换相

This is referred to as trapezoidal commutation or block commutation.

这被称为梯形换相或阻塞换相。--不理解

The locomotive adopts chopper main circuit of 4 uncombined phases and a control mode featuring accessory pulse generated firstly, main pulse secondly, and central phase shifting of the 4 phases.

该车采用了4相不重的斩波主电路和先发副脉冲、后发主脉冲及4相集中移相的控制方式，并特别试制了适用于斩波的滤波电容器及换相电容器。

The Mixed pole-changing simplex winding multispeed motor can eliminate the imbanlance current in parallel branch circuits of parallel pole-changing windings, this is another significant breakthrough after " pole and amplitude modulation speed " in the pole-changing motor development history and is at the world leading position.

混相变极的单绕组多速电动机能消除并联换相变极绕组诸并联支路间不平衡环流，是变极电机发展史上继&极幅调速法&之后又一重大突破，处于世界领先地位。

Single-phase calculation method of commutated reactance is a traditional one.

换流变压器的换相电抗计算常采用单相测量法。

The capacitor commutated converter, that is CCC, can overcome the inherent drawbacks of conventional converters.

电容换相换流器能够很好地克服传统HVDC换流器存在的固有缺陷。

Taking the particularity of the connection scheme of novel converter transformer and its filter system into account, it's necessary to find out the relation between its commutated reactance and short-circuit impedances between windings and fundament frequency impedance of filter branch for impedance design of novel converter transformer and reactive power ...

考虑到新型换流变压器及其滤波系统的接线方案较为特殊，了解其换相电抗与绕组之间的短路阻抗及阀侧滤波支路的基频阻抗之间的关系，对新型换流变压器的阻抗设计和阀侧无功补偿度的优化配置是十分必要的。

Commutated reactance ; novel converter transformer ; impedance design ; reactive power compensation factor

换相电抗；新型换流变压器；阻抗设计；无功补偿度

Taking the development platform of HVDC power transmission for example, the calculation result of impedance-frequency characteristic of traditional line commutated converter and that of FCC are compared. Simulation results show that the impact of impedance-frequency characteristic of converter on the resonance frequency of AC system is not negligible, and FCC can enhance the strength of AC system in a certain extent, improve system stability and effectively reduce AC equivalent impedance under resonance frequency, thus the harmonic instability of HVDC power transmission system can be avoided.

以直流输电开发平台为例，对传统电网换相换流器(line commutated converter，LCC)与FCC的阻抗频率特性计算结果进行对比，仿真结果表明换流器的阻抗频率特性对交流系统的谐振频率有着不可忽略的作用，FCC在一定程度上提高了交流系统强度，改善了系统稳定性，有效降低了系统谐振频率下的交流等值阻抗，从而更好避免直流输电系统谐波不稳定现象的发生。

The torque ripple was large when its speed was low,its application was limited for the commutating process.

摘 要：常规永磁无刷直流电机，其换相位置检测采用霍尔开关元件，由于换相过程的存在，其低速运行时转矩脉动较大，限制了其应用。

DC power transmission simulationmodel is set up in this paper with the Matlab software, and various faults such as single-phasegrounding short circuit, phase to phase short circuit, three-phase circuit grounding shortcircuit and inverter bridge short circuit are simulated in this model.

用MATLAB软件建立了电力系统直流输电仿真模型，模拟了单相接地短路故障、相间短路故障、换流器桥臂以及单桥故障，经过近百次仿真运行，得出了各种故障下的特性曲线，准确描述了直流输电系统在发生大扰动后的暂态过程，并从理论上进行了科学分析，得出了各种故障对换相失败的影响。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。