Rotary scanning wireless temperature measurement method for hyperthermia using ferromagnetic implants

Recently, the use of a ferromagnetic material in a soft‐heating method has garnered much attention as a novel method for cancer treatment. By concurrently using this material as a thermal probe, we are currently developing a minimally invasive heating and wireless temperature measurement system. To make the approach feasible in a clinical setting, it is vital to overcome the key challenge of heating the local tumor at a constant temperature. In previous conventional approaches, it was necessary to switch the induction‐heating power supply on/off after the target tumor temperature was reached. However, it cannot determine the temperature of the material during the power‐off period. Therefore, we changed this approach and found that by adjusting the distance between the heating coil and the material while maintaining a constant current flow in heating coil, the drift problem, which happened just after power is supplied during the on/off operation, did not occur any longer. Accordingly, it was not required to use multiple sensors to reduce the drift, thereby minimizing the cost. This study verifies the validity of our wireless thermometry approach while performing rotary scanning and proposes a technique for determining achievement of the target temperature. This knowledge complements other approaches for cancer treatment utilizing hyperthermia. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

用于靶向热疗实验的交变磁场系统研制

本文构建了用于磁颗粒靶向热疗的实验平台并进行了磁小体加热实验.在分析实验要求的基础上,文中首先提出了高频磁场发生装置的设计方案,设计制作了 C 型磁体,搭建了频率和幅值可调的高频激励源.随后利用自制磁场测量探头对各频率点的磁场强度及其分布均匀性进行测量,对该实验平台的性能指标进行了初步评估.最后通过对含有趋磁细菌AMB-1的磁小体和磁流体进行加热实验,证明了磁小体具有较好的产热率和加热效果,为进一步的实验研究打下了基础.     

考虑磁路饱和的开关磁阻电机无位置 传感器控制方法

开关磁阻电机在磁路饱和情况下,其导通相电感会随导通相电流的变化而变化,从而影响转子位置估算精度,提出一种电机转子位置估算方法。首先建立了相电感函数关系式;然后分析了相电流与相电感极值定位点位置角之间的关系;最后阐述了由两相邻采样定位点来估算出相应的转子位置角度的实现过程。以三相6/4结构电机进行了相关仿真与实验,结果表明上述方法的可行性。     

永磁同步电机初始磁极位置检测方法

根据永磁同步电机相电感的饱和效应,提出了一种恒压源作用下的相电流响应来获得电机初始磁极位置的检测方法,并针对制动器打开瞬间容易出现因磁极位置不准而造成无法定位的问题,对位能性负载提出了一种基于位置环的快速定位法。该方法根据电机实际转动的角度来反向移动给定电流矢量,实现快速定位。最后通过计算不同幅值电流矢量二次定位转过的角度来获得精确的磁极位置。所提方法能够准确获得电机初始磁极位置,可适用于不同类型的永磁电机。实验证明:该控制方法结构简单,易于数字控制实现,同时具有较强的通用性和鲁棒性。     

正方形亥姆霍兹线圈三维磁场及其均匀性分析

为研究光纤陀螺的磁敏感性,利用三个正方形亥姆霍兹线圈构建三维匀强磁场,并分析其匀强磁场区域特性。将正方形亥姆霍兹线圈视为四段载流导线,采取分段计算然后进行矢量叠加的方法,分析了正方形亥姆霍兹线圈三维空间磁场强度及其均匀性,并给出仿真结果。最后给出了正方形亥姆霍兹线圈三维匀强磁场的结构模型及相关数据分析。     

胶囊内窥镜新型外磁场驱动系统模型与仿真

为了克服传统推进式和被动式内窥镜在医用检查时存在的不足,提出了一种由三个同轴圆线圈和两对平行鞍线圈组成的胶囊内窥镜新型外磁场驱动模型。胶囊内窥镜内部嵌入NdFeB永磁体,通过控制外部线圈的电流来驱动永磁体,带动内窥镜在体内运动。在实验过程中,运用ANSOFT电磁场仿真软件分别对三个同轴圆线圈和鞍线圈的磁场分布进行了分析,结果表明,该模块能够产生三维匀强磁场,符合驱动无线胶囊内窥镜在体内运动的要求,并且结构简单紧凑,可控性高,有利于提高检测效率。     

A novel magnet polarity identification method for initial position estimation for sensorless IPMSM drive

This paper proposes a novel magnet polarity identification method for initial position estimation during startup for interior permanent magnet synchronous machine (IPMSM) drives. The rotor's initial position estimation is based on magnetic saliency and employs high‐frequency (HF) components of the voltage and current that are excited by the multi space‐vector pulse‐width modulation (MSVPWM) pattern. However, there is a common trouble in the estimation methods based on the magnetic saliency: it is necessary to identify the magnet polarity in order to distinguish the north and south poles since the estimated position angle is a periodic function with π radians. In this paper, a novel inductance estimation method is presented and the magnet polarity is uniquely identified by the relationship between the estimated inductance and the magnetic saturation effect. Experimental results confirm the advantages of the proposed method: it is reliable, accurate, and convenient, and can be done in real time. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于矩形亥姆霍兹线圈的大均匀区改进型三维磁场发生器设计与特性

为了克服传统磁场发生器空间利用率低的缺陷,提出了改进的三维磁场发生器,具有结构紧凑、更大的均匀区。相比传统的亥姆霍兹线圈,每个维度引入了一双辅助线圈。要设计这紧凑场发生器,五个模型参数需要根据用户的要求对均匀性进行优化。最后,研发了一台磁场发生器,用于测试新型线圈的性能以验证其设计方法。实验结果表明,测试的磁场结果与设计值吻合得很好,最大的设计偏差仅为0.12%。更重要的是,产生相同体积的均匀区,这种磁场发生器的体积仅为传统亥姆霍兹线圈的1/13.6。     

单层方体四线圈均匀磁场源理论计算与仿真

一个可以产生已知强度的均匀磁场区的标准磁场源是测试、标定各类磁测仪器的基本条件。以正方体四线圈作为均匀磁场标准场源,理论推导了其磁场分布。通过Maxwell软件对正方体四线圈的磁场进行仿真分析,仿真结果与理论计算一致。分析了四线圈装置轴向和垂直轴向的磁场均匀性,结果表明方体四线圈装置可以在装置中心周围相当大的范围内产生高均匀度的磁场。对于边长为1m的四线圈装置,在装置中心长宽0.2m、高0.4m的长方体内,磁场偏差率控制在0.25%以内。结果论证了其作为均匀磁场源的可行性,与亥姆霍兹线圈相比,无论在均匀度方面还是在均匀场区大小方面都有很大优势。     

无人直升机轴频磁场信号检测方法研究

轴频磁场信号是无人直升机在机动飞行时产生的一种重要物理场,是一种难以被隐藏的目标特征信号.通过分析轴频磁场信号能实现对无人直升机的检测和识别,并能监测其运动状态.利用磁场传感器采集无人直升机的轴频磁场信号,并利用短时傅里叶变换算法对实测数据进行时频分析.实测结果表明,无人直升机在机动飞行中能产生特定随运动状态变化的5～40 Hz的轴频磁场信号.通过对该特征信号的提取,实现了对无人直升机的准确检测和识别,该探测方法在实测数据的应用中取得了良好的效果.     

Experimental studies on a structure of eddy current probe for detection of magnetic flux distorted by a flaw

Bobbin-coil-type eddy current probes, which are conventionally used for nondestructive inspection of steam generator tubes in pressurized-water-type nuclear power plants, have poor detection sensitivity to circumferential flaws. Hence a new type of eddy current probe was proposed to effectively detect the magnetic flux component that is indicative of a flaw and thus to eliminate the dependency on sensitivity in flaw detection. In the course of development of the proposed method, probe structures were investigated based on the measurement of magnetic fields induced by variously-shaped excitation flat coils. The new type of probe proposed here consists of differential pick-up coils detecting magnetic flux and excitation coils having a parallelogrammic shape. The structure of the coils was fabricated in order to detect flaws independently of their directions in trial. Nondestructive flaw detection tests were then conducted with the probe. The results obtained concrete evidence showing that both the horizontal, the vertical slit-flaws and even the small hole of 0.5 mm in diameter can be detected successfully.     

Design of a coil geometry for generating magnetic field to evaluate biological effects at 85 kHz

In recent years, the use of induction‐heating systems has increased and wireless power transmission (WPT) systems have been discussed. These applications are installed close to a human body. Therefore, it is important to discuss the effects of alternating magnetic fields and to evaluate electromagnetic interference. This paper discusses the design procedure of a magnetic field generator to evaluate the electromagnetic interference at 85 kHz that is being studied in WPT systems for EV and HEV. The magnetic field generator presented in this paper consists of a single‐phase inverter circuit that uses SiC‐MOSFETs and an air–core inductor that is used as the coil for generating a magnetic field. In particular, this paper shows that the coil used for generating magnetic field needs to reduce the winding voltage to generate higher magnetic flux. In addition, this paper presents the design procedure of the proposed coil structure that can satisfy some limited conditions. The experimental results of the proposed system rated at 82 kHz and 100 A are presented.     

东锅W火焰锅炉燃烧调整方法探讨及试验研究

总结分析东锅W火焰锅炉燃烧系统的特点,在600MW和300MW机组锅炉试验基础上详细探讨了各种燃烧调整方法对锅炉稳定性和经济性的影响,结果表明通过合理的燃烧调整可使锅炉的稳定性及经济性大幅提高。     

基于可疑度的电网参数错误辨识与估计方法

电网参数错误会给状态估计、坏数据辨识带来不利的影响,并降低能量管理系统中其他高级应用软件的实用化程度。本文提出了一种基于综合可疑度的电网参数错误辨识与估计方法,首先通过可疑测点评价函数确定可疑测点集合,根据支路关联距离的概念对可疑测点评价函数值进行加权,计算支路参数错误综合可疑度,然后按照综合可疑度指标大小的顺序,逐一排查可疑支路的可疑参数,最终将错误参数的最优估计作为一个优化问题求解。算例仿真结果表明,本文提出的方法能够准确有效地辨识电网参数错误并对其进行最优估计,可有效提升电网运行参数的准确性。     

Position and speed sensorless control for IPMSM based on estimation of position error

In most variable‐speed drives of PMSM, some type of shaft sensor such as an optical encoder or resolver is connected to the rotor shaft. However, such sensor presents several disadvantages such as drive cost, machine size, reliability, and noise immunity. Therefore, the sensorless control of PMSM is desired and various sensorless control strategies have been investigated. This paper presents a novel sensorless control strategy for an interior permanent magnet synchronous motor (IPMSM). A new model of IPMSM using an extended electromotive force (EMF) in the rotating reference frame is utilized in order to estimate both position and speed. The extended EMF is estimated by the least‐order observer, and the estimation position error is directly obtained. The proposed scheme corrects the estimated position and speed so that the estimation position error becomes zero. The proposed system is very simple and the design of the controller is easy. Several drive tests are carried out and the experimental results show the effectiveness of the proposed sensorless control system. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 43–52, 2003; Published online in Wiley InterScience ( www. interscience.wiley.com ). DOI 10.1002/eej.10180     

磁性材料三维磁特性传感信号检测技术中关键问题的研究与分析

精确模拟磁性材料实际工作状态下的磁特性对于提高电机、电力变压器等电工设备的性能和效率具有重要意义。为了全面解析磁材料磁特性,提出了三维磁特性测试方法,并针对三维磁特性传感信号的检测问题进行了深入研究。设计了新型三维B-H传感线圈与传感箱并分析了三维传感线圈的校准标定等难点问题,讨论了测试过程LabVIEW运算中在三维激励条件下的积分漂移和采集中的杂波干扰等关键性问题,并提出解决方案。实验证明,所提出的解决方案是有效的,具有可行性。     

基于磁场检测与多判据融合的架空线路接地故障定位方法

针对当前配电网故障区段定位难的问题,提出了一种基于故障点前后磁场差异的故障定位新方法。首先,分析了杆塔处x轴与y轴磁场的分布及其与相电流的关系,同时考虑了三相导线排列差异与数据窗长短对磁场的影响。其次,通过故障点上下游x轴与y轴的磁场差异作为定位依据,分别从不同角度对双轴磁场进行相似度分析,由此构建5种定位新判据。最后,将5种定位判据通过D-S证据理论进行融合,将概率最大的区段判定为故障区段。所提方法综合了各判据的优势,克服了单一判据的适应性问题。通过对高阻故障、噪声干扰等多种工况进行仿真测试,验证了所提方法的有效性。     

三维正弦电磁场问题中一类和周期性边界条件的处理方法

用三维有限元法计算电机中的磁场问题时,求解区域中经常同时包含周期边界条件和第一类边界条件两种强加边界条件,通常情况是分别处理,这样不仅使程序处理复杂,而且也增加了计算时间。本文提出了一种强加边界条件的统一处理方法,使两种边界条件能同时处理,简化了程序编制,并以A,φ-4三维有限元法为例导出了离散格式,讨论了相应的矩阵存储技术,为三维有限元法的工程实际应用打下了基础。     

同轴式磁力齿轮试验样机的参数优化与设计改进

针对一台传动比为-15/7的同轴式磁力齿轮试验样机存在转矩密度偏低的问题,运用二维有限元法分析调磁极片的径向齿高、相对齿宽、连接桥位置及内外磁体充磁方式、磁体体积对转矩密度的影响,从而来寻找提升转矩密度的措施。结果表明,在不增加制造成本的前提下,通过改进调磁极片和磁体的相关参数使转矩密度提升43%,磁力齿轮外径缩小7.5mm。     

汽轮发电机在饱和与磁场畸变时负载励磁电流计算的新方法

磁路饱和与磁场畸变的共同作用会使发电机负载饱和特性显著偏离其空载特性,为了计算这种差异,提出了其负载励磁电流计算的一种改进方法.以300 MW汽轮发电机为例,以有限元方法为工具,获得了反映磁路饱和与磁场畸变共同作用下负载非线性特性的关系曲线族,提出了用这种新曲线族代替空载特性计算负载励磁电流的新方法.通过计算发电机在不同功角下的负载励磁电流,说明该方法比传统方法有较高的计算精度,比有限元方法有较快的计算速度.