带旁路电感的变压器耦合三相桥式固态限流器的控制策略研究

围绕新型变压器耦合三相桥式固态限流器试验样机工程化过程中的几个问题,提出该限流器的改进拓扑--带旁路电感的变压器耦合三相桥式固态限流器.给出了一种符合带旁路电感的变压器耦合三相桥式固态限流器特点的控制策略,并作了仿真研究分析.     

带旁路电感的变压器耦合三相桥式固态限流器的控制策略研究

围绕新型变压器耦合三相桥式固态限流器试验样机工程化过程中的几个问题,提出该限流器的改进拓扑——带旁路电感的变压器耦合三相桥式固态限流器。给出了一种符合带旁路电感的变压器耦合三相桥式固态限流器特点的控制策略,并作了仿真研究分析。     

高压断路器中直流电磁铁设计的讨论

本文讨论主压断路器中直流电磁铁的设计问题。提出了这类电磁铁的主要参数是输出的机械功,并得到影响静态机械功、动态机械功和工作效率的一些因素。     

高压断路器中直流电磁铁设计的讨论

本文讨论高压断路器中直流电磁铁的设计问题。提出这类电磁铁的主要参数是输出的机械功,并得到影响静态机械功、动态机械功和工作效率的一些因素。     

湛江电厂高压直流电除尘系统及安装介绍

本文重点介绍湛江３００ＭＷ火电机组高压直流电除尘系统的结构特点及我们在现场的实际安装经验。     

大型直流电机采用少胶粉云母箔卷包绝缘结构及效益分析

本文通过大型直流电机全部采用单面玻璃布补强少胶粉云母箔卷包的绝缘结构(简称全粉卷包结构)与我厂目前大型直流电机常用的多胶粉云母带,簿膜混合绕包绝缘结构的对比分析,说明全粉卷包结构具有良好的电气性能、经济效益和社会效益.     

Control and performance of a zero‐current‐switched,three‐phase PWM inverter equipped with resonant circuits on the ac side

This paper presents a zero‐current‐switched voltage‐fed inverter equipped with resonant circuits on the ac side. The current flowing through a switching device, that is, IGBT, is the sum of the load current and the resonant current. When the amplitude of the resonant current is larger than that of the load current, the current in the switching device becomes zero at an instant in each resonant cycle. This allows the switching device to be turned on or off at the zero current. The zero‐current switching makes a significant contribution to reduction of switching losses and electromagnetic noises. In this paper, the principle of zero‐current‐switching operation, along with a novel control scheme, is described from a theoretical and practical point of view. Experimental results obtained from a laboratory system of 5 kVA verify the practicability. Moreover, the switching and conduction losses of the proposed soft‐switched inverter are compared with those of a conventional hard‐switched inverter. © 2000 Scripta Technica, Electr Eng Jpn, 131(4): 85–95, 2000     

Discussion, with reply, of `A split-wound induction motor design toimprove the reliability of PWM inverter drives' by J.C. Salmon and B.W.Williams

With regard to the above-titled paper by J.C. Salmon and B.W. Williams (see ibid., vol.26, no.1, pt.1, p.143-50, 1990), the discusser points out that inverter drives featuring split-wound motors were marketed in 1971 by William Lear Enterprises, Inc. In reply, Salmon takes this opportunity to clarify some features of the inverter drive presented in his original paper. These features result in performance improvements over the standard unipolar inverter drive and the Lear inverter drive     

直流系统合闸母线运行方式对蓄电池组的影响及对策

对于直流负载存在大容量电磁式合闸机构的变电站,合闸母线的运行方式将直接影响蓄电池组的充电效果,本文通过建立变电站直流系统的等效电路,分析电磁式合闸机构开关在合闸操作过程中不同阶段对蓄电池充电的影响,提出了解决问题的方法,并结合现场有关实测数据进行验证。     

直流电压下湿度对某些典型外绝缘放电电压影响的试验研究

本文给出了支柱绝缘子、悬式绝缘子串、棒—棒间隙和棒—板间隙,在大气环境条件下,当湿度在3.5—22g/m~3变化时的直流放电特性。试验电压最为高900kV。由这些实验结果而得出的结论,对制定有关试验标准和HVDC工程设计人员都是有用的。     

Foreign Language Requirement for the Ph.D. in Electrical Engineering: A Survey of U. S. and Canadian Policy

Over the past decade approximately one-half of all institutions offering the Ph.D. in Electrical Engineering in the U.S. and Canada have dropped the mandatory requirement for translation skills. This correspondence attempts to reveal the nature and extent of this trend.     

Folly in Trade and Technology Policy (Comments on `Do we need atechnology policy?' by S.J. Kline and D.E. Kash)

The commenters note that S.J. Kline and D.E. Kash (ibid., vol.11, p.18-25, Summer 1992) raise a number of interesting points in their discussion of the functions of government technology policy. The commenters point out that the importance of the issues discussed by Kline and Kash is underscored by a recent tariff imposed on active-matrix liquid-crystal displays (AMLCDs). They suggest that it is important that the Kline and Kash article serve as the basis of continuing discussions within the IEEE community and other scientific and engineering communities, relative to issues of technology policy development. They conclude that perhaps the concerns expressed by Kline and Kash, and by N.W. Buckly (1992), will generate an increased level of understanding, concern, and discourse on this extremely important topic     

The Effect of Regulatory Reform on Employment and Earnings in the U.S. Electricity Sector

An analysis shows that employment decline sharply and also suggests that while earnings show little change due to regulatory reform, there is significant evidence that reform has been associated with a decrease in the probability of industry employment in some occupations.     

云浮发电厂1号炉蒸汽温度偏低和结焦问题的解决

针对云浮发电厂１ 号炉（４２０ ｔ／ｈ） 过热蒸汽和再热蒸汽温度偏低、燃烧不稳、结焦频繁等问题, 通过分析, 提出切实可行的改造方案： 合理布置卫燃带, 提高火焰中心高度, 改造燃烧器。改造实施后, 解决了１号锅炉在投产以来过热蒸汽和再热蒸汽温度长期偏低、结焦严重、机组达不到铭牌出力的问题。     

36槽2／8极交流电机变极绕组完全可选方案的研究

对36槽2/8极交流电机变极绕组进行详细研究,得到全部6个可选方案。这些方案的基波相带宽度从60°/160°过渡到150°/60°,基波绕组系数从0.8984/0.7199过渡到0.6353/0.8312。这些方案可供工程技术人员在选择变极绕组时参考。     

交流电机绕组理论中双极对槽号相位图的概念,画法和性质

本文提出了双极对单元电机——同时对两种极对数构成一完整电机时槽数最少的电机的概念;研究了交流电机绕组理论中双极对槽号相位图的性质,得出槽号不重复定理和糟号重叠定理,并指出双极对槽号相位图具有圆环胎面性质;除此,还提出了双极对槽号相位图的机器作图法。