加热磁力搅拌器的结构及使用性能评析

加热磁力搅拌器，早期产品的电机多为交流电机，加热为分档加热．近期的产品多为微型直流电机，加热为控温加热．就加热元件而言，它们共同的缺点是热效率低，加热时间长．就驱动电机的使用寿命而言，交流电机大大长于微型直流电机；就加热方式而言，“控温”优于“分档”．由于“搅拌”是该设备的主要功能，因此不难看出，近期的产品反而不如早期的产品。     

功率因数监测与补偿教学系统的设计

功率因数监测与补偿教学系统以C8051F020高集成智能型单片机为控制核心,实现对电压、电流、频率、有功功率、无功功率、功率因数的检测以及完成对功率因数自动补偿控制。系统采用模块化设计,设计中运用交流采样技术对交流电压、电流信号直接采样以确保精度,用高精度的真有效值转换芯片AD637对取样信号进行转换,采用电平移位采集电流峰值测量瞬态电流,采用在电路中增减并入电容的方法进行功率因数的自动调节,提高功率因数。     

低压电动机无功就地补偿

低压电动机无功就地补偿,把无功电流局限在用电设备上,减少了电力无功在高、低压配电网上的流动,减少了线路损失,提高了电源设备的利用率,在补偿技术上最彻底,是一项节约用电,缓解电力供求紧张矛盾的有效措施。     

基于晶闸管的带泵控制功能异步电机软起动的仿真研究

为了减小异步电机在起动过程中过高电流对电网的冲击,消除传统降压起动对电气和机械设备的不利影响,提高电机的起动特性,本文对电机的软起动进行了研究,并对其进行改进,得出新型具有泵控制功能的软起动器,它不但具有一般软起动器的电压斜坡起动和限电流起动功能,而且其泵控制功能够降低水泵起动和停止时造成的水锤,减轻管路系统的振动,使软起动器的功能更加完善。文中利用MATLAB搭建三相交流调压电路系统的仿真模型,并且对所设计的软起动器进行了试验测试,仿真结果表明这种带泵控制功能的软起动器不仅可以有效地减小电机起动时对电网的冲击,还能够减轻水锤的冲击,优化了电机的起动性能。     

起重机的变频调速系统研究

讨论了起重机的电气传动特性和交流异步电动机的变频调速机械特性,交流异步电动机的变频调速机械特性在任何情况下都可以适应起重机的各种机构的电气传动特性,所以变频调速已成为交流异步电机的主要调速方式和发展方向．使用变频器变频调速可以使起重机的工作效率、平稳性、调速范围等性能大大改善．     

一种实用的三相异步电动机缺相保护电路

缺相是三相异步电动机负载运行时常见的故障之一,因缺相运行而造成的电动机烧毁事故在生产中占70％．传统的热继电器缺相保护存在反应慢、误动作或不能及时切断电路等问题．对传统的热继电器保护电路进行了改进,通过加接接触器,有效地实现了三相异步电动机的缺相保护．     

Design of an ultrasonic motor with multi-vibrators

This paper presents and verifies a new idea for constructing an ultrasonic motor (USM). The stator contains several vibrators fabricated by bonding piezoelectric ceramics (PZTs) to a metal base. When two alternating current (AC) voltages with a 90° phase difference are applied to the PZTs, longitudinal and bending modes are excited in the vibrator. The bending vibrations of the vibrators are stacked to form the torsional vibration of the stator, ultimately generating longitudinal-torsional composite vibration. Both vibrators and the stator are excited to the resonance state. A standing wave is formed by superposition of longitudinal and torsional modes. The proposed motor is an in-plane vibration motor because the vibrations of the stator are in the circumferential plane. The finite element method (FEM) is used to validate the feasibility of the proposed motor. The fabricated stator contains five vibrators. The tested resonance frequencies of longitudinal and torsional modes are 44.42 kHz and 43.83 kHz, respectively. The stall torque is 0.3 N·m and no-load speed is 45 r/min. The highest efficiency is 30%. The applied driving voltage is 100 V_o-p (peak voltage) at 43.9 kHz. The designed motor is a parallel-actuated integral motor. It allows the vibrators to operate synchronously, and overcomes asynchronous issues that occur in traditional multi-vibrator motors.     

正弦激励非零状态下的二阶电路暂态过程的研究

对正弦激励非零状态下的PLC串二阶电路的暂态过程进行了研究，给出了电路在接通正弦电源后直接进入稳态响应的条件，分析了暂态过程中出现的过电压、过电流现象。     

Exposure to intimate partner violence and internalizing symptoms: The moderating effects of positive relationships with pets and animal cruelty exposure

BackgroundIt is estimated that more than half of children living in households where intimate partner violence (IPV) occurs are also exposed to animal cruelty (AC). Although prior research links bonds with pets with higher levels of socioemotional competence among school-age children, exposure to AC may negate the protective effects of pet ownership and/or exacerbate the potentially deleterious effect of IPV on children’s mental health.ObjectiveThe current study evaluates whether and to what extent the associations between exposure to IPV and several indicators of children’s mental health vary as a function of children’s positive engagement with pets and exposure to AC.Participants and SettingParticipants included 204 children (aged 7–12 years; 47% female; 57% Latinx) and their maternal caregiver who were recruited from domestic violence agencies in a western U.S. state.MethodMultiple moderation analysis evaluated whether the association between children’s exposure to IPV and internalizing and posttraumatic stress symptoms vary as a function of children’s positive engagement with pets and exposure to AC.ResultsAnalyses revealed several moderation effects for positive engagement with pets (e.g., internalizing problems: [b = −.15, t(195) = −2.66, p = .008]; posttraumatic stress symptoms: [b = −.13, t(195) = −2.24, p = .026]), whereas exposure to AC only moderated the association between IPV and anxious/depressed symptoms (b = .32, t(195) = −2.41, p = .017).ConclusionsThese findings highlight the potential protective effects of positive engagement with pets and importance of screening for exposure to AC when engaging in trauma-informed work with children exposed to IPV.     

From psychomotor to ‘motorpsycho’: learning through gestures with body sensory technologies

As information and communication technology continues to evolve, body sensory technologies, like the Microsoft Kinect, provide learning designers new approaches to facilitating learning in an innovative way. With the advent of body sensory technology like the Kinect, it is important to use motor activities for learning in good and effective ways. In this article, we aim to examine both empirical illustrations and theoretical underpinnings for the gesture-based or motor-based learning enabled by the body sensory technology. We review and distill salient concepts and ideas from the existing theoretical and empirical literature related to body-movement- and gesture-based learning, and propose a motorpsycho learning approach. In our discussion, the word/affix motor is synonym to gestures and body movements, and psycho is synonym to cognitive activities. We explore the important role that motors play in psychological activities, especially in cognitive learning. We argue that motors can facilitate psychological activities in learning by enhancing information processing, encoding, representing, and communicating. We also call for more empirical studies on technology-enhanced and gesture-based learning to design, practice, and examine the motorpsycho learning approach.     

直流电动机闭环调速系统的限流措施

在直流电动机闭环调速系统中,当直流电机突加电压或出现堵转时,电机的电枢电流很大,有时达到电机额定电流的20倍,对电机十分不利.利用普通的熔断器或过流继电器都不能解决问题,电流截止负反馈是解决这一问题的有效方法.     

新颖的正激式高频环节交-交变换器(英文)

提出新颖的正激式高频环节交交变换器电路结构和电路拓扑族 ,这类电路结构由输入周波变换器、高频变压器、输出周波变换器以及输入、输出滤波器构成 ,电路拓扑族包括全桥全波式等8种电路 .深入研究了这类变换器的双极性移相控制策略和稳态原理 ,获得了外特性曲线 .采用具有输出周波变换器与输入周波变换器之间移相、输出周波变换器换流重叠、输出滤波电感电流和输入电压极性选择的双极性移相控制策略 ,这类交交变换器的周波变换器上的尖峰电压和环流得到抑制 .这类变换器具有电路拓扑简洁、两级功率变换 (低频交流 /高频交流 /低频交流 )、双向功率流、高频电气隔离、输出波形质量好和稳压能力强等优点 ,为实现新型的正弦交流稳压器和电子变压器奠定了关键技术基础 .原理试验很好地证实了这类变换器的正确性和先进性 .     

一种补偿教学实验装置的设计与实现

硬件实验在计算机教学中的地位越来越受到重视,先进的教学实验装置将有效提高计算机实验教学的质量。我院控制实验课题组根据目前教学实验装置的研制开发指导思想,研制开发了一系列“计算机应用系列实验教学仪器”,其中新研制开发的一种功率因数自动补偿实验装置,使学生深入了解交流功率因数补偿的基本概念,掌握测量交流电压电流相位的方法,掌握电容补偿的方法。     

电压型逆变器主电路优化策略研究

逆变器可将直流电能变换为交流电能,可用于构成各种交流电源,在实际中得到广泛应用．现代工业的发展对逆变器的电压等级、设备容量和谐波含量等指标提出了更高的要求．分析了电压型逆变器主电路结构优化措施,并在MAT—LAB／Simulink中进行了仿真分析．仿真结果表明所采用的优化策略可使逆变器输出获得更高的电能质量、更低的谐波含量．     

非同步交流采样的测量与计算

对交流（AC）信号进行同步采样,如电网电压和有功功率均方根值,为了测量计算的非同步交流信号（在文10-6[1]的部分）。提出了一种估值测量的数学表达式,它可测量非同步基频交流信号。用该方法测量的结果与高精密仪器测量的结果进行了比较。最后通过仿真实验证实了此方法的有效性和实用性。     

工业电力用户无功功率收费问题的探讨

因为无功功率在用电设备运行中不做功,所以其收费问题一直没有引起人们重视．无功功率在电动机、变压器等用电设备运行时是不可或缺的一部分,它在电路内进行电场与磁场的能量交换,并用来在电气设备中建立和维持磁场．有电磁线圈的电气设备,要建立磁场,就要消耗无功功率．当电网无功功率不足时,电网的电压将降低;当电网无功功率过剩时,电网电压将上升,影响电网经济和安全运行．导致电网无功功率不足和过剩的主要问题是电力用户用电设备的无功补偿问题．随着电子电能表的发展,无功功率收费成为可能,这是合理解决用户用电设备无功补偿问题的有效手段．     

电机节能控制技术的设计与实现

异步电动机是工业用电的主要拖动设备,实现异步电机的节能控制将有效降低系统总体功耗。本文根据交流异步电机运行过程控制特点,提出基于最小电流的工作电压控制方式,实现电机的能耗控制。重点从软、硬件两个方面进行了探讨,设计了系统的硬件主控单元结构,并就系统的基本原理以及软件的实现思路进行了介绍。     

Optimization of total harmonic current distortion and torque pulsation reduction in high-power induction motors using genetic algorithms

This paper presents a powerful application of genetic algorithm （GA） for the minimization of the total harmonic current distortion （THCD） in high-power induction motors fed by voltage source inverters, based on an approximate harmonic model. That is, having defined a desired fundamental output voltage, optimal pulse patterns （switching angles） are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation （PWM） waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that if the pulsing-torques are at low frequencies, they can cause troublesome speed fluctuations, shaft fatigue, and unsatisfactory performance in the feedback control system, the 5th, 7th, 1 lth, and 13th current harmonics （in the case of five switching angles） are constrained at some pre-specified values, to mitigate the detrimental effects of low-frequency harmonics. At the same time, the THCD is optimized while the required fundamental output voltage is maintained.     

A novel control strategy for load converter of DC isolated distribution system under unbalanced loading conditions

A novel control strategy for the load converter supplying the unbalanced AC load in a DC isolated distribution system is presented. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in the d-q-0 rotating coordinate based on symmetrical sequence components. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is a newly proposed control strategy based on the decomposition of the voltage and current into in- stantaneous positive, negative, and zero sequences. These three sequences are controlled independently in their own reference frames as DC signals. The performance of the load converter using these two control strategies is compared. Simulation results show the validity and capability of the newly proposed control strategy.     

基于MSP430单片机的无线充电器设计

采用MSP430F2274超低功耗单片机作为无线传能充电器的监测控制核心,通过开关选择充电的速度,实现快速充电和常态充电功能,电能充满后给出充满提示且自动停止充电。能量发送端可用市电和直流电源供电,具有交流优先和交直流自动切换的功能,电压和充电时间显示采用低功耗OCM126864-9液晶屏。该设计系统具有无线充电、能量传输效果好、携带方便、成本低、无需布线等优势,有着广泛的应用前景。