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.

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.

An Improved Stator Flux Observation Method of Permanent Magnet Synchronous Motor

The stator flux and electromagnetic torque observation is the basis of direct torque controlled permanent magnet synchronous motor( PMSM) drive system. However,the traditional stator flux observer based on voltage model is affected by integral initial values and integral drift,that based on current model is affected by the parameters of PMSM,so a new stator flux observation method is proposed based on an improved secondorder generalized integrator( SOGI). Compared to the stator flux observation method based on the conventional SOGI,the proposed method can not only overcome the influence of integral initial values and integral drift,but also completely eliminate the DC offset's influence. Therefore,the observation accuracy of stator flux is further improved. The simulation and experimental results both show that the proposed method has a higher stator flux and electromagnetic torque observation precision.

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 cireulatin8 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 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.

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.

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.

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.

Design strategy for detent force reduction of permanent magnet linear synchronous motor

The detent force of a permanent magnet linear synchronous motor （PMLSM） is analyzed and the corresponding optimization methods are presented to reduce it. The detent force, which is divided into two components, i.e. resulting from the end effect and resulting from the slotting effect, can be analyzed respectively by the finite element method （FEM）. To reduce the detent force arising from the end effect, several optimal design techniques are utilized, namely, adopting the suitable length and end shape of the primary armature. The detent force resulting from the slotting effect is reduced by means of skewing and adjusting the width of the magnets mounted on the secondary armature, and adopting the fractional slots of the primary armature. The validity of the analytical detent force predictions and the effectiveness of the detent force reduction techniques are verified by the experimental measurements.

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.

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.

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.

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.

Analysis of Temperature Rise in High-Speed Permanent Magnet Synchronous Traction Motors by Coupling the Equivalent Thermal Circuit Method and Computational Fluid Dynamics

To solve the problem of temperature rise caused by the high power density of high-speed permanent magnet synchronous traction motors,the temperature rise of various components in the motor is analyzed by coupling the equivalent thermal circuit method and computational fluid dynamics.Also,a cooling strategy is proposed to solve the problem of temperature rise,which is expected to prolong the service life of these devices.First,the theoretical bases of the approaches used to study heat transfer and fluid mechanics are discussed,then the fluid flow for the considered motor is analyzed,and the equivalent thermal circuit method is introduced for the calculation of the temperature rise.Finally,the stator,rotor loss,motor temperature rise,and the proposed cooling method are also explored through experiments.According to the results,the stator temperature at 50,000 r/min and 60,000 r/min at no-load operation is 68℃ and 76℃,respectively.By monitoring the temperature of the air outlets inside and outside the motor at different speeds,it is also found that the motor reaches a stable temperature rise after 65 min of operation.Coupling of the thermal circuit method and computational fluid dynamics is a strategy that can provide the average temperature rise of each component and can also comprehensively calculate the temperature of each local point.We conclude that a hybrid cooling strategy based on axial air cooling of the inner air duct of the motor and water cooling of the stator can meet the design requirements for the ventilation and cooling of this type of motors.

Composite Feedforward Compensation for Force Ripple in Permanent Magnet Linear Synchronous Motors

This paper presents a method for compensating the force ripple in permanent magnet linear synchronous motors(PMLSMs)by adopting a composite feedforward compensation scheme.Firstly,the vector control system of PMLSMs is described,and various force disturbances influencing the electromagnetic thrust are analyzed.As a result,the mathematical model of the whole system considering the force ripple is established.Then,a novel composite feedforward compensation scheme is proposed,which consists of a recursive least squares(RLS)parameter identification component and two feedforward compensation loops corresponding to the reference position trajectory and the force ripple,respectively.Finally,the effectiveness and advantages of the proposed composite feedforward compensation are demonstrated by simulation.The main incentive of this paper is the combination with the composite feedforward compensation loop corresponding to the reference position trajectory to improve the compensation effect of force ripple in PMLSMs.

基于MAGNET的低速永磁直线同步电动机电磁场数值计算与分析

提出了一种新型直线电机,简要介绍了这种电机的基本结构及运行机理,应用Magnet软件对具有不同结构的两种电机的电磁场进行了数值计算。通过计算结果进一步分析和计算得到了低速永磁直线同步电机的二维磁场分布和气隙磁密的变化波形。所做研究为新型低速永磁直线同步电动机提供了一种行之有效的设计方法。

The Characteristics Analysis and Cogging Torque Optimization of a Surface-Interior Permanent Magnet Synchronous Motor

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.

基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断研究

该文提出一种基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断方法。首先,建立电机的d轴等效磁路模型,分析均匀退磁故障后径向气隙磁密的变化规律;然后,获取电机的径向气隙磁密和定子电流信号,对各极下径向气隙磁密幅值进行归一化处理,并绘制雷达图,根据雷达图和比较相同定子电流幅值下健康电机和故障电机的各极下径向气隙磁密幅值的平均值,来诊断均匀退磁故障;利用空载各极下径向气隙磁密幅值的平均值计算故障程度。最后,仿真和实验结果均验证所提均匀退磁故障诊断方法的有效性。

基于比例谐振内模扩张状态观测器的PMLSM推力波动抑制策略

定位力是永磁同步直线电机(PMLSM)产生推力波动的主要原因,导致振动和噪声,恶化驱动系统运行性能。针对这一问题,该文提出一种基于比例谐振内模扩张状态观测器(PR-IMESO)的PMLSM推力波动抑制策略以提高系统控制精度和运行性能。首先,对PMLSM推力波动进行建模与分析,针对推力波动中占比较大的定位力分量,根据内模原理研究考虑定位力模型的内模扩张状态观测器(IMESO),并在观测器中引入谐振项以加强对二次脉动定位力的抑制。所提出抑制策略对PMLSM定位力具有良好的观测及补偿能力,还可对其余未建模的复杂动子推力波动进行抑制,具有较好的推力波动整体抑制效果。最后,在一台750 W的PMLSM实验平台上验证所提出抑制策略的有效性。