一种实用的电动机断相和错相保护装置

三相电动机断相和错相保护装置主要由三相同步检测电路、断相和相序逻辑鉴别电路及输出电路等环节组成.其保护逻辑方框图如图1所示. 将断相和错相保护装置的输出继电器的常闭触头串入电动机控制回路中,故障发生时,输出继电器动作,其常闭触头打开切断电动机控制回路,并点亮报警信号灯.     

挖掘机中的错相和缺相保护电路

本文从理论上分析了错相、缺相的判别原理,以及挖掘机上的实际应用电路,其线路简单、实用,同时给出了推广应用的方法。     

电网相序和缺相监测电路的设计

文章论述了电网相序变化的原因及其造成的影响，提供了实用的相序监督电路，分析了相序监测原理，适用于电设备及电动机的安全运行保护。     

一种新的鉴相倍频电路

介绍一种新的鉴相倍频电路ＰＤＣ９３０１，用它替代以前利用阻容件实现的鉴相倍频电路，使用效果良好。     

交流接触器的选相合闸电路

介绍一种简单易行且具有较高选相精度的选相合闸电路，并给出了应用此电路后，所获得的ＣＪ１０－１０型交流接触器在不同的合闸相位下，通电时吸合过程的线电压及电流波形图。     

三相异步电动机断相运行分析

应用三相对称分量法对三相异步电动机断相运行的电流,电压特性进行了分析,给出了三相异步电动机空怕相运行的矢量图,介绍了中性点电压取样电路及试验结果,为进一步设计电压取样型断相保护电路提供了理论依据。     

一种四相整流电路及其工作机理分析

为降低整流系统产生的谐波,提出了一种四相整流新概念,对四相整流的接线方式、工作原理及其特有的谐波特性进行了分析,研究了四相整流电路的相关量与触发角的变化关系,并与传统的三相整流电路进行了对比.建立了Matlab/Simulink四相整流电路分析的仿真模型并进行了详细的仿真实验.研究表明:四相整流系统直流侧只存在4的倍数次谐波;在相同输入电压条件下,四相整流电路的输出电压和输出功率远大于三相整流电路;在相同输出功率情况下,四相整流电路各晶闸管承受的反向电压较三相整流电路低.     

错相和缺相保护的探讨

1.前言 在交流电动机的自动控制系统中,我们常常碰到电源错相或缺相的情况,错相时将引起电动机反转,缺相时往往引起电动机烧坏等事故,目前国内对这种情况采取的主要措施是采用电子式缺相或错相保护电路,这类电路大多采用了较多的电子元件,结构比较复杂,价格较高,且工作可靠性较差,维护工作量较大。本文提出三种较为简单实用的控制线路,仅用继电器、附加电容和电阻,便构成了相序测量环节,且具有错相和缺相的保护控制功能。     

相控变流器的垂直移相电路

本文对相控变流器的垂直移相控制方式作了比较，认为正弦波垂直移相电路的控制特性优于锯齿波垂直移相电路。提出了三种正弦波垂直移相电路，并建议做成专用ＣＭＯＳ集成芯片。     

移相全桥高效DC-DC变换器研究

介绍一种移相全桥同步整流变换器的设计方法,阐述了移相全桥电路的工作机理及实现软开关的边界条件.该电路通过应用软开关及同步整流技术可获得较高的效率,具有很好的实用价值.     

Novel adaptation of the critical clearing angle formula for faults on a three phase and a six phase line

Enhanced power transfer through polyphase conversion of a transmission line, specially three to six phase, as an alternative to upgrading the conventional three phase power transmission voltage is becoming an area of growing interest in the power industry. Among others this conversion will have an impact on the system stability. While the well-known symmetrical component method has been found suitable in modelling the unsymmetrical faults of a three phase system for transient stability analysis it appeared as difficult-to-apply for six phase system. In this paper a new technique has been proposed to determine the stability in terms of critical clearing angles for both three and six phase line faults. The method has been validated by applying it first for the faults on a 132 kV three phase double circuit line of a given practical power system and comparing the results with those obtained through the symmetrical component method. Then it has been applied for the faults on the same line but considered to have been converted into a 132 kV six phase single circuit line. The method, though an approximate one, is straightforward, simpler and faster than the symmetrical component method and provides sufficiently accurate results.     

一种用于相移干涉仪的高压放大电路

基于自主研制高精度数字化相移干涉仪的需求,针对干涉仪的压电陶瓷移相器设计了一种高压放大电路。通过双极性运算放大器OP07构成低噪声,非斩波稳零的低压放大电路与中功率线性三极管MJE340和MJE350构成高压放大电路进行直流耦合,结合反馈网络,功率放大电路,滤波电路以及限流保护电路,将计算机输出的0~5 V低电压的移相控制信号稳定线性放大到-30 V~+130 V范围,且输出低至10 mV 峰值的纹波,满足压电陶瓷移相器的高压驱动控制要求和相移干涉仪的高精度移相测量的要求。     

一种新颖的节能装置用功率驱动及电流信号检测电路

针对当前三相异步电动机调压节能装置驱动电路复杂、电流过零点检测困难等问题,设计了一种三相异步电动机调压节能装置的功率驱动及电流过零点检测电路,阐述了其工作原理,通过实验对设计的合理性进行了验证.实验结果表明,该驱动电路运行稳定,电流过零点检测电路能够准确捕捉电流过零点的时刻.     

基于电流突变量曲线拟合的故障时刻检测算法

传统基于相电流突变量的故障时刻检测方法虽然简单,但因受暂态分量的影响而存在较大的检测误差。利用现有保护装置采集的电流信息,对相电流突变量进行曲线拟合,并经逆向推导求出故障时刻。对电力系统的短路暂态过程进行分析,探究相电流突变量的变化规律并推导其广义表达式。利用Prony算法对离散的相电流突变量值进行函数拟合,得到表征其函数曲线的特征参数;通过改进现有的波形相似算法,进一步从拟合函数的过零点中筛选出故障时刻。结合PSCAD仿真测试,探究故障时刻的检测精度及其影响因素,仿真结果验证了所提算法的可行性和准确性。     

电源控制器相地保护电路的独特设计

随着集成电路的飞速发展,短路保护电路变得越来越重要,特别是相地间的直接短路。介绍了一款投影机电源的相地短路保护,当出现短路现象时,该保护电路能够迅速切断电源,从而保护其他关键器件,比如电源管理芯片。使用一个电阻RSC检测相线L1中的电流,如果L1中电流超过了设定电流,该保护电路就会发挥作用,将IC PWM输出关闭。设定电流为额定输入电压时工作时电流的3倍,这等于给电气产品短路保护方面上了双保险。使用Pspice软件对设计电路进行了仿真,结果显示本设计达到了预定目的。     

A novel three‐phase converter using a three‐phase series chopper

This paper proposes a novel three‐phase converter using a three‐phase series chopper. The proposed circuit is composed of three switching devices, three‐phase diode bridge, input reactors, and LC low‐pass filter. In the conventional circuit, which combines three‐phase diode bridge and boost voltage chopper, to obtain sinusoidal input current the output voltage must be two or three times larger than the maximum input line voltage. However, in the proposed circuit, the input current can be controlled to be sinusoidal also when the output voltage is the same as the maximum input line voltage. This can be achieved because in the proposed circuit the discharging current of the reactors does not flow through the voltage source. The control method of the proposed circuit is as simple as that of the conventional circuit since all three switching devices are simultaneously turned on and off. This paper discusses the theoretical analysis and the design of the proposed circuit. In addition, simulation and experimental results are reported. The proposed circuit has obtained a 93% efficiency, and 99.7% at 1.3kW load as the input power factor. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 79–88, 2000     

两种单相电路谐波及无功电路实时检测方法的分析比较

针对有源电力滤波器(APF)对谐波及无功电流实时检测的要求,提出了两种单相电路谐波及无功电流检测算法,即基于瞬时无功功率理论检测法和基于基波幅值分离检测法.给出了两种算法的检测原理并分别对其进行了仿真研究,仿真结果表明后者算法动态响应快、检测精度高,是一种便于实现的实时检测算法.     

Capacitor current imbalance and its suppression method between phase legs for three‐phase inverter

This paper proposes a method to suppress the capacitor current imbalance between the phase legs of a three‐phase inverter circuit. This circuit consists of half‐bridge modules and DC‐link capacitors closely connected to each module. It can be designed for low stray inductance between power semiconductor devices and DC‐link capacitors in each module. However, in the conventional structure, the stray inductance between the phase legs may lead to an imbalance in the capacitor current due to the DC‐side resonance phenomenon under a higher switching frequency condition by using a SiC MOSFET. This paper presents the analyses of the equivalent circuit considering the circuit configuration, which suggests that capacitor current imbalance occurs depending on the stray inductance between phase legs. To suppress the capacitor current imbalance, a delta‐type bus bar connecting phase legs is proposed. The experiment results at 300 V and 4.6 A demonstrate the suppression effectiveness of the proposed method.     

单相自适应检测在三相无功及谐波电流检测中应用

电力有源滤波器作为一种有效的抑制谐波干扰的动态补偿装置,要求对无功电流、高次谐波电流、负序电流等补偿参考电流进行高精度的瞬时检测。根据传统有功功率的定义和自适应干扰对消原理,在仿真分析自适应检测电路的动态特性和检测精度关系的基础上,提出其一个改进的检测电路。改进的检测电路继承了自适应检测电路的优点,而且在保持一定的检测精度时具有更好的跟随性能。同时,在这种改进的单相检测电路基础上,按流入电源电流三相平衡原则,形成三相检测电路,它能适用于三相负荷不平衡时的检测。仿真结果表明了它的可行性。     

基于瞬时无功功率理论的串联混合型单相电力有源滤波器

本文介绍一种串联混合型单相电力有源滤波器。首先与无源滤波器及并联型有源滤波器对比，分析了其补偿原理和特点。随后，介绍了其主电路结构及各部分功能。在对三相电路瞬时无功功率理论的思想进行扩展的基础上，得到了单相电路谐波电流的瞬时检测方法。对实现这于检测方法的基于ＤＳＰ微处理器的数字控制电路的结构和工作过程也作了简要介绍。仿真和实验结果表明，该检测方法是有效的基于此检测方法的串联混合型单相电力有源滤波器