Integrated Sliding Mode Velocity Control of Linear Permanent Magnet Synchronous Motor with Thrust Ripple Compensation

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.

Optimization Design and Analysis of a Hybrid Permanent Magnet Flux-Switching Motor with Compound Rotor Configuration

This paper proposes a type of flux-switching permanent magnet(FSPM)motor,where the design concept of the hybrid permanent magnets(HPM)and the compound rotor are incorporated into the motor design.In such design,the proposed motor can not only realize the significant reduction of NdFeB volume,but also artfully convert external magnetic flux leakage into the air-gap field to achieve competitive torque density and desirable PM usage efficiency.For extensive investigation,two topologies of the HPM are designed and analyzed for the proposed motor,which consist of the parallel-magnetic-hybrid(PMH)mode and serial-magnetic-hybrid(SMH)mode.To fully exploit the potential advantages of the proposed motor,a multi-objective optimization design is conducted,where the response surface method(RSM)and sequential non-linear programming(SNP)method are purposely utilized.After optimization,the electromagnetic performances of the motor with PMH mode and SMH mode are evaluated and compared by using finite element method(FEM),which include the back-EMF,cogging torque,output torque,and so on.Furthermore,the partial demagnetization of the ferrite PM is also investigated in the paper.Finally,the theoretical analysis and simulation study verify the effectiveness of the proposed motor and corresponding optimization design.

Adaptive PI Control Strategy for Flat Permanent Magnet Linear Synchronous Motor Vibration Suppression

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.

Comparative Analysis of Bilateral Permanent Magnet Linear Synchronous Motors With Different Structures

Permanent magnet linear synchronous motor(PMLSM)has the advantages of high thrust density and good control accuracy,which can be applied in high-power and high-speed occasions.In this paper,the analytical models are established to obtain the electromagnetic performance for the PMLSMs with dual secondaries and dual primaries.The air-gap flux density and the electromagnetic thrust are also obtained by the finite element model to verify theoretical analysis.Besides,an improved structure is also put forward in order to suppress the thrust fluctuation of the PMLSM.Finally,the advantages and disadvantages of two PMLSMs topologies are listed.These analyses would provide a guide for the design of PMLSMs applied in high-power and high-speed occasions.

Magnetic field and performance analysis of a tubular permanent magnet linear synchronous motor applied in elevator door system

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.

Study on three dimensional electromagnetic model for permanent magnet linear synchronous motor

In this paper, with the non-salient pole permanent magnet linear synchronous motor (PMLSM)being cited, by using Fourier transform method and "slot-by-slot", "pole -by-pole" current approach, a 3D electromagnetic field model of PMLSM is established. Special attention is paid to its structure and the influence of longitudinal and transverse end effect. The distribution of electromagnetic field of PMLSM can be obtained directly and promptly by using FFT algorithm. It can also be used for the analysis of other LSM.

Optimal design of auxiliary-teeth to solve circulation current reduction of permanent magnet linear synchronous motor

A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM).Due to the unbalanced back electro-motive force (EMF) and impedance produced,unbalanced current is generated.The circulating current,which is caused by a decrease in the thrust,is generated by the unbalanced current.The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE),and compared with the basic model through finite element analysis (FEA).As a result,the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase.Also,this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.

Study on a New High Frequency Moving Coil Permanent Magnet Linear Motor

In order to improve the characteristics of a conventional moving coil permanent magnet linear motor （MCPMLM）, such as weak points on export force, response time, response speed, we studied a permanent magnet （PM） structure that is a key component of MCPMLM. Different magnetization techniques of single PM and differ- ent array structures of multiple PMs are compared, and a new MCPMLM magnetized along the external field force lines wing eight pieces of a tegular Halbach magnet array with air gaps is proposed as well. The analysis on magnetic field and experimental results of MCPMLM demonstrates that the force between the coil and the PM increases by more than 40%. The simulation frequeney is close to 350 Hz at -3 dB , and the response time is O. 005 s. In addition, the experiment frequency reaches 300 Hz at -3 dB and the response time is 0. 004 s, which agrees well with the simulation results. It means that the developed MCPMLM enjoys advantages in high frequency and rapid response, and can satisfy the requirements of a high speed electro-hydraulic proportional valve.

A Permanent Magnet Linear Synchronous Motor Drive for HTS Maglev Transportation Systems

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.

Characteristics of permanent magnet linear synchronous motor fed by spwm inverter based on field-circuit coupled method

Presented field-circuit coupled adaptive time-stepping finite element method to study on permanent magnet linear synchronous motor (PMLSM) characteristics fed by SPWM voltage source inverter.In air-gap field where the direction or magnitude of the field is changing rapidly,the smallest elements are demanded due to high accuracy to use adaptive meshing technique.The co-simulation was used with the status space functions and time-step finite element functions,in which time-step of the status space functions was the smallest than finite element functions'.The magnitude relation of the normal elec- tromagnetic force and tangential electromagnetic force and the period were attained,and current curve was very abrupt at current zero area due to the bigger resistance and leak- age reactance,including main characteristics of motor voltage and velocity.The simulation results compare triumphantly with the experiments results.

Temperature Rise Calculation and Velocity Planning of Permanent Magnet Linear Synchronous Motor under Trapezoidal Speed

For permanent magnet linear synchronous motor(PMLSM) working at trapezoidal speed for long time, high thrust brings high temperature rise, while low thrust limits dynamic performance. Thus, it is crucial to find a balance between temperature rise and dynamic performance. In this paper, a velocity planning model of the PMLSM at trapezoidal speed based on electromagnetic-fluid-thermal(EFT) field is proposed to obtain the optimal dynamic performance under temperature limitation. In this model, the winding loss is calculated considering the acceleration and deceleration time. The loss model is indirectly verified by the temperature rise experiment of an annular winding sample. The actual working conditions of the PMLSM are simulated by dynamic grid technology to research the influence of acceleration and deceleration on fluid flow in the air gap, and the variation rule of the thermal boundary condition is analyzed. Combined with the above conditions, the temperature rise of a coreless PMLSM(CPMLSM) under the rated working condition is calculated and analyzed in detail. Through this method and several iterations, the optimal dynamic performance under the temperature limitation is achieved. The result is verified by a comparison between simulation and prototype tests, which can help improve the dynamic performance.

Calculation of optimal current density of double side permanent magnet linear synchronous motor

The use of design method considering a coil temperature to maximize the thrust density of a double side coreless permanent magnet linear synchronous motor(PMLSM) was presented.The optimal current density where the coil temperature reaches an allowable temperature with heat analysis was applied to a magnetic circuit design.Changing optimal current density is verified whenever the design parameters of the motor are altered.The design parameters of the motor were applied to thrust calculation.In this way,the optimal model,which is a reversal of the existing design method,is deduced.The results were compared with the experimental data to verify their validity.When the convection heat transfer coefficient is applied to other models,the results of the analysis and test values show good concordance.The method proposed has some limitations.

SIMULATION RESEARCH ON CHARACTERISTICS OFPERMANENT MAGNET LINEAR SYNCHRONOUS MOTOR

In this paper, a simulation model of Permanent Magnet Linear Synchronous Motor (PMLSM) is established by using phase equations method. Special attention is paid to its structure and the influence of longitudinal end effect and the unbalance of current. The analytic method can be used for the analysis of dynamic and static characteristics of PMLSM.

Impulsive control for permanent magnet synchronous motors with uncertainties:LMI approach

A permanent magnet synchronous motor （PMSM） may have chaotic behaviours under certain working conditions, especially for uncertain values of parameters, which threatens the security and stability of motor-driven operation. Hence, it is important to study methods of controlling or suppressing chaos in PMSMs. In this paper, the stability of a PMSM with parameter uncertainties is investigated. After uncertain matrices which represent the variable system parameters are formulated through matrix analysis, a novel asymptotical stability criterion is established by employing the method of Lyapunov functions and linear matrix inequality technology. An example is also given to illustrate the effectiveness of our results.

Design of a Transverse-flux Permanent-magnet Linear Generator and Controller for Use with a Free-piston Stirling Engine

Transverse-flux with high efficiency has been applied in Stirling engine and permanent magnet synchronous linear generator system,however it is restricted for large application because of low and complex process.A novel type of cylindrical,non-overlapping,transverse-flux,and permanent-magnet linear motor（TFPLM） is investigated,furthermore,a high power factor and less process complexity structure research is developed.The impact of magnetic leakage factor on power factor is discussed,by using the Finite Element Analysis（FEA） model of stirling engine and TFPLM,an optimization method for electro-magnetic design of TFPLM is proposed based on magnetic leakage factor.The relation between power factor and structure parameter is investigated,and a structure parameter optimization method is proposed taking power factor maximum as a goal.At last,the test bench is founded,starting experimental and generating experimental are performed,and a good agreement of simulation and experimental is achieved.The power factor is improved and the process complexity is decreased.This research provides the instruction to design high-power factor permanent-magnet linear generator.

Robust fuzzy sliding-mode control for T-S model based permanent magnet synchronous motor

A fuzzy sliding-mode control (FSMC) scheme based on T-S fuzzy models was proposed for the permanent magnet synchronous motor (PMSM) drive system to solve the speed tracking problem. A T-S fuzzy model was firstly formed to represent the nonlinear system of PMSM. For converting the tracking control into a stabilization problem, a new control design was proposed to define the internal desired states. Then, the FSMC controller for PMSM system with parameter variation and load disturbance was designed based on the fuzzy model. The performance of the proposed controller was verified by experimental results on PMSM system. The results show that the FSMC scheme can drive the dynamics of PMSM into a designated sliding surface in finite time and guarantee the property of asymptotical stability. The information of upper bound of modeling errors as well as perturbations is not required when using the FSMC controller.

AN ANALYSIS OF AXISYMMETRIC MAGNETIC FIELD OF LINEAR OSCILLATION MOTOR

In this paper, using axial field finite analysis method, the field of a movable core type linear oscillation motor is analyzed. The program of axial field finite analysis is worked out. Using this program, we analyze various fields, including the field excited by permanent magnet materials, the field by two coils respectively, and the fields with the core moving to various positions.

梯形Halbach交替极无铁心永磁同步直线电机特性分析与优化设计

针对无铁心永磁同步直线电机(PMLSM)存在推力波动问题以及磁极结构对永磁体利用率的影响,从结构方面着手,提出一种梯形Halbach交替极磁极结构的无铁心永磁同步直线电机,对Halbach阵列进行优化设计。首先通过有限元法对比在Halbach交替极、双层Halbach磁极与梯形Halbach交替极3种磁极结构中PMLSM的电磁性能,分别对气隙磁场谐波成分、空载反电动势、电磁推力以及推力体积比进行计算与对比。其次,采用等效磁化强度法定性分析磁极结构对电机出力性能的影响,并引入Kriging模型,结合多目标优化算法对关键参数进行优化以提高电机平均推力和推力体积比,降低推力波动,得到3个优化目标的Pareto前沿。最后,通过仿真分析验证设计方法的有效性以及电机性能的改善。结果表明:梯形Halbach交替极磁极结构永磁体利用率更高,具有实用价值;梯形Halbach交替极PMLSM能够有效抑制推力波动并保持在7%左右,适用于高精确度加工设备。

横向磁通永磁直线电机电磁振动特性分析

横向磁通永磁直线电机的电负荷与磁负荷相互解耦,且各相之间相互解耦,易于实现模块化和多相化,因此在石油开采领域有着良好的应用前景。首先,该文基于磁场调制原理,对横向磁通永磁直线电机的径向电磁力波进行了推导计算,得出对径向电磁力波影响最大的因素为轴向气隙磁通密度分量与径向气隙磁通密度分量,在此基础上对径向电磁力波的时空特性与频谱特性进行仿真计算,得出电枢磁通密度对电机径向电磁力波的频谱特性的影响;然后,考虑到电机实际运行中可能出现的次级偏心问题,揭示偏心度的大小对径向电磁力波幅值的影响,并对比不同偏心度下的电机径向磁拉力与轴向磁拉力,定量分析偏心度对不平衡磁拉力的影响;最后,为避免共振,利用有限元软件对电机的初级进行了模态分析与谐响应分析,结果表明低速状态下横向磁通永磁直线电机的额定运行频率较低,不会引起初级的共振,适合用作往复式潜油电泵的驱动电机。

基于sigmoid滤波器的永磁轮毂电机自抗扰控制

相比燃油拖拉机,电动拖拉机具有节能高效、绿色清洁的优点。分布式驱动电动拖拉机结构简单、控制维度多,能进一步提高电动拖拉机的工作效率和作业精度。但是电机检测转速噪声导致轮毂电机速度波动严重,复杂路面及多种作业工况下进一步加剧了上述问题,严重降低了拖拉机的作业质量。针对上述问题,该研究提出一种基于sigmoid滤波器的线性自抗扰控制(linear active disturbance rejection control,LADRC)以提高轮毂电机的转速稳定性和抗扰动能力。该控制策略在传统LADRC的基础上引入sigmoid滤波器至扩张状态观测器(extended state observer,ESO),根据输入噪声信号误差变化改变滤波器带宽,以抑制观测误差中的中高频干扰信号,同时避免滤波器积分环节对轮毂电机速度跟踪快速性的影响,具有较快的收敛性。搭建试验平台对所提出控制策略进行试验验证,结果表明:与传统LADRC策略相比,本文所提控制策略在变速和变载工况下的转速脉动分别减小了32%和41.67%,iq电流脉动分别减小了6.25%和4.17%,可在快速、准确跟踪给定转速的同时,大幅提高轮毂电机驱动系统的噪声抑制性能,为复杂环境下电动拖拉机高精度作业提供技术参考。