Use of compensating magnets to reduce thrust imbalance in cylindrical linear pulse motors

A linear pulse motor (LPM) has many advantages for a high-accuracy positioning actuator because it has linear motion without any mechanical link. The flat-type LPM generally is used in many industrial applications. However, it has a disadvantage in that the mover support mechanism becomes complex and heavy because the attraction force between the stator and the mover is very large. As the attraction force is balanced in the cylindrical structure, the cylindrical LPM is allowed to have a simple and lightweight support mechanism. The inset magnet-type cylindrical LPM, which has a permanent magnet between the A-phase and B-phase stator, has such merits as a magnet of simple shape and a reduction of the motor diameter. Its weak point is that thrust unbalance occurs because the magnetic flux pass of the outer poles is longer than that of the inner poles. The thrust unbalance decreases the pull-in thrust force and increases the positioning error. This paper proposes two practical methods to improve the thrust unbalance: 1) the exciting current adjustment; and 2) the method with compensation permanent magnet. These effects are examined with theoretical and experimental results.     

A Direct Drive θ‐Z Motor for Rotary and Linear Motion

A multidimensional positioning mechanism, along with high speed and high accuracy, is essential for an industrial machine. A positioning machine operates precisely in both vertical linear motion (z‐axis) and rotary motion (θ‐axis). A ball screw mechanism is used for the z‐axis whereas a servo motor is used for the θ‐axis. We developed a direct drive θ‐z motor for rotary and linear motion. Torque and thrust are generated directly by the mover. Thus, high speed and high accuracy as well as miniaturization are achieved without using machine elements such as a ball screw and belt. In this paper, we describe the structure and operating principle of the θ‐Z motor, and the sensor that can detect the θ‐axis and the z‐axis position. In addition, we consider a design method that minimizes copper loss by taking advantage of the shape of the permanent magnet and coil. Furthermore, using a prototype we evaluated the characteristics of torque, thrust, and repeatability.     

Static thrust analysis of a cylindrical moving-core linear oscillatory actuator

This paper considers materials for the movers, the volume ratio of the stator and of the mover, and the structure of the mover in a cylindrical moving iron-type linear oscillatory actuator (LOA) having a permanent magnet. As a result, we obtain the following:

• (1) the static thrust characteristics are evaluated on two movers: movers P and S are made of a permendur and a stainless steel, respectively. It is clarified that the static thrust of the mover P is 30 percent larger than that of the mover S;
• (2) it is suggested that the structure of the mover P should be improved to eliminate a “lump” in the static thrust-displacement curve due to the step on the mover, and which disturbs the smooth motion of the LOA.

     

高压断路器新型电机操动机构的研究

本文研究了高压断路器新型电机操动机构,分析了两种不同运动方式的电机操动机构及其运动特性.基于40.5kV户内真空断路器采用电机操动机构,研究了永磁直线直流电机和有限转角永磁无刷直流电机,利用有限元方法对两种电机的基本特性和起动过程进行了动态特性仿真,得到了电机运行时的电磁推力、电流、速度等曲线并进行了分析,分析两种电机操动机构在起动性能、运行方式及机构的复杂性、控制方面等特点,这为高压断路器采用电机操动机构提供了可靠的依据.     

永磁开关磁通直线电动机优化设计

采用基于有限元法的单参数优化方法分析了6/5和6/7动/定子极永磁开关磁通直线电动机的主要设计参数对推力的影响,最大化了其在固定铜耗下的推力。比较两种电机的优化结果,发现其参数优化值和最大推力基本相同,但6/5动/定子极电机的定子结构更为简单。随后采用基于遗传算法的全局优化对6/5动/定子极电机的单参数优化进行了验证。最后,通过对电机端部尺寸的优化,将6/5动/定子极电机齿槽力降低了40%。     

磁链反向式定子永磁无刷直线电机的分析及其驱动系统设计

针对磁链反向式定子永磁无刷直线电机,首先简要介绍了其基本结构,然后从定子绕组磁链人手详细地讨论了该类型电机的运行原理以及各种变量的波形,并利用机电能量转换的基本原理分析了其电磁力的产生机理.在此基础上,对这种磁链反向式定子永磁的直线电机的动态数学模型进行了分析与探讨.最后给出了这种类型电机的样机并设计了相应的驱动器系统以及相应的实验波形和实验结果.     

平面电机的海尔贝克型直线电机执行器

平面电机的电磁执行器由4组海尔贝克(Halbach)型永磁同步直线电机构成。介绍平面电机的结构和工作原理,给出执行器样机的结构方案和解耦电磁力方程,推导执行器样机的运动控制方程,并提出执行器的电流控制策略,给出电流控制、静态力测量、开环定位、闭环定位的实验步骤和结果,其中,500 mA电流阶跃响应的调节时间为2.5 ms,稳态误差小于5 mA;海尔贝克型执行器的机电常数实测值为17.4 N/A,为径向阵列型执行器的1.36倍;开环定位的平均误差为50 mm;闭环10 mm阶跃响应的调节时间为350 ms,稳态误差小于20 mm。实验结果表明,海尔贝克型执行器的电磁力模型较准确,电流控制策略可行。     

改进的永磁同步直线电机直接推力控制策略

针对传统直接推力控制策略的瞬态响应慢和稳态误差大的问题,提出基于线性二次调节器的永磁同步直线电机直接推力控制策略,建立新型的多输入输出的空间状态电机模型,以定子磁链和推力作为状态量,设计线性二次调节器来获得线性状态反馈控制律,并用来取代传统的定子磁链、推力PI调节模块.通过增广的电机空间状态模型达到减小稳态误差和推力波动的目的.通过MATLAB/Simulink仿真,其结果表明,改进的控制策略可以得到更快的动态响应,同时具有减少推力、磁链脉动的效果,所设计的控制系统达到更好的稳态特性和动态特性,具有良好的控制性能.     

Analysis of moving magnet linear dc motor with two straight stators

The thrust force of moving magnet-type linear direct current motors (MM-LDM) is analyzed in this study. A moving magnet-type MM-LDM consists of a stator and a carriage. The stator is composed of two stick shaped electromagnetics and the carriage consists of a movable permanent magnet that is located between the two electromagnets. One of the methods for calculating the thrust force of an MM-LDM is to analyze the energy gradient which is determined by the distribution of magnetic flux. However, this method is very difficult when used to calculate the thrust force of this kind of LDM. This type of MM-LDM can be considered to be a transformer in which the magnet of the mover is assumed to be a one-turn coil carrying a large current. The stored energy in the MM-LDM can be obtained by measuring the self-inductance and the mutual-inductance of the equivalent circuit of the MM-LDM. And this energy gradient gives the thrust force. The calculation of the thrust force induced in this motor shows that the mutual inductance has a large influence on the generation of thrust force.     

六相双定子螺旋运动永磁执行器数学模型研究

针对新型机器人多自由度运动机构的需求,提出了一种新型六相双定子螺旋运动永磁执行器。执行器特点在于每个定子均为六相双Y移30°绕组,两个定子铁心采用螺旋形齿槽结构,对两个定子绕组通入六相不同相序电流组合便可产生多自由度运动方式。执行器具有控制方式灵活、容错性能强、可靠性稳定等优点。首先对螺旋运动永磁执行器的结构及运行机理进行分析,推导了执行器的磁链方程、电压方程、转矩和推力方程。最后构建了瞬态三维多自由度数值分析模型,得到了磁链、电压、转矩和推力的波形,验证了运行机理的正确性。     

Bacterial Foraging Based Optimal Design of Transverse Flux Linear Motor for Thrust Force Improvement

Abstract—This article presents a novel optimal design for a permanent magnet excitation transverse flux linear motor with an inner mover using bacterial foraging optimization. The target is maximizing the motor thrust force, which is the most important quantity in linear electric drives. The stator pole length, air-gap length, winding window width, and stator pole width define the search space for the optimization problem. The response surface methodology is used to build the mathematical model of the motor thrust force in terms of the design variables. It can create an objective function easily, and great computational time is saved. Finite-element computations are used for numerical experiments on the geometrical design variables to determine the coefficients of a second-order analytical model for the response surface methodology. The bacterial foraging optimization technique is used as a searching tool under the constraints of design variables for design optimization of the transverse flux linear motor to improve the motor thrust force. The effectiveness of the proposed bacterial foraging optimization model is then compared with that of both genetic algorithm and particle swarm optimization models. With this proposed bacterial foraging optimization technique, the thrust force of the initially designed transverse flux linear motor can be increased.     

横向磁场磁通切换电励磁磁悬浮直线电机的研究

在传统磁通切换直线电机的基础上,提出了一种可用于轨道交通的横向磁场磁通切换电励磁磁悬浮直线电机（TMFFSEEMSLM）。研究TMFFSEEMSLM的结构与运行原理,该电机的定子为U形磁极,动子为双H形并通过横梁连接,产生横向磁通进行导向,电枢绕组和励磁绕组均位于电机短初级上实现磁通切换,次级仅由导磁铁心构成,电励磁实现气隙磁场调节,极大地降低了远距离轨道交通的制造成本,磁悬浮使电机的初级和次级实现无摩擦运动;建立该磁悬浮直线电机的数学模型,推导电压、磁链方程以及悬浮力、电磁推力和导向力的解析表达式;建立电机的三维有限元模型,分析电机的磁场分布及其电磁参数,对电机的悬浮力、电磁推力、导向力进行仿真,研究结果验证了电机结构的可行性,可以实现牵引、悬浮与导向的一体化。     

开关磁阻直线电机的设计及其推力优化

设计了一种开关磁阻直线电机,使用JMAG软件对其进行了仿真和优化。进行了推力公式的推导,研究了导通顺序和初始位置对电机推力的影响,并分析了三种典型情况的磁力线分布。对电机的定子和动子的齿部和轭部高度、宽度及铁耗进行仿真优化,得出了最优参数。将有取向硅钢应用于该电机,研究了推力与轧制角的关系,并与使用普通硅钢的开关磁阻直线电机进行了对比,推力有一定提升。提出在动子齿部开切向槽的方案,结果表明,开切向槽对推力的影响较小,并能显著减小推力波动。     

一种新型直线超声波电动机的设计

研制了一种新型直线超声波电动机，电机采用面内振动的形式。以层叠式压电陶瓷材料作激振元件，通过ANSYS有限元软件对电机的结构尺寸进行了相应的计算，确定出了电机的结构尺寸，随后对电机的装配进行了设计。经实测，电机的最大无负载速度可达110mm／s，最大输出推力3．7N，达到了预期设计的目的。     

一种新型直线超声电动机设计

新型直线超声电动机采用面内振动的形式,以层叠式压电陶瓷材料作激振元件。通过ANSYS有限元软件对电机的结构尺寸进行相应计算,并对电机装配进行了设计。经实测,电机的最大无负载速度可达110mm/s,最大输出推力3.7N,达到了预期的目的。     

高压断路器新型电机操动机构的动态特性分析

研究了两种高压断路器新型电机操动机构,设计分析了两种电机操动机构及其运动特性.根据40.5 kV户内真空断路器的操作特性要求,研究了永磁直线直流电机和有限转角永磁无刷直流电机操动机构.对两种电机的结构和特性参数进行的初步的设计,同时利用有限元方法对两种电机的基本特性和起动过程进行了动态特性仿真,得到了电机运行时的电磁推力、电流、速度等曲线.通过有限元的仿真结果的分析,一方面调整了电机设计参数,最终得到符合操作特性要求的电机操动机构;另一方面表明两种电机操动机构在起动性能、运行方式及机构的复杂性、控制方面等方面特点,为高压断路器采用电机操动机构提供了可靠的依据.     

高压断路器新型电机操动机构的动态特性

研究一种高压断路器新型电机操动机构,设计分析永磁直线直流电机及其运动特性。根据40.5kV真空断路器机械特性的要求,设计了一台配有制动保持装置的电机操动机构。利用有限元方法建立电机操动机构的仿真模型,对永磁直线直流电机的基本特性和起动过程进行动态特性仿真,得到了电机运行时的电磁推力、电流、速度等曲线,并进行了分析。结果表明,电机操动机构能够提供足够的合分闸速度,满足真空断路器开断和关合的要求。     

Mover design and simulation of linear synchronous motor with half‐wave‐rectified self‐excitation

This paper presents a design method for a linear synchronous motor with half‐wave‐rectified self‐excitation; this method enables the construction of a motor with small thrust ripple. The mover of the motor is designed to be asymmetrical in order to reduce the thrust ripple. First, we design the configuration of the asymmetrical mover and the field winding of the mover by using the finite element method and a characteristic equation. The asymmetrical mover is built, and the thrust ripple reduction is verified by experiments. Next, the linear synchronous motor is modeled using a circuit simulator in order to confirm its high‐speed performance. The operation characteristics are clarified by simulation. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 43–52, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21051     

单模态纵-弯复合直线电动机的机理与特性

提出了一种融合一阶纵振和四阶弯曲振动模式的单模态直线超声波电动机,介绍了电动机的结构和运行机理,利用有限元方法建立了电动机定子的机电耦合模型,仿真分析了电动机定子的振动特性,确定了电动机定子工作模态和工作频率;利用弹性杆的纵振动和悬臂梁的弯曲振动理论建立了电动机驱动足椭圆运动轨迹方程,分析了激励电压相位差对电动机椭圆轨迹的影响;利用粘弹性接触机理给出了电动机的机械特性输出曲线,分析了预压力、激励电压幅值和激励频率等对电动机输出特性的影响。通过数值和仿真分析得出:单模态直线超声波电动机的工作频率为39 860 Hz,在外加激励电压Up-p=100 V时,电动机最大输出推力和空载速度分别达到19.1 N和310 mm·s~(-1)。     

A 3‐DOF Inchworm Using Levitation Caused by Vertical Vibration

We propose a 3‐DOF inchworm‐type microactuator that uses levitation generated by vertical vibration. The vertical vibration is created by a piezoelectric actuator. The inchworm typically consists of thrust elements and clamp elements. The proposed inchworm, however, does not use any clamp elements. Four levitation elements are connected with four thrust elements, which are stacked‐type piezoelectric actuators. The levitation element consists of a mass, a piezoelectric actuator, and a plate. The vertical vibration of the piezoelectric actuator lifts the levitation elements, which eliminates any friction. By controlling the order of the deformation of the horizontal piezoelectric actuators and the vibration of the vertical piezoelectric actuators, the inchworm engages in linear and rotational motion. The levitation height and the linear and rotational displacement of the inchworm were measured. Experimental results demonstrated the feasibility of the proposed 3‐DOF inchworm. The mechanism described in this paper is effective for a precision positioning system in a clean room.