双转子永磁缓速器的设计与输出特性分析

通过对转子轴向移动式无级变矩永磁缓速器工作原理的研究,提出一种鼓式双转子永磁缓速器结构设计方案。根据设计目标以及车辆制动法规要求,基于永磁制动理论,采用MATLAB辅助设计确定了双转子永磁缓速器关键结构参数。通过ANSYS EM三维电磁场瞬态仿真模块,建立有限元仿真模型,对缓速器输出的制动力矩输出进行仿真分析,验证其在不同工作模式下的制动力矩,研究双转子完全工作状态下转子的转速与输出制动力矩的关系、输出制动力矩的调节特征。研究表明：所设计的永磁缓速器的制动力矩输出满足车辆的要求,其输出的制动力矩具有无极线性调节特性,还有性能提升空间。     

基于遗传算法的车用永磁式缓速器设计优化方法

永磁式缓速器是一种新型行车辅助制动装置.提出永磁式缓速器的多学科概念分析模型,分析电磁场参数、结构参数和温度参数等多学科对缓速器整体性能的影响;以缓速器的制动力矩最大为优化目标,设计变量包括永磁体周向宽度和轴向长度、永磁体个数、转子鼓内半径、转子鼓厚度、气隙.约束条件是许用温升、软磁材料饱和磁通量密度和结构几何关系.利用遗传算法对设计模型进行全局优化,获得初步的设计变量优化数值.文中的多学科设计优化方法是有效的,可用于工程设计.     

用ANSYS实现电涡流缓速器转子盘的温度分析

电涡流缓速器在制动过程中,其转子盘上会产生大量的热量。如果热能不能很好的散发出去,将会使缓速器温度升高,而温度的升高将削弱转子盘的导磁性能。对铁质材料,其居里点是770℃,超过这个温度,材料将失去导磁性能。因此对电涡流缓速器转子盘进行温度分析很有必要。这里用有限元软件ANSYS8.0分析了电涡流缓速器转子盘的温度场,结果证明在正常行驶情况下具有良好散热结构的转子盘,其温度不会过高。     

基于Halbach阵列的永磁缓速器结构优化与仿真

为了进一步减小永磁缓速器的尺寸,提出一款基于Halbach阵列的永磁缓速器,永磁铁采用Halbach阵列后使缓速器中气隙的磁密强度大,制动力矩增加.建立永磁缓速器优化模型,优化后的径向尺寸明显降低.利用Maxwell软件对缓速器进行制动力矩和涡流场的仿真分析,进一步证明了Halbach式永磁缓速器优于常规永磁缓速器.将...     

电动汽车用ISG永磁电机在弱磁条件下的永磁体涡流损耗分析

针对内转子内置式永磁同步电机在高速运行时转子永磁体所产生温升严重的问题,以"一"型和"V"型两种不同磁极结构的35kW永磁同步电机为研究对象,在永磁体总量和磁极分块相同的情况下,利用有限元法与解析法,分析了两种磁极结构在弱磁条件下永磁体表面的磁通及其变化情况,探究了两种磁极结构的电机在相同的弱磁条件下不同转速、不同弱磁角和不同去磁电流时的转子永磁体涡流损耗大小和特点,得到在相同弱磁条件下"V"型磁极结构的永磁体涡流损耗大于"一"型磁极结构的结论。最后制造样机并进行试验,验证了有限元模型的有效性,为永磁同步电机在弱磁条件下的永磁体涡流损耗情况提供参考。     

永磁式涡流缓速器涡流分析与制动力矩计算

介绍了永磁式涡流缓速器的结构与工作原理.考虑了涡流透入深度,运用电磁场理论推导了永磁式涡流缓速器的涡流密度表达式;采用磁路方法,将涡流去磁效应折算到永磁铁上,根据涡流损耗原理推导了永磁式涡流缓速器制动力矩计算公式,该计算公式反映了永磁式涡流缓速器各设计参数的相互关系,且理论计算值与台架试验值基本吻合,说明该方法是可行的,可用于指导永磁式涡流缓速器产品的设计和开发.     

可辅助制动永磁变速器的设计与研究

永磁变速器与永磁缓速器结构相似原理相同,为使两者的功能在同一机械上实现,提出了一种可辅助制动的永磁变速器新结构,推导了永磁变速器的磁转矩方程,结合MATLAB探究了变速器的耦合、变速及辅助制动能力。结果显示磁转矩受永磁体磁极对数、永磁体厚度、磁阻等因素的影响,变速时的转速差越小,效率越高,制动时的减速度受从动盘初始转速的影响且最大可达9m/s2。最后通过ANSYS软件分析了主从动盘的变形情况,论证了可辅助制动永磁变速器的可行性。     

电涡流制动的工作原理及其在汽车上应用

传统的汽车摩擦制动器制动时热衰退性明显,并且会产生制动粉尘和噪声,影响制动器的安全性并污染环境。电磁制动是非接触式涡流制动,具有响应时间快、制动平稳、控制方便、无制动粉尘和噪声产生等特点,所以电磁制动将会越来越广泛地应用到汽车上。首先对电涡流制动技术的工作原理与分类进行了介绍,在此基础上阐述了电涡流缓速器和永磁缓速器的结构原理与性能特点,最后着重对电涡流制动技术的发展趋势进行分析,指出电涡流制动的轻量化、集成化和节能化将是今后的技术发展方向。     

双笼式永磁涡流联轴器温度场有限元仿真研究

基于鼠笼式异步电动机原理及结构特性,提出一种双笼式永磁涡流联轴器结构,其具有启动性能好、传递性能良好等优点。从温度场角度出发,研究联轴器在工作状态下内部温度分布规律。有限元分析结果表明:联轴器温度场整体呈区域性分布,最高部分发生在内转子,可达79.163℃,外转子永磁体最高温度为30.48℃,未达到材料居里温度,联轴器可保证正常工作。分析结果对双笼式永磁涡流联轴器进一步的性能研究具有一定的指导意义。     

汽车联合制动系统制动力分配的优化控制

在电涡流缓速器和汽车主制动器构成的联合制动系统中,设定了电涡流缓速器转子盘温度的限制条件,建立了联合制动系统制动力分配的优化模型,计算出制动力分配系数与道路坡度的变化曲线,拟合了两者间的指数函数关系。虚拟多坡度道路上制动过程的验证结果表明,随道路坡度变化的制动力分配系数能实现电涡流缓速器与主制动器的有机联合,使联合制动系统在长下坡道路上持续有效地工作,能充分发挥电涡流缓速器的辅助制动作用。     

Three-dimensional electromagnetic analysis and design of permanent magnet retarder

An eddy current retarder for vehicles generates much heat when it works continuously, which leads to serious decline in braking torque. This paper proposes a novel permanent magnet retarder (PMR) for vehicles, whose cooling system connects with engine cooling-water. A three-dimensional finite element model is developed to model the electromagnetic behavior of a permanent magnet retarder under a constant speed. The magnetic field and eddy current field in PMR are numerically solved by a finite element method. By accounting for the nonlinear permeability of the rotor and the weakened effect in the magnetic field that is generated by the eddy current magnetic field, the calculation accuracy of air-gap magnetic field is enhanced. Experiment shows that the temperature of the retarder is less than 150°C, and the braking torque keeps the hard characteristics curve. The calculated air-gap magnetic flux density is fairly good agreement with the measured one.     

电涡流缓速器的结构参数对磁场影响的研究

对某一车用电涡流缓速器进行了设计,确定了相应的结构尺寸;并以此结构尺寸为基础,分析研究了电涡流缓速器结构参数变化对磁场的影响程度,为其结构设计提供重要依据.     

永磁电机退磁电流的仿真与测试

受外磁场、温度场、化学反应、机械振动等因素的影响,永磁电机在运输或工作过程中可能发生不可逆退磁.论文以样机为例,通过有限元的计算和分析,给出了电机退磁电流的计算方法,仿真结果可以以图表或图形等多种方式给出,直观、简洁、易于理解.另外论文还介绍了一种退磁电流的测试方法,结合磁场的有限元分析对永磁电机的退磁电流进行分析,通过验证试验结果与有限元分析非常吻合.为了保证电机在生命周期内的正常运转,在电机设计时应保证永磁体在最严酷的工作环境中各部分的最大去磁工作点应高于拐点位置.     

Development of eddy current microscopy for high resolution electrical conductivity imaging using atomic force microscopy

We present a high resolution electrical conductivity imaging technique based on the principles of eddy current and atomic force microscopy (AFM). An electromagnetic coil is used to generate eddy currents in an electrically conducting material. The eddy currents generated in the conducting sample are detected and measured with a magnetic tip attached to a flexible cantilever of an AFM. The eddy current generation and its interaction with the magnetic tip cantilever are theoretically modeled using monopole approximation. The model is used to estimate the eddy current force between the magnetic tip and the electrically conducting sample. The theoretical model is also used to choose a magnetic tip-cantilever system with appropriate magnetic field and spring constant to facilitate the design of a high resolution electrical conductivity imaging system. The force between the tip and the sample due to eddy currents is measured as a function of the separation distance and compared to the model in a single crystal copper. Images of electrical conductivity variations in a polycrystalline dual phase titanium alloy (Ti-6Al-4V) sample are obtained by scanning the magnetic tip-cantilever held at a standoff distance from the sample surface. The contrast in the image is explained based on the electrical conductivity and eddy current force between the magnetic tip and the sample. The spatial resolution of the eddy current imaging system is determined by imaging carbon nanofibers in a polymer matrix. The advantages, limitations, and applications of the technique are discussed.     

InSb磁敏电阻脉冲涡流传感器的研究

脉冲涡流检测方法是涡流检测技术的一个新兴分支。因脉冲信号频带很宽,比单一频率正弦涡流衰减慢,其瞬态感应电压信号中就包含了有关缺陷的重要信息。本文分析了InSb磁敏电阻作为脉冲涡流检测元件的工作原理,设计了探头结构和调理电路,有效抑制了环境温度的干扰,并分析了应用InSb磁敏电阻的涡流探头检测金属裂纹特征的信息提取方法。实验结果表明,采用InSb磁敏电阻作为脉冲涡流检测传感器,具有较高的裂纹灵敏度,且可以较好地反映裂纹的深度。     

电涡流传感器仿真开发与缺陷无损检测实验研究

金属表面缺陷电磁场分布情况是影响电涡流探测器灵敏度的主要原因。采用有限元方法和ANSYS工具,建立了电涡流探测器仿真过程中的有限元建模、材料特性定义、网格划分、边界条件设置、模型加载及模型求解等算法,对电涡流的电磁场分布进行仿真分析,并辅助设计电涡流探测器的线圈形状结构以及工作频率对传感器灵敏度的影响,并进行了实验研究,该技术可行,可指导电涡流探伤传感器优化设计和近表面缺陷无损检测。     

涡流效应影响高速运动钢管磁化的仿真研究

根据楞次定律,在高速漏磁检测过程中钢管与轴向磁化线圈发生轴向相对运动时将产生涡流效应。涡流磁场与原磁化场叠加后影响钢管磁化状态,最终影响到高速漏磁检测结果的一致性。为分析高速漏磁检测中涡流效应对钢管全长磁化的影响,将原磁化场矢量分解轴向分量和径向分量并根据楞次定律建立钢管内部涡流分布方程,并获得感应涡流磁场在钢管中的空间分布。分析涡流磁场叠加于原磁化场之后对管头、管体和管尾处磁化状态的影响,发现管头涡流磁场与原磁化场方向相反,涡流效应具有抑制钢管磁化作用;管尾处两者方向相同,涡流效应具有增强磁化作用;涡流效应对管体磁化基本没有影响。通过有限元法分析钢管运行速度与涡流密度的关系,并进一步研究涡流效应对钢管管头、管体和管尾磁化状态的影响,为钢管全长一致性评价提供参考依据。     

径向电涡流阻尼器对柔性转子系统振动的控制

为了抑制转子系统的振动和研发高性能的转子系统振动主动控制执行元件,基于电涡流原理提出了一种新型的转子系统径向电涡流阻尼器,在一个带有双盘的柔性转子系统上详细地测量了不同磁场强度条件下径向电涡流阻尼器支撑的转子系统在非旋转状态下的传递函数、在恒定转速下的运动轨道以及在慢加速运行过程中的不平衡响应曲线,并进行了利用径向电涡流阻尼器对转子系统的振动进行分段和比例控制的有效性试验。结果表明了这种新型的径向电涡流阻尼器不仅具有结构简单、无需流体介质、无机械接触等特点,而且其动力特性还容易控制,在设计合理的条件下能够显著地减小转子系统的振动,是一种被动和主动兼备具有良好发展和应用前景的转子系统阻尼结构。     

New version of performance demonstration program for steam generator tubing analysts

The reliability and performance of steam generators (SGs) are serious concerns in the operation of nuclear power plants. In particular, SG tubing is subject to a variety of degradation processes that can lead to potential leakage or rupture. To prevent a plant shutdown from this kind of event, the integrity of SG tubing should be periodically determined. The eddy current test is widely used for the inspection of SG tubing during in-service inspection. For the evaluation of eddy current data, analysts are required to have the Level II or greater qualification based on the american society for nondestructive testing (ASNT) standard. In addition, analysts evaluating eddy current data obtained from SG tubing are required to have a qualification of performance demonstration. The performance demonstration program in Korea has existed since 2004 and uses the qualified data analyst (QDA) program developed by the electric power research institute (EPRI). Recently, the QDA program was updated by EPRI. The updated QDA program has been in effect for SG tubing analysts in Korea since 2010. In this paper, we describe the performance demonstration program, the degradation mechanisms, and the inspection techniques for SG tubing in nuclear power plants.     

Effect of a gap in the electromagnet-object magnetic circuit on the magnetic field of surface flaws in different steels

The dependences of the magnetic-field strength of surface flaws in various steels on the electromagnet current have been studied for different gaps in the magnetic circuit. It is shown that an anomalous ratio of the magnetic-field strengths of flaws in hard and soft magnetic materials holds in the entire range of gap changes. The dependence of the ratio of the magnetic-field strengths of a flaw, which are obtained for different gaps in the magnetic circuit, on the electromagnet current has an extremum in the region of weak currents and, at high currents, tends toward to a constant value, which is determined by the value of the set gaps. The results are considered, taking their interrelations with the magnetic properties of materials and processes of their magnetization in the presence of a demagnetization factor into account.