直流电动机电刷寿命

本论述了电刷寿命，电刷磨损原因以及获得电刷较长寿命所能采取的措施。为了能确认和避免这方面的问题和解决存在的问题，就要使人们认识到造成电刷磨损的因素和条件，然而，本并不是一本关于如何确定问题的说明书，为有助于碳刷和换向问题的解决，应与电机制造商取得联系，中内容适用于大，中型工业直流电动机和发电机。     

延长永磁直流电动机寿命的途径

电机寿命的长短,是电机性能的一项重要经济性指标。连续工作永磁直流电机的寿命可达数百小时,而重复短时工作电机的累积工作时间只能达数十小时,如美国汽车公司标准AM15022规定汽车用洗涤电动机工作寿命为10,000次循环,每次循环工作5秒,累积工作时间仅14小时。如何延长此类电机的工作寿命。本文在分析电机运行特点的基础上,指出影响寿命的主要因素,提出延长寿命的措施。     

用交流励磁电压测定直流电动机电刷中性线的方法

针对某电厂汽轮机直流油泵电动机因电刷位置不当造成换向不善最终导致电刷烧损的实例,对确定直流电动机电刷中性线位置的方法进行了讨论。提出采用交流电源对电动机励磁绕组进行励磁从而确定中性线位置的方法。     

直流电动机电刷、换向器接触问题的分析

换向器、电刷装置是电动机中的动接触元件、其接触性能的好坏对电动机的运行可靠性和使用寿命影响很大，本文详细分析了在生产过程中产生换向器，电刷接触问题的主要因素及解决的基本对策方法。     

稀土永磁无刷直流电动机的应用与市场前景

永磁无刷直流电动机用电子换向替代了电刷和换向器,可以实现高性能、高可靠性、长寿命、免维护的目的。永磁无刷直流电动机是集交流电动机和直流电动机优点于一体的机电一体化产品。     

无刷直流电动机的设计(Ⅰ)

随着永磁材料和功率电子元器件的不断进步,永磁无刷直流电动机得到了快速的发展,它们被广泛地用于变速驱动、伺服驱动、兵器、航空、航天和工业自动化等各个领域。因此,合理正确地设计永磁无刷直流电动机是一个越来越重要的课题。从本期起分期介绍无刷直流电动机的设计,主要有:无刷直流电动机的结构和工作原理,以及连接方式;分数槽绕组;磁路计算;电路系统的计算等内容;最后介绍了两个典型例题。     

直流电动机电刷、换向器接触问题的分析

换向器、电刷装置是电动机中的动接触元件 ,其接触性能的好坏对电动机的运行可靠性和使用寿命影响很大。本文详细分析了在生产过程中产生换向器、电刷接触问题的主要因素及解决的基本对策方法     

永磁直流电动机振动和噪声分析

详细介绍了在生产过程中引起永磁直流电动机振动和噪声的主要原因及解决的基本方法.     

无刷直流电动机的最佳触发位置选择

从有刷直流电动机的绕组模型出发，探讨１８０°通电型和１２０°通电型三相无刷直流电动机最佳触发位置的选择，并给出了最佳换向逻辑。     

电动机振动的分析

转子的机械不平衡及安装、连接不良是造成电机振动的一个主要因素．文中详细介绍了在生产过程中引起转于动平衡不合格的主要原因及解决的基本对策方法。同时介绍了在进行电动机的安装连接时应注意的事项。     

超声波电机定子振动模型的一维解析

在简述了行波型超声波电机工作原理的基础上,重点讨论了该类型电机定子的一维振动模型,由此对超声波电机的振动特性进行了数值计算。最后对所计算的样机进行了实验,并将其与数值计算结果进行了比较,证实了所提方案的准确性。     

Magnetostriction and motor vibration

A quiet induction motor is strongly demanded today. Electromagnetic factors are a main cause of vibration and acoustic noise in a small induction motor. Electromagnetic forces and magnetostrictive forces are considered as the origin of electromagnetic vibration and noise. In this paper, magnetostrictive vibration of a ring of electrical steel sheets was simulated by the mechanical finite element method. Magnetostriction was assumed as external forces and they were added at each node of the meshed ring. Resonant frequency and the mode of the ring were calculated. In the steel sheet ring excited by a PWM voltage source inverter, the frequency spectrum of vibration of ring was measured and compared with the calculated results. It was confirmed that these procedures simulated magnetostriction behavior of electrical steel sheets. Furthermore, the electromagnetic forces of a small induction motor were calculated and compared with the magnetostriction data. It became clear that electromagnetic vibration was affected by the magnetostriction of steel. These results will be useful in the reduction of acoustic noise and the development of quiet motors. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 8–13, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10338     

手机快速充电系统设计

设计了一种基于单片机STC89C52的手机快速充电系统,详细介绍了此快速充电系统的硬件设计方法和软件设计流程。使用这种快速充电系统,充电速度比普通的USB充电快50%以上,能提高智能手机的续航能力。同时,本快速充电系统做了兼容设计,可兼容普通充电功能。     

手机GCF一致性测试

GCF(global certification forum)一致性测试十分必要。GCF一致性测试包括射频、音频、协议、SIM、杂散五大类测试项。本文全面综述这五类测试的具体内容以及测试过程中所使用的测试系统,并介绍国际和国内从事GCF一致性测试的认证实验室,便于手机研发人员对GCF一致性测试有个全面的了解,清楚知道如何准备GCF一致性测试,以及在测试过程中如何进行调试。     

七频段金属外壳手机天线的设计

提出了一种应用在金属外壳手机终端上,实现了-6dB以下的带宽为800~960 MHz,1 710~3 000 MHz频段的天线设计。为了保证辐射性能和所需带宽,在金属的手机外壳的短边上开宽为2mm的U型槽,在馈电处采用电容匹配和一个可切换的电路接地枝节实现GSM850/900 (824~960 MHz),DCS/PCS/UMTS2100(1 710~2 170 MHz),LTE2300/2500 (2 300~2700 MHz)七个频段的覆盖。手机尺寸为152 mm×72 mm×6.8 mm,天线的净空区域为7 mm×70 mm。通过实物测试,手机天线的辐射效率,在低频824~960 MHz频段中为38%~46%,在1 710~2 700 MHz中,辐射效率为可达38%~64%。该天线具有很好的辐射性能,适合应用于金属外壳的移动终端中。     

能量回馈型超声波电机定子振动特性有限元分析与特性测试

提出一种集精密驱动和振动能量采集于一体的新型多功能压电振动电机——能量回馈型超声波电机,设计了电机夹心式内锥面压电定子,建立了电机压电定子的有限元模型,仿真分析定子振动特性和能量采集输出特性;研制电机原理样机,并对电机进行阻抗和能量采集特性测试与分析。研究结果为工作在极端封闭环境中的微型机器人系统提供一种集驱动与供电一体化的机电器件。     

Causes and characteristics of the electromagnetic vibration of a squirrel cage induction motor under load

Three-phase squirrel cage induction motors (IM) have been used in all types of industry, because of their robustness and simplicity of structure, low cost, and ease of maintenance. Due to the resultant air gap flux wave, an IM produces electromagnetic vibration and noise more or less regardless of the slot combination. Recently, reduction of electromagnetic vibration and noise has become important from the standpoint of environmental improvement. Vibration caused by an IM at no-load has been studied for many years and its basic factors have been analyzed. However, electromagnetic vibration under load has not been analyzed sufficiently. Since vibration under load conditions is affected by load and installation, analysis of this vibration is a rather difficult task. But study of the electromagnetic vibration of the motor itself under load is basically the most important item. This paper clarifies, theoretically and experimentally, the causes and characteristics of the electromagnetic vibration of an IM under load conditions. First, general equations are derived for the dominant electromagnetic force waves that produce electromagnetic vibration. Causes and vibration modes are clearly classified and a theoretical analysis provides a basic concept for electromagnetic vibrations. Second, electromagnetic vibrations for various loads are measured taking the effect of natural frequency of the motor into consideration. The measured data are classified and analyzed in detail, based on the proposed theory. © Scripta Technica, Inc. Electr Eng Jpn, 120(4): 81–89, 1997     

Analytical solution on the non-linear vibration of a traveling wave ultrasonic motor

A vibration model for the stator of traveling wave type ultrasonic motors has been presented using Kirchhoff plate theory. In this model, the vibration equation influenced by electric field is established based on the geometric equations, the constitutive equations and the balanced equations for the structure. This electric field distribution is assumed based on Maxwell equation. Shearing deformation, rotary inertia and damping of the piezoelectric ceramic are been taken into account. Firstly, the dynamics of the stator is discussed. The mode of the stator is derived and validated by comparing the resonant frequencies and modal shapes with those by finite element analysis. Then, the effect of the piezoelectric ceramic damping is also discussed. Finally, The friction layer is simplified as the axial spring. Using modal shapes as the weight function, the analytic solution under the forced vibration for the stator is computed by Galerkin method. The theoretical model and its analytic solution in this paper contribute to simplifying the model for the parametric study and understanding the vibration between the stator and the rotor.     

影响移动电话电池性能的关键因素

目前国内移动电话电池质量普遍较差。由于移动电话电池产品要与原装手机及充电器配套使用,因此必须对电池生产过程中影响其性能的关键因素加以控制,使其不仅性能可靠而且适用。通过笔者在生产实践中的研究和摸索,结合邮电部行业标准对移动电话电池的技术要求和试验方法,总结出影响移动电话电池性能的关键因素,包括：单体电池分选、保护电路的选择、成品检验等。通过对比实验介绍了单体电池分选的必要性,给出过流保护及热敏电阻选择所应考虑的参数范围,通过手机工作过程实例介绍了成品检测的必要性     

虚拟仪器在电机振动分析测控系统中的应用

介绍了基于虚拟仪器技术所构建的电机振动分析测控平台。该测控平台主要由数据采集模块、振动频谱分析模块、控制模块等部分构成。数据采集模块能够实时采集电机运行过程中的振动信号;通过振动频谱分析模块可对所采集的电机振动数据进行功率谱分析、谐波分析、STFT时频谱图分析等;测控平台中的控制模块可调用不同的控制算法,为电机在不同控制律下的振动情况研究提供了方便。测试实验结果表明,该测控平台可以有效地实现电机调速控制、振动数据采集与分析。