An investigation of the quality of the output voltage,current, and energy relationships of independent inverters with transformers with a rotating magnetic field

It is analyzed how commutator circuits of independent inverters with transformers with rotating magnetic fields influence the quality of the output voltage and current. Based on a harmonic analysis of curve forms under different types of loads, the dependences of the coefficients of voltage and current harmonics on the number of power-key pairs involved in commutators of independent inverters with transformers with rotating magnetic fields have been determined.     

Influence of controlled rectifier with transformers of rotating magnetic field on the supply network

Based on a harmonic analysis of the feed voltages of controlled rectifiers with transformers with rotating magnetic fields under different types of loads, the relationships between the coefficients of feed voltage harmonic and the number of power-key pairs of rectifiers’ commutators with transformers of rotating magnetic fields were clarified.     

Output voltage quality of a rectifier designed on the basis of a transformer with rotating magnetic fields at even and odd number of circular winding sections

On the basis of a geometrical analogy between a circular winding and regular polygon, the dependences of the rectified voltage ripple factor on the number of sections of circular winding for rectifiers designed on the basis of transformers with rotating magnetic fields have been ascertained.     

电机换向器片间介电强度自动检测仪设计

介绍了一种交流串励电机换向器片间介电灶度自动偷测仪，采用步进电功饥驱动换向器转动，实现了检测停留时间的精确调节，同时还采用特殊的检测电路和机械结构，实现了检测电压的可调并充分考虑检测仪的可靠性和稳定性，以及对不同规格换向器适应性和操作的简易性。     

增安型无刷励磁同步电动机设计的几点改进

简要介绍了增安型无刷励磁同步电动机总体结构、励磁绕组、旋转整流盘和磁极铁心设计的改进，并简要介绍了相应工艺。     

Specific features of the development of differential-phase transformer protection systems on the basis of magnetic reed switches

It shown that the magnetic reed switches installed close to flexible current leads of power transformers with power over 6.3 (40) MV A and high voltage 10 (35) kV may be used as a basis of phase-comparison circuits with specified boundary angles in the devices for the protection of these transformers against short circuit. The response threshold of these circuits, the errors caused by the differences between the intrinsic response times, inaccuracies in settings of magnetic reed switches, and regulation of the transformer voltage are estimated. A technique for suppressing the effects of adjacent phases and electric installations is presented.     

特殊函数旋转变压器基本公式探讨

由谐波绕组构成的特殊函数旋转变转压器，必须考虑齿谐波和气隙磁场衰减的影响．本文分析了上述因素，并获得了这种电机的基本方程式，为进一步提高这种电机的精度提供了理论依据。     

直流电动机新论

作者在对新一代直流电动机(New DCM)的研究中发现并提出了直流旋转磁场这一电机学的新概念,是用换向控制器来控制电子换向器中功率开关管的导通状态及变化顺序,让通电直流电枢绕组磁势沿电枢表面圆周旋转而达到的。与交流旋转磁场一样,都是电枢绕组电路产生的磁势,它的旋转是由于电枢绕组线圈内电流瞬时值沿圆周分布变化引起的,与定转子机械相对运动没有关系。从转子的角度看电枢的旋转磁势是直流绕组电流还是交流绕组电流产生的并没有什么区别,所以对应不同的转子结构也能构成类似于交流同步电动机和交流异步电动机基本作用原理的电动机,又有所区别,出现了直流同步电动机和直流异步电动机的新概念和新名称。该文的研究有助于加深认识和开阔思路。     

Harmonic response tests on distribution circuit potentialtransformers

Experimental data are presented that show the performances of distribution circuit potential transformers operating with nonsinusoidal waveforms. Four standard magnetic voltage transformers designed for 60 Hz power applications and rated from 7.2 kV to 20 kV were tested. Ratio correction factor and phase angle measurements were conducted at rated 60 Hz voltage with harmonic distortion levels at and below 8%. Test results indicate that potential transformers rated up to 20 kV experience errors of less than 5% at harmonic frequencies up to 3500 Hz when operating into typical induction watthour meter burdens. The phase angle response is essentially linear over the frequency range used to test the transformers, with a typical phase angle of about -10° at frequencies of approximately 3 to 3.5 kHz     

选相关合技术抑制空载变压器励磁涌流的实验研究

针对随机关合空载变压器产生励磁涌流的问题,采用选相关合技术来抑制励磁涌流。在分析选相关合空载变压器原理的基础上,研究了同时合闸策略、快速合闸策略和延时合闸策略下铁芯磁通的变化规律,并对比分析三种合闸策略的适用条件。最后搭建选相投切10 kV空载变压器实验平台,对有无剩磁时不同关合相位下的励磁涌流进行分析。实验结果表明:变压器铁芯无剩磁时,在电压峰值处合闸可以有效抑制励磁涌流;铁芯存在剩磁时,在电压峰值处合闸仍会产生励磁涌流。因此,有必要预测铁芯剩磁以确定最佳合闸相位,实现空投变压器的无冲击平滑过渡。     

旋转电弧开关及其电弧运动速度特性

为满足脉冲功率技术对闭合开关高电压、大电流、高电荷转移量、电极烧蚀小、寿命长的要求,设计了一种轴向磁场控制的旋转电弧开关。利用有限元软件分析开关间隙中驱弧磁场的位形及大小,得到间隙中磁感应强度与开关结构参数及电流大小的关系。采用B-dot探针测量电弧的旋转速度。实验电源为时序放电回路,在开关上得到近似梯形状的电流波形,实验中电流为18～72 kA,磁感应强度为0.104～0.628 T。通过改变上下线圈的匝数,得到在不同驱弧磁场下电弧的运动速度,并与其他旋转电弧开关的运动速度进行比较。对实验数据进行拟合,可知电弧运动速度与间隙中的轴向磁感应强度大小成指数关系。该关系表明,所设计的开关中,电弧运动速度可以由间隙中的驱弧磁场惟一确定,这与外部磁场驱弧方式相比有很大的区别。     

温度对典型光学电压互感器误差特性影响的研究

光学电压互感器容易受到温度影响,其误差特性是实际工程应用关注的焦点。文中首先介绍了几种典型原理的光学电压互感器,建立了光学电压互感器试验平台及试验方案,并针对已经实用化的2种原理的光学电压互感器开展了温度影响试验,提出了电容分压原理的光学电压互感器温度性能较好的观点。     

逆变器并联控制技术研究

本文研究了无输出隔离变压器的逆变器并联系统环流特性及其并联控制实现。在确定双闭环控制逆变器闭环传递函数并了解其等效输出阻抗特性的基础上,建立了基于等效输出阻抗的并联系统模型分析其环流特性,并提出了一种新的基于有功功率和无功功率的逆变器并联控制方案,最后通过实验验证了逆变器并联控制方案的可行性。     

应用旋转热管调压调速电机的温度场计算

提出了一种应用旋转热管的调压调速电机在不同转速下温度场的计算方法。首先对电机在不同转差率下，电机电源的输入波形进行了分析，根据不同频率下电机等效电路及磁场的分析，得到了不同频率下损耗的计算方法；接着对旋转热管在不同转速下的传热性能进行了分析，建立了旋转热管传热过程的数字模型；并对传统的电机温度场计算方法－等效网络法做了改进，提出了一种简化的等效网络法。最后建立了具有旋转热管调压调速电机简化的等效网     

A compensation method of ripple voltage on DC tachogenerator

A dc tachogenerator has been used widely in such applications as computer peripherals and machine tools. However, this generator has some problems, e.g., the ripple voltage involved in the output voltage and the abrasion of the brush and the commutator. The ripple voltage of a general dc tachogenerator is from 1.5 to 5 percent of the output voltage. This voltage must be reduced to very small value in consideration of the influences on control systems. A compensation network of the ripple voltage on this generator was proposed in a previous paper. Here, the network is improved so as to operate effectively without losing the high response even when the rotating speed is changed slightly. The performance of the proposed network is discussed in detail, and the method for the design of the network to satisfy the requirements both of the ripple voltage and of the response time is proposed. The experimental results show that the ripple voltage is eliminated perfectly at the steady state, and that the high response is not lost.     

Control of the output voltage of a controlled rectifier based on a transformer with rotating magnetic field

A new control method for a rectifier based on a transformer with a rotating magnetic field (TRMF) containing an even number of sections of circular winding (CW), which makes it possible to double the number of ripples of rectified voltage in the supply-voltage period, is considered. It leads to a reduction in the ripple amplitude and improves the quality of rectified voltage. The geometrical similarity of the CW of a TRMF making it possible to implement the new control method is analyzed. Switching algorithms of power switches for the classical and new control methods for any quantity of an even number of CW sections are presented. As an example, a switching queue of power switches for a CW with ten sections is considered. The output-voltage shapes for different depths of control are shown. The calculating procedure of the control characteristic for the classical and new control methods, as well as corresponding diagrams, are presented. For the presented example with ten sections of CW, the efficiency of the new control method was evaluated and the dependences of the voltage-ripple ratio on the RMS of rectified voltage are presented. A comparative analysis of the number of ripples for different quantity of CW sections was conducted, and the harmonic composition of output voltage spectrum for the example under consideration is determined. It has been concluded that, in the case of using the new control method for achieving the desired quality of rectified voltage, the number of CW sections may be halved compared with the classical control method, which will simplify the manufacture of a transformer magnetic conductor, halve the number of pairs of power switches switching the CW taps, and decrease the mass, dimension, and cost factors of a semiconductor switch and the TRFM itself as a whole. Using the new control method makes it possible to make a controlled rectifier with an even number of sections of a CW transformer almost as efficient as using a transformer with an uneven number of CW sections and the classical control method. The new control method ensures the fulfillment of the requirements for the available value of the ripple ratio of the output voltage of a controlled rectifier based on a transformer with a rotating magnetic field set out by State Standard YuST 13109-97 at a lower RMS of rectified voltage.     

ANSYS软件在电压互感器设计中应用

运用有限元分析软件ANSYS建立了35 kV电磁式电压互感器的有限元分析模型,并对模型内部的电磁场分布情况进行了分析、计算.应用ANSYS有限元分析中的优化设计技术,对电压互感器的电磁结构(二次绕组匝数及一、二次绕组导线的截面积)进行优化,通过比较优化前后的结果,可以看出优化后电压互感器内部磁场分布更为合理,线圈中磁场的增强有助于进一步减小铁心的体积.     

可检测多台互感器的全自动互感器校验装置

介绍一种新型的自动化程度极高的互感器校验装置，可实现互感器的全自动检定、自动打耐压、自动测互感器变比、自动退磁和自动测量VA特性，最大的特点是可以接入多台互感器，将多台互感器的测试数据依次读出，操作简单，全部由计算机控制。     

葛—南直流输电工程无功及电压控制的研究

为解决葛南线运行中存在调压范围不足,无功补偿不够的问题,通过对两种控制方式下交、直流系统无功交换量的数值和换流变分接头动作频度及α变化幅度等技术指标的计算,分析比较了上述两种无功及电压控制方式各自的特点,指出了葛—南直流输电工程的缺陷,提出了无功控制及交流电压控制的具体改进建议。     

变压器的电力电子化演进及其对电压稳定影响综述

变压器作为电网中保持电压稳定性和改善电网电压质量的一种重要设备,一直是相关领域的研究热点。近年来随着电力电子技术的发展,由于电力电子器件相较于传统机械结构的高度可控性和不产生电弧的特性,变压器逐渐呈现电力电子化的趋势。首先将变压器按电力电子化发展方向的不同分为了两个阶段,并归纳总结了变压器电力电子化进程各个阶段的拓扑结构。在此基础上对每个电力电子化阶段的变压器对有载调压的影响做了详细介绍。最后对不同电力电子化阶段的变压器对电压稳定性的影响做了对比,对变压器的发展趋势和关键问题进行了总结与展望。