For a new type of toroidal permanent magnet linear motor(TPMLSM), this paper analyzes the thrust fluctuation in the constant acceleration operation of the motor from the Angle of the cogging force of the linear motor....For a new type of toroidal permanent magnet linear motor(TPMLSM), this paper analyzes the thrust fluctuation in the constant acceleration operation of the motor from the Angle of the cogging force of the linear motor. For the motor whose structure has been determined and processed, the structural parameters of the motor cannot be changed, and its performance cannot be improved from the perspective of the motor body.Therefore, this paper tries to consider the influence of the cogging force on the normal operation of the motor from the perspective of control. In this paper, starting from the body structure of motor, first on the annular linear motor of the cogging force characteristics were extracted, and its expression is obtained by Fourier decomposition, then investigated considering the cogging force and does not consider the cogging force control of motor model, it can be seen that the control performance deteriorates significantly after considering cogging force of the motor, and the acceleration fluctuation increases significantly during the operation of the motor. On this basis, disturbance observation algorithm is introduced, and feedforward compensation is carried out by extracting the characteristic values of the disturbance model. The results show that the disturbance observer can suppress the thrust fluctuation caused by the motor cogging force to a large extent, and it can reduce the peak-to-peak value of the thrust fluctuation by more than 85% during the motor acceleration operation.展开更多
Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of ...Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of high-performance PMSM for electric vehicles.A fast and accurate magnetic field calculation model for interior permanent magnet synchronous machine(IPMSM)is proposed in this article.Based on the traditional magnetic potential permeance method,the stator cogging effect and complex boundary conditions of the IPMSM can be fully considered in this model,so as to realize the rapid calculation of equivalent magnetomotive force(MMF),air gap permeance,and other key electromagnetic properties.In this article,a 6-pole 36-slot IPMSM is taken as an example to establish its equivalent solution model,thereby the cogging torque is accurately calculated.And the validity of this model is verified by a variety of different magnetic pole structures,pole slot combinations machines,and prototype experiments.In addition,the improvement measure of the machine with different combination of pole arc coefficient is also studied based on this model.Cogging torque and electromagnetic vibration can be effectively weakened.Combined with the finite element model and multi-physics coupling model,the electromagnetic characteristics and vibration performance of this machine are comprehensively compared and analyzed.The analysis results have well verified its effectiveness.It can be extended to other structures or types of PMSM and has very important practical value and research significance.展开更多
With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increas...With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increased.To solve the problem of oversized cogging torque of axial flux PMSM,a rotor topology with hybrid permanent magnet is proposed to weaken the cogging torque.Firstly,the expression of the cogging torque of the axial flux motor is derived,and the influence of the pole-arc ratio of the permanent magnet on the cogging torque is analyzed.Secondly,the rotor structure with hybrid permanent magnet is adopted to reduce the cogging torque.According to the analytical analysis,the constraints of the size and pole-arc ratio between the hybrid permanent magnets are obtained,and the two permanent magnets related to the minimum cogging torque are determined.And the analysis results are verified by the finite element simulation.Furthermore,the motor performance with and without the hybrid permanent magnet is compared with each other.Finally,the cogging torque is significantly reduced by adopting a rotor structure with hybrid permanent magnets.展开更多
The investigation involves detailed qualitative analysis and quantitative calculation of cogging torque in PM torque motors. The object of this analysis includes symmetric and non-symmetric motors, and the cause of th...The investigation involves detailed qualitative analysis and quantitative calculation of cogging torque in PM torque motors. The object of this analysis includes symmetric and non-symmetric motors, and the cause of the presence of Zth and 2Pth cogging torque is revealed.Then the optimum number of teeth per pole for both quasisquare and sinusoidal magnetic fields are presented. Finally, the experimental results are given.展开更多
Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging f...Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at dif- ferent position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods, namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.展开更多
In order to reduce the cogging torque, this paper investigates the influence of some parameters on the cogging torque developed by directly driven permanent magnet synchronous wind generators. Based on the remanent ma...In order to reduce the cogging torque, this paper investigates the influence of some parameters on the cogging torque developed by directly driven permanent magnet synchronous wind generators. Based on the remanent magnetic flux densities, the cogging torque is computed by using finite element method. It is shown that many parameters have influence on cogging torque and the slot and pole number combination has a significant effect on cogging torque. A simple factor has been introduced to indicate the effect of the slot and pole number combination. Some practical experience to reduce the cogging torque was applied to 2 MW three phase permanent magnet synchronous generator at rated speed of 37.5 rpm for wind energy conversion. The simulation and experiment results verify the effect of the proposed method.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
The influence of bread-loaf shaped magnet poles under parallel magnetization on the cogging torque of surface-mounted permanent magnet(SPM)motors is studied.For the SPM motors having magnetic poles with eccentricity a...The influence of bread-loaf shaped magnet poles under parallel magnetization on the cogging torque of surface-mounted permanent magnet(SPM)motors is studied.For the SPM motors having magnetic poles with eccentricity and sine harmonic compensation,the electromagnetic performances of integer and fractional slot motors are compared.It is found that the cogging torque and torque ripple of the integer and fractional slot motors can be reduced with the same eccentric magnet pole.The cogging torque and torque ripple of a fractional slot motor can be decreased by sine harmonic compensation,however,the same sine harmonic compensation has a small influence in integer slot motors.By varying the magnetic poles,the contribution of the field harmonics(k=(2n+1)p),which are a direct result of magnet magnetization,to the cogging torque also changes.The electromagnetic performance of a 3 kW prototype is tested,and it is found that the experimental results validate the theoretical investigation.展开更多
This paper proposes optimal stator skewed slot analytical method for cogging torque reduction in surface-interior permanent magnet synchronous motor(SIPMSM)and analyzes the characteristics of SIPMSM.The series-paralle...This paper proposes optimal stator skewed slot analytical method for cogging torque reduction in surface-interior permanent magnet synchronous motor(SIPMSM)and analyzes the characteristics of SIPMSM.The series-parallel equivalent magnetic circuit models(EMCMs)of SIPMSM is built based on the characteristics of magnetic circuits,which is used to design the basic electromagnetic parameters of SIPMSM.Analytical expressions of cogging torque are derived from applying analytical techniques.Stator skewed slot for cogging torque minimum is adopted,and the stator skewed slot pitch is confirmed based on the analytical expressions of the resultant cogging torque.The cogging torque,torque ripple,back electromotive force(back-EMF),power-angle characteristics,efficiency and power factor of SIPMSM are analyzed by establishing 3-dimensional finite element model(3-D-FED)of SIPMSM with stator skewed slot and straight slot.It is shown that the comprehensive performance of optimized SIPMSM is improved as confirmed by finite element analysis and analytical calculation results.展开更多
Axial flux permanent magnet synchronous motors(AFPMSMs)have been widely used in wind-power generation,electric vehicles,aircraft,and other renewable-energy applications owing to their high power density,operating effi...Axial flux permanent magnet synchronous motors(AFPMSMs)have been widely used in wind-power generation,electric vehicles,aircraft,and other renewable-energy applications owing to their high power density,operating efficiency,and integrability.To facilitate comprehensive research on AFPMSM,this article reviews the developments in the research on the design and control optimization of AFPMSMs.First,the basic topologies of AFPMSMs are introduced and classified.Second,the key points of the design optimization of core and coreless AFPMSMs are summarized from the aspects of parameter design,structure design,and material optimization.Third,because efficiency improvement is an issue that needs to be addressed when AFPMSMs are applied to electric or other vehicles,the development status of efficiency-optimization control strategies is reviewed.Moreover,control strategies proposed to suppress torque ripple caused by the small inductance of disc coreless permanent magnet synchronous motors(DCPMSMs)are summarized.An overview of the rotor-synchronization control strategies for disc contra-rotating permanent magnet synchronous motors(CRPMSMs)is presented.Finally,the current difficulties and development trends revealed in this review are discussed.展开更多
Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosys...Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosystems.This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output torque.Firstly,the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed.Secondly,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM.Then,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in CTR.Meanwhile,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation.Finally,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.展开更多
为满足越来越多的脑卒中患者辅助行走和康复训练的需要,设计了一款下肢外骨骼机器人模型,采用D-H参数法建立踝关节、膝关节、髋关节坐标系,推演出步态周期内的坐标方程。为了安全起见,要求脑卒中患者步行速度慢且步长短,利用CoG(Center ...为满足越来越多的脑卒中患者辅助行走和康复训练的需要,设计了一款下肢外骨骼机器人模型,采用D-H参数法建立踝关节、膝关节、髋关节坐标系,推演出步态周期内的坐标方程。为了安全起见,要求脑卒中患者步行速度慢且步长短,利用CoG(Center of Gravity,重心地面投影点)作为步态规划中的稳定性判断依据,并用Robotics Toolbox for Matlab仿真,结果表明:下肢外骨骼康复机器人在康复训练过程中各关节具有连续且稳定的步态轨迹,为后续脑卒中患者使用的下肢外骨骼康复机器人样机研制提供了必要的理论依据。展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 51507813。
文摘For a new type of toroidal permanent magnet linear motor(TPMLSM), this paper analyzes the thrust fluctuation in the constant acceleration operation of the motor from the Angle of the cogging force of the linear motor. For the motor whose structure has been determined and processed, the structural parameters of the motor cannot be changed, and its performance cannot be improved from the perspective of the motor body.Therefore, this paper tries to consider the influence of the cogging force on the normal operation of the motor from the perspective of control. In this paper, starting from the body structure of motor, first on the annular linear motor of the cogging force characteristics were extracted, and its expression is obtained by Fourier decomposition, then investigated considering the cogging force and does not consider the cogging force control of motor model, it can be seen that the control performance deteriorates significantly after considering cogging force of the motor, and the acceleration fluctuation increases significantly during the operation of the motor. On this basis, disturbance observation algorithm is introduced, and feedforward compensation is carried out by extracting the characteristic values of the disturbance model. The results show that the disturbance observer can suppress the thrust fluctuation caused by the motor cogging force to a large extent, and it can reduce the peak-to-peak value of the thrust fluctuation by more than 85% during the motor acceleration operation.
基金supported in part by the National Natural Science Foundation of China under Grant 51737008.
文摘Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of high-performance PMSM for electric vehicles.A fast and accurate magnetic field calculation model for interior permanent magnet synchronous machine(IPMSM)is proposed in this article.Based on the traditional magnetic potential permeance method,the stator cogging effect and complex boundary conditions of the IPMSM can be fully considered in this model,so as to realize the rapid calculation of equivalent magnetomotive force(MMF),air gap permeance,and other key electromagnetic properties.In this article,a 6-pole 36-slot IPMSM is taken as an example to establish its equivalent solution model,thereby the cogging torque is accurately calculated.And the validity of this model is verified by a variety of different magnetic pole structures,pole slot combinations machines,and prototype experiments.In addition,the improvement measure of the machine with different combination of pole arc coefficient is also studied based on this model.Cogging torque and electromagnetic vibration can be effectively weakened.Combined with the finite element model and multi-physics coupling model,the electromagnetic characteristics and vibration performance of this machine are comprehensively compared and analyzed.The analysis results have well verified its effectiveness.It can be extended to other structures or types of PMSM and has very important practical value and research significance.
基金supported by the Natural Science Foundation of Hubei Province(No.2019 CFB759)。
文摘With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increased.To solve the problem of oversized cogging torque of axial flux PMSM,a rotor topology with hybrid permanent magnet is proposed to weaken the cogging torque.Firstly,the expression of the cogging torque of the axial flux motor is derived,and the influence of the pole-arc ratio of the permanent magnet on the cogging torque is analyzed.Secondly,the rotor structure with hybrid permanent magnet is adopted to reduce the cogging torque.According to the analytical analysis,the constraints of the size and pole-arc ratio between the hybrid permanent magnets are obtained,and the two permanent magnets related to the minimum cogging torque are determined.And the analysis results are verified by the finite element simulation.Furthermore,the motor performance with and without the hybrid permanent magnet is compared with each other.Finally,the cogging torque is significantly reduced by adopting a rotor structure with hybrid permanent magnets.
文摘The investigation involves detailed qualitative analysis and quantitative calculation of cogging torque in PM torque motors. The object of this analysis includes symmetric and non-symmetric motors, and the cause of the presence of Zth and 2Pth cogging torque is revealed.Then the optimum number of teeth per pole for both quasisquare and sinusoidal magnetic fields are presented. Finally, the experimental results are given.
基金Supported by the National Natural Science Foundation of China (60474043)
文摘Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at dif- ferent position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods, namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.
文摘In order to reduce the cogging torque, this paper investigates the influence of some parameters on the cogging torque developed by directly driven permanent magnet synchronous wind generators. Based on the remanent magnetic flux densities, the cogging torque is computed by using finite element method. It is shown that many parameters have influence on cogging torque and the slot and pole number combination has a significant effect on cogging torque. A simple factor has been introduced to indicate the effect of the slot and pole number combination. Some practical experience to reduce the cogging torque was applied to 2 MW three phase permanent magnet synchronous generator at rated speed of 37.5 rpm for wind energy conversion. The simulation and experiment results verify the effect of the proposed method.
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 by the Key Research and Development Program of Jiangsu Province(BE2018107).
文摘The influence of bread-loaf shaped magnet poles under parallel magnetization on the cogging torque of surface-mounted permanent magnet(SPM)motors is studied.For the SPM motors having magnetic poles with eccentricity and sine harmonic compensation,the electromagnetic performances of integer and fractional slot motors are compared.It is found that the cogging torque and torque ripple of the integer and fractional slot motors can be reduced with the same eccentric magnet pole.The cogging torque and torque ripple of a fractional slot motor can be decreased by sine harmonic compensation,however,the same sine harmonic compensation has a small influence in integer slot motors.By varying the magnetic poles,the contribution of the field harmonics(k=(2n+1)p),which are a direct result of magnet magnetization,to the cogging torque also changes.The electromagnetic performance of a 3 kW prototype is tested,and it is found that the experimental results validate the theoretical investigation.
基金Supported by National Natural Science Foundation of China(U1361109,51777060)Natural Science Foundation of Henan province(162300410117)the he innovative research team plan of Henan Polytechnic University(T2015-2).
文摘This paper proposes optimal stator skewed slot analytical method for cogging torque reduction in surface-interior permanent magnet synchronous motor(SIPMSM)and analyzes the characteristics of SIPMSM.The series-parallel equivalent magnetic circuit models(EMCMs)of SIPMSM is built based on the characteristics of magnetic circuits,which is used to design the basic electromagnetic parameters of SIPMSM.Analytical expressions of cogging torque are derived from applying analytical techniques.Stator skewed slot for cogging torque minimum is adopted,and the stator skewed slot pitch is confirmed based on the analytical expressions of the resultant cogging torque.The cogging torque,torque ripple,back electromotive force(back-EMF),power-angle characteristics,efficiency and power factor of SIPMSM are analyzed by establishing 3-dimensional finite element model(3-D-FED)of SIPMSM with stator skewed slot and straight slot.It is shown that the comprehensive performance of optimized SIPMSM is improved as confirmed by finite element analysis and analytical calculation results.
基金Supported by Shanghai Municipal Natural Science Foundation of China (Grant No.19ZR1418600)。
文摘Axial flux permanent magnet synchronous motors(AFPMSMs)have been widely used in wind-power generation,electric vehicles,aircraft,and other renewable-energy applications owing to their high power density,operating efficiency,and integrability.To facilitate comprehensive research on AFPMSM,this article reviews the developments in the research on the design and control optimization of AFPMSMs.First,the basic topologies of AFPMSMs are introduced and classified.Second,the key points of the design optimization of core and coreless AFPMSMs are summarized from the aspects of parameter design,structure design,and material optimization.Third,because efficiency improvement is an issue that needs to be addressed when AFPMSMs are applied to electric or other vehicles,the development status of efficiency-optimization control strategies is reviewed.Moreover,control strategies proposed to suppress torque ripple caused by the small inductance of disc coreless permanent magnet synchronous motors(DCPMSMs)are summarized.An overview of the rotor-synchronization control strategies for disc contra-rotating permanent magnet synchronous motors(CRPMSMs)is presented.Finally,the current difficulties and development trends revealed in this review are discussed.
基金supported in part by the National Nature Science Foundation of China(NSFC)under Project 52122705。
文摘Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosystems.This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output torque.Firstly,the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed.Secondly,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM.Then,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in CTR.Meanwhile,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation.Finally,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.
文摘为满足越来越多的脑卒中患者辅助行走和康复训练的需要,设计了一款下肢外骨骼机器人模型,采用D-H参数法建立踝关节、膝关节、髋关节坐标系,推演出步态周期内的坐标方程。为了安全起见,要求脑卒中患者步行速度慢且步长短,利用CoG(Center of Gravity,重心地面投影点)作为步态规划中的稳定性判断依据,并用Robotics Toolbox for Matlab仿真,结果表明:下肢外骨骼康复机器人在康复训练过程中各关节具有连续且稳定的步态轨迹,为后续脑卒中患者使用的下肢外骨骼康复机器人样机研制提供了必要的理论依据。
