed caused by rotorwinding faults are studied. The models for calculat...Based on the multi-loop method, the rotating torque and speed of theinduction machine are analyzed. The fluctuating components of the torque and speed caused by rotorwinding faults are studied. The models for calculating the fluctuating components are put forward.Simulation and computation results show that the rotor winding faults will cause electromagnetictorque and rotating speed to fluctuate; and fluctuating frequencies are the same and their magnitudewill increase with the rise of the severity of the faults. The load inertia affects the torque andspeed fluctuation, with the increase of inertia, the fluctuation of the torque will rise, while thecorresponding speed fluctuation will obviously decline.展开更多
The KTX device is a reversed field pinch （RFP） device currently under construction. Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms. Its major radius is 1.4 m and its minor ra...The KTX device is a reversed field pinch （RFP） device currently under construction. Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms. Its major radius is 1.4 m and its minor radius is 0.55 m. One of the most important problems in the magnet system design is how to reduce the TF magnetic field ripple and error field. A new wedge- shaped TF coil is put forward for the KTX device and its electromagnetic properties are compared with those of rectangular-shaped TF coils. The error field B,I/Bt of wedge-shaped TF coils with 6.4 degrees is about 6% as compared with 8% in the case of a rectangular-shaped TF coil. Besides, the wedge-shaped TF coils have a lower magnetic field ripple at the edge of the plasma region, which is smaller than 7.5% at R=1.83 m and 2% at R=l.07 m. This means that the tokamak operation mode may be feasible for this device when the plasma area becomes smaller, because the maximum ripple in the plasma area of the tokamak model is always required to be smaller than 0.4%. Detailed analysis of the results shows that the structure of the wedged-shape TF coil is reliable. It can serve as a reference for TF coil design of small aspect ratio RFPs or similar torus devices.展开更多
A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathemat...A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathematical model and transfer function are presented based on mechanism of the winding/unwinding control system.Simulation of the fuzzy controller carried out in the MATLAB(Simulink)environment proves that the control system based on fuzzy controller is superior in quality,precision and operation to a conventional optimal PID controller.The outlined experimental results also show the effectiveness and the robustness of the fuzzy PID controller in good dynamic performance,high robustness to parameter variation and disturbance.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
The pattern for filament wound toroidal vessels derived from differential geometry is presented. The pattern design and optimization procedure was put forward according to imposed design requirements. The mathematical...The pattern for filament wound toroidal vessels derived from differential geometry is presented. The pattern design and optimization procedure was put forward according to imposed design requirements. The mathematical model and movement equations of winding torns are obtained by analytic geometry. A computer simulation system of filament winding process based on optimal pattern design was developed to verify the correctness and practicability of the winding pattern. The optimum pattern and winding simulation were performed by this system. The simulation results show that the pattern satisfies both winding principles and structural optimization. The recommended design-oriented method can be applied to the preliminary design of filament wound toroidal vessels.展开更多
Non-Hermitian(NH)systems have revealed unique topological phenomena that are not observed in Hermitian counterparts,such as novel topology classifications and the NH skin effect.In periodic NH systems,eigenenergies be...Non-Hermitian(NH)systems have revealed unique topological phenomena that are not observed in Hermitian counterparts,such as novel topology classifications and the NH skin effect.In periodic NH systems,eigenenergies become complex and exhibit windings in the complex plane,while eigenstate winding numbers,which are strictly integers in Hermitian systems,can take half-integer values.However,direct experimental observation of NH winding of both eigenenergies and eigenstates,especially the half-integer winding,remains a significant challenge.In this work,we utilize the orbital angular momentum(OAM)synthetic dimension to construct an NH topological lattice and achieve direct observation of both eigenstate and eigenenergy windings.We report the first experimental observation of a half-integer eigenstate winding number,and reveal the intrinsic relationship between the direction in the NH skin dynamics and eigenenergy windings.Furthermore,by partitioning the OAM chain into two semi-infinite chains,we observe zero boundary modes and demonstrate that their distributions are jointly determined by the winding numbers of both the eigenstates and eigenenergies.This work provides comprehensive insights into NH topologies and offers a new experimental platform for exploring NH phenomena.展开更多
Transition metal phosphides(TMPs)are recognized as such promising supercapacitor materials for the practical application,due to their superior electrical conductivity and excellent redox activity.Here,self-supported t...Transition metal phosphides(TMPs)are recognized as such promising supercapacitor materials for the practical application,due to their superior electrical conductivity and excellent redox activity.Here,self-supported three-dimensional NiCoP nanoparticles embedded in NiCoO2 nano wires(NiCoO2/NiCoP)electrode consisting of nickel cobalt phosphides(NiCoP)with high activity and nickel cobalt oxides(NiCoO2)with good stability were fabricated by a hydrothermal and phosphorization method.The electrode integrates the advantages of nanowire arrays for fast ion transport and foam Ni for effective charge transport and flexibility.Benefitting the proper composition control of the nanohybrid and unique structure design,the optimized NiCoO2/NiCoP-20 exhibits a high specific capacitance of 3204 F·g-1 at 1 A·g-1 in 3 mol·L-1 KOH aqueous electrolyte in a three-electrode system.Moreover,the asymmetric supercapacitor assembled with the prepared NiCoO2/NiCoP-20 and activated carbon achieves a specific capacitance of 116 F·g-1 with a high energy density of 40.32 Wh·kg-1 at the power density of 800.18 W·kg-1.The practical application is further demonstrated with all-solid-state winding supercapacitor devices,with decent flexibility,in series to light the Central South University(CSU)logo consisting of 21 red LED indicators.展开更多
Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical f...Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical fiber free end has been made and balance equation of infinitesimal fiber is deduced, then deformation equation is derived by substituting terminal conditions. On condition that only axial tensile force exists, approximate curve equation has been built in small angle deformation scope. The comparison of tangent point longitudinal coordinate result between theory and approximation gives constant of integration, and expression with tangent point as origin of coordinate is readjusted. Analyzing the winding parameters of an example, it is clear that the horizontal distance from the highest point of wheel to fiber tangent point has millimeter order of magnitude and significant difference with fiber tension variation, and maintains invariant when wheel radius changes. The height of tension and accurate position of tangent point are defined for proper fiber guide. For application to fiber optic gyroscope, spiral-disc winding method and nonideal deformation of straddle section are analyzed, and then spiral-disc quadrupole pattern winding method has been introduced and realized by winding system. The winding results approve that the winding model is applicable.展开更多
基金supported by the Project of National Natural Science Foundation of China under Grant 52407060 and 52422704supported by Liaoning Province science and technology plan doctoral project under Grant 2023-BSBA-255.
文摘With the development of high-frequency and highvoltagetraction machines(TM)incorporating hairpin windings(HW)and SiC inverters for electric vehicles(EV),both theinterturn voltage stress and temperature within HW are rising,increasing the risk of partial discharge(PD),and presentingsignificant challenges to insulation safety.Therefore,this paperaddresses this issue and proposes potential solutions.Firstly,thepaper examines an 8-pole,48-slot,6-layer HW TM to highlightthe unique characteristics of this winding structure,and explainsthe uneven distribution of interturn voltage stress andtemperature.Subsequently,a high-frequency equivalent circuitmodel of the HW TM prototype is developed.The error ofsimulation and experiment is only 5.7%,which proves theaccuracy of the model.Then,an improved HW scheme isproposed to lower the maximum voltage stress by 29.3%.Furthermore,the temperature distribution of HW TM isanalyzed to facilitate a detailed examination of the impact oftemperature on insulation PD.Finally,the partial dischargeinception voltage(PDIV)of interturn insulation,consideringtemperature effects,is calculated and verified throughexperiment.The paper proposes a reliability-oriented designmethod and process for HW TM.It demonstrates that thereliability-oriented design can achieve PD-free performance inthe design stage of HW.
基金supported by the National Natural Science Foundation of China(No.11902231)the Major Program(JD)of Hubei Province,China(No.2023BAA004).
文摘A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed here.This method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments with fiber tension are wound layer by layer,and consider the effects of accumulated stress and deformation during filament winding on the bursting strength of composite case.Taking∅520 mm composite cases as a case study,the filament-winding-process-induced stress and deformation as well as progressive damage behavior are numerically predicted,followed by a comparison with experimental results.The numerical results show that the predicted bursting pressures for composite cases manufactured on the mandrels with and without a flexible component are 14.20 MPa and 21.40 MPa,respectively.These values exhibit slight deviation from the measured pressures of 13.50 MPa and 21.57 MPa.Moreover,the predicted damage locations,situated respectively in the dome and cylinder,agree well with the experimental observation.These observations indicate that use of flexible component reduces the load-bearing capacity of the domes.Furthermore,it validates the reliability and accuracy of the proposed numerical method in predicting the bursting strength of composite cases.
基金supported in part by the National Natural Science Foundation of China under Grants 52025073 and 52377055。
文摘High-speed permanent magnet synchronous motors(PMSMs)have recently been widely applied in various applications.However,due to the increased rotor speed and operating frequency increase,the winding AC losses rise substantially,posing risks to the safety operation.Accurate modeling of the AC losses has therefore become critical at the motor initial design stage.This paper reviews the main modeling methods for AC copper losses in PMSMs,including analytical methods,finite element methods,and hybrid modeling methods.The advantages and disadvantages of each method are analyzed in detail,and key issues in the modeling process are discussed.Finally,future research directions in AC copper loss modeling are explored,providing new insights for motor design and performance optimization.
文摘Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability.Meanwhile,fractional slot concentrated windings(FSCW)are well known because of short end winding length,simple structure,field weakening sufficiency,fault tolerant capability and higher slot fill factor.The five-phase machines equipped with FSCW,are very good candidates for the purpose of designing motors for high reliable applications,like electric cars,major transporting buses,high speed trains and massive trucks.But,in comparison to the general distributed windings,the FSCWs contain high magnetomotive force(MMF)space harmonic contents,which cause unwanted effects on the machine ability,such as localized iron saturation and core losses.This manuscript introduces several new five-phase fractional slot winding layouts,by the means of slot shifting concept in order to design the new types of synchronous reluctance motors(SynRels).In order to examine the proposed winding’s performances,three sample machines are designed as case studies,and analytical study and finite element analysis(FEA)is used for validation.
基金State Grid Corporation of China R&D Project(No.5500-202319193A-1-1-ZN).
文摘This paper proposes the application of high-voltage stator-cable windings in superconducting machines,based on the characteristics of strong magnetic fields and large air gaps.Cross-linked polyethylene cable winding can be employed to achieve a rated voltage of 35 kV in direct-current(DC)-field superconducting machines,thereby enabling a direct connection between the superconducting machine and the power grid,eliminating the need for transformers.We first,through finite element analysis,demonstrate that the proposed high-voltage high-temperature superconducting machine not only meets the requirement of a 35 kV-rated voltage,but also exhibits minimal flux leakage,torque fluctuation,and harmonic distortion.We then compare three candidate types to discuss the tradeoff between the multi-group superconducting field winding arrangement and machine performances.We propose inverted trapezoidal superconducting field winding as a promising candidate,because it has minimal superconductivity material usage,the largest safety margin for the superconducting coils(SCs),low thrust ripple,and low total harmonic distortion with the desired 35 kV-rated voltage.Finally,through large-scale design parameter sweeping,we show how we selected the optimal parameters for field winding and validated them by the finite element method.
基金Supported by National Key R&D Program of China (Grant No.2018YFB2000702)National Natural Science Foundation of China (Grant No.52075262)Fok Ying-Tong Education Foundation of China (Grant No.171044)。
文摘A winding system is a time-varying system that considers complex nonlinear characteristics,and how to control the stability of the winding tension during the winding process is the primary problem that has hindered development in this field in recent years.Many nonlinear factors affect the tension in the winding process,such as friction,structured uncertainties,unstructured uncertainties,and external interference.These terms severely restrict the tension tracking performance.Existing tension control strategies are mainly based on the composite control of the tension and speed loops,and previous studies involve complex decoupling operations.Owing to the large number of calculations required for this method,it is inconvenient for practical engineering applications.To simplify the tension generation mechanism and the influence of the nonlinear characteristics of the winding system,a simpler nonlinear dynamic model of the winding tension was established.An adaptive method was applied to update the feedback gain of the continuous robust integral of the sign of the error(RISE).Furthermore,an extended state observer was used to estimate modeling errors and external disturbances.The model disturbance term can be compensated for in the designed RISE controller.The asymptotic stability of the system was proven according to the Lyapunov stability theory.Finally,a comparative analysis of the proposed nonlinear controller and several other controllers was performed.The results indicated that the control of the winding tension was significantly enhanced.
文摘The magnetic flux in a permanent magnet transverse flux generator(PMTFG) is three-dimensional(3D), therefore, its efficacy is evaluated using 3D magnetic field analysis. Although the 3D finite-element method(FEM) is highly accurate and reliable for machine simulation, it requires a long computation time, which is crucial when it is to be used in an iterative optimization process. Therefore, an alternative to 3DFEM is required as a rapid and accurate analytical technique. This paper presents an analytical model for PMTFG analysis using winding function method. To obtain the air gap MMF distribution, the excitation magneto-motive force(MMF) and the turn function are determined based on certain assumptions. The magnetizing inductance, flux density, and back-electro-magnetomotive force of the winding are then determined. To assess the accuracy of the proposed method, the analytically calculated parameters of the generator are compared to those obtained by a 3D-FEM. The presented method requires significantly shorter computation time than the 3D-FEM with comparable accuracy.
基金supported in part by the National Natural Science Foundation of China under Grant U22A20215 and 51877139Applied Basic Research Program of Liaoning Province under Grant 2023JH2/101300219。
文摘Coal mine conveyor belt and other low-speed large torque system,the torque density and torque stability of the motor requirements are higher,permanent magnet/magnet reluctance hybrid rotor double stator synchronous motor(PM/MRHRDSSM)is just adapted to this requirement,however,the traditional close winding single inverter vector control system control PM/MRHRDSSM provides large torque ripple,high speed fluctuation and large total harmonic distortion(THD)of the current,difficult to be used in actual production and life,this paper proposes a large torque open winding-permanent magnet/magnet reluctance hybrid rotor double stator synchronous motor(OW-PM/MRHRDSSM)based on SVPWM dual inverter control strategy,and analysis of open winding double inverter structure,and its voltage vector mathematical model,using the existing two-level inverter as a basis,the bilateral inverter separately discussed its role and control method,as well as the decomposition method of synthetic voltage vector and the inverter device in the small sector on-time,the end of this paper through simulation to compare the traditional close winding single inverter vector control system control PM/MRHRDSSM and the large torque OW-PM/MRHRDSSM based on SVPWM dual inverter control strategy to prove the effectiveness of the proposed method in reducing torque ripple,speed fluctuation and THD of current during motor operation.
文摘The constant winding tension can make the filament arranged in order. The stress distribution between the filament balance fully gives play to the enhancement of filament, and increases the intensive workload of the composite winding material. This paper conducts the mechanical analysis for the unwinding roller and tension measuring roller of the cylindrical winding machine so that gets the mechanical model, gives error compensation formula caused by the radius change of the yarn group in the unwinding side, designs the closed-loop control system and utilizes the dynamical- integral PID control strategy to achieve the tension control during the process of the cylindrical winding.
基金National Natural Science Foundation of China (50905088)Science and Technoloy Major Project (2009ZX04004-102)
文摘Aimed at the S-elbow composed of two elbows with different radii, this article proposes a winding pattern design method combined with patch winding method and traditional winding method. It proposes an optimal combination of calculating the tangential point amount and skip point amount to make the pattern distribution even and keep the minimal adjusting angle. The S-elbow overall winding pattem plan and simulation module are designed to verify the combined winding pattern design method and the calculation algorithm of the tangential point amount and skip point amount. From the pattern distribution and the simula- tion effect analysis, it shows that this combined winding pattern design method is a good solution to the S-elbow combined winding pattern design. Aimed at the S-elbow winding pattern based on the patch winding method, it carries out the precision error analysis and points out the correspondence between the error and mesh size. Generally speaking, the bigger the mesh size is, the quicker the program calculation speed is; the smaller the mesh size is, the smaller the winding pattern error is.
文摘Based on the elastic theory of cylindrical shells and the theory of composite laminates,a prediction model for the residual prestress of the simplified round composite barrel for railgun is established.Only the fibre pretension is considered in this model.A three dimensional numerical simulation for the residual prestress in the railgun barrel is carried out,by combining the temperature differential method with the element birth and death technology.The results obtained by the two methods are compared.It reveals that the distribution trends of residual prestress are consistent.And the difference for residual prestress in the filament wound composite housing of barrel is relatively small.The same finite element method is used to analysis the residual prestress in the non-simplified composite barrels for railgun,which are under different control modes of winding tension.The results mean that the residual prestress in barrel will increase while the taper coefficient for winding is decreasing.Therefore,the sealing performance in bore is improved,but the strength of the filament wound composite housing drops.In addition,the axial and circumferential residual prestress in the filament wound composite housing with constant torque winding are close to the ones in iso-stress design for barrel.
基金This work was supported by the National Nature Science Foundation of China(NSFC)under Project 51607079.
文摘The rectangular wire winding AC electrical machine has drawn extensive attention due to their high slot fill factor,good heat dissipation,strong rigidity and short end-windings,which can be potential candidates for some traction application so as to enhance torque density,improve efficiency,decrease vibration and weaken noise,etc.In this paper,based on the complex process craft and the electromagnetic performance,a comprehensive and systematical overview on the rectangular wire windings AC electrical machine is introduced.According to the process craft,the different type of the rectangular wire windings,the different inserting direction of the rectangular wire windings and the insulation structure have been compared and analyzed.Furthermore,the detailed rectangular wire windings connection is researched and the general design guideline has been concluded.Especially,the performance of rectangular wire windings AC machine has been presented,with emphasis on the measure of improving the bigger AC copper losses at the high speed condition due to the distinguished proximity and skin effects.Finally,the future trend of the rectangular wire windings AC electrical machine is prospected.
文摘Based on the multi-loop method, the rotating torque and speed of theinduction machine are analyzed. The fluctuating components of the torque and speed caused by rotorwinding faults are studied. The models for calculating the fluctuating components are put forward.Simulation and computation results show that the rotor winding faults will cause electromagnetictorque and rotating speed to fluctuate; and fluctuating frequencies are the same and their magnitudewill increase with the rise of the severity of the faults. The load inertia affects the torque andspeed fluctuation, with the increase of inertia, the fluctuation of the torque will rise, while thecorresponding speed fluctuation will obviously decline.
基金supported by the National ITER Special Support for R&D on Science and Technology for ITER,"Research on Reversed Field Pinch Magnetic Confinement Configuration",CN Schedule Task(No.2011GB106000)
文摘The KTX device is a reversed field pinch （RFP） device currently under construction. Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms. Its major radius is 1.4 m and its minor radius is 0.55 m. One of the most important problems in the magnet system design is how to reduce the TF magnetic field ripple and error field. A new wedge- shaped TF coil is put forward for the KTX device and its electromagnetic properties are compared with those of rectangular-shaped TF coils. The error field B,I/Bt of wedge-shaped TF coils with 6.4 degrees is about 6% as compared with 8% in the case of a rectangular-shaped TF coil. Besides, the wedge-shaped TF coils have a lower magnetic field ripple at the edge of the plasma region, which is smaller than 7.5% at R=1.83 m and 2% at R=l.07 m. This means that the tokamak operation mode may be feasible for this device when the plasma area becomes smaller, because the maximum ripple in the plasma area of the tokamak model is always required to be smaller than 0.4%. Detailed analysis of the results shows that the structure of the wedged-shape TF coil is reliable. It can serve as a reference for TF coil design of small aspect ratio RFPs or similar torus devices.
文摘A fuzzy controller of the winding/unwinding control system used in jig-dyeing machine is introduced,which is superior to the one with conventional optimal PID controller in convergence speed and stability.Its mathematical model and transfer function are presented based on mechanism of the winding/unwinding control system.Simulation of the fuzzy controller carried out in the MATLAB(Simulink)environment proves that the control system based on fuzzy controller is superior in quality,precision and operation to a conventional optimal PID controller.The outlined experimental results also show the effectiveness and the robustness of the fuzzy PID controller in good dynamic performance,high robustness to parameter variation and disturbance.
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.
文摘The pattern for filament wound toroidal vessels derived from differential geometry is presented. The pattern design and optimization procedure was put forward according to imposed design requirements. The mathematical model and movement equations of winding torns are obtained by analytic geometry. A computer simulation system of filament winding process based on optimal pattern design was developed to verify the correctness and practicability of the winding pattern. The optimum pattern and winding simulation were performed by this system. The simulation results show that the pattern satisfies both winding principles and structural optimization. The recommended design-oriented method can be applied to the preliminary design of filament wound toroidal vessels.
基金supported by the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301400 and 2021ZD0301200)the National Natural Science Foundation of China(Grants No.11874343,92365205,11974334,12404576,and W2411001)+3 种基金the Postdoctoral Innovative Talents Support program(BX20230349)China Postdoctoral Science Foundation Funded Project(2024M763125)Xiaomi Young Talents Program,the Fundamental Research Funds for the Central Universities(Grant No.WK2030000085)the USTC Major Frontier Research Program(Grant No.LS2030000002).
文摘Non-Hermitian(NH)systems have revealed unique topological phenomena that are not observed in Hermitian counterparts,such as novel topology classifications and the NH skin effect.In periodic NH systems,eigenenergies become complex and exhibit windings in the complex plane,while eigenstate winding numbers,which are strictly integers in Hermitian systems,can take half-integer values.However,direct experimental observation of NH winding of both eigenenergies and eigenstates,especially the half-integer winding,remains a significant challenge.In this work,we utilize the orbital angular momentum(OAM)synthetic dimension to construct an NH topological lattice and achieve direct observation of both eigenstate and eigenenergy windings.We report the first experimental observation of a half-integer eigenstate winding number,and reveal the intrinsic relationship between the direction in the NH skin dynamics and eigenenergy windings.Furthermore,by partitioning the OAM chain into two semi-infinite chains,we observe zero boundary modes and demonstrate that their distributions are jointly determined by the winding numbers of both the eigenstates and eigenenergies.This work provides comprehensive insights into NH topologies and offers a new experimental platform for exploring NH phenomena.
基金financially supported by the National Key Research and Development Program of China(No.2018YFB0104200)。
文摘Transition metal phosphides(TMPs)are recognized as such promising supercapacitor materials for the practical application,due to their superior electrical conductivity and excellent redox activity.Here,self-supported three-dimensional NiCoP nanoparticles embedded in NiCoO2 nano wires(NiCoO2/NiCoP)electrode consisting of nickel cobalt phosphides(NiCoP)with high activity and nickel cobalt oxides(NiCoO2)with good stability were fabricated by a hydrothermal and phosphorization method.The electrode integrates the advantages of nanowire arrays for fast ion transport and foam Ni for effective charge transport and flexibility.Benefitting the proper composition control of the nanohybrid and unique structure design,the optimized NiCoO2/NiCoP-20 exhibits a high specific capacitance of 3204 F·g-1 at 1 A·g-1 in 3 mol·L-1 KOH aqueous electrolyte in a three-electrode system.Moreover,the asymmetric supercapacitor assembled with the prepared NiCoO2/NiCoP-20 and activated carbon achieves a specific capacitance of 116 F·g-1 with a high energy density of 40.32 Wh·kg-1 at the power density of 800.18 W·kg-1.The practical application is further demonstrated with all-solid-state winding supercapacitor devices,with decent flexibility,in series to light the Central South University(CSU)logo consisting of 21 red LED indicators.
基金Fundamental Research Funds for the Central Universities (YWF-10-01-B30)
文摘Optical fiber coil winding model is used to guide proper and high precision coil winding for fiber optic gyroscope （FOG） application. Based on the large-deformation theory of elasticity, stress analysis of optical fiber free end has been made and balance equation of infinitesimal fiber is deduced, then deformation equation is derived by substituting terminal conditions. On condition that only axial tensile force exists, approximate curve equation has been built in small angle deformation scope. The comparison of tangent point longitudinal coordinate result between theory and approximation gives constant of integration, and expression with tangent point as origin of coordinate is readjusted. Analyzing the winding parameters of an example, it is clear that the horizontal distance from the highest point of wheel to fiber tangent point has millimeter order of magnitude and significant difference with fiber tension variation, and maintains invariant when wheel radius changes. The height of tension and accurate position of tangent point are defined for proper fiber guide. For application to fiber optic gyroscope, spiral-disc winding method and nonideal deformation of straddle section are analyzed, and then spiral-disc quadrupole pattern winding method has been introduced and realized by winding system. The winding results approve that the winding model is applicable.
