换相

Commutated reactance is an important parameter in HVDC transmission system.

换相电抗是高压直流输电系统中的一项重要技术参数。

The Routh criterion of control system theory is applied to obtain the stability criterion.

通过对整流桥换相过程的分析，建立了系统在稳态运行点的微变稳定模型。

According to the definition and the distribution of VSR's voltage space vector, the introduction of a rule-based SVPWM current control strategy, with non-fixed switching frequency and dual hysteresis loops, that obviously improves the performance of current control. Based on two kinds of control strategies of VSR under unbalanced grid condition, the introduction of a new VSR control strategy featuring undamped-oscillation that simplifies the controller structure and effectively improves VSR's performance under unbalanced grid condition. A systematic description of the state switching in trilogic PWM signal generation of threephase CSR by using the conversion between bilogic and trilogic switching functions.

作者在如下工作的基础上对PWM整流器的一些关键问题提出了自己的研究思路、观点和方法：根据PWM整流器网侧矢量关系，直观地描述了其四象限运行的基本原理及特征；定量分析了VSR、CSR的PWM换相过程及波形特征；引入等效变压器模型并详细分析了VSR、CSR基于d—q模型的动、静态特性；提出了满足四象限有功、无功运行指标时的VSR交流侧电感设计方法；并提出了依据控制系统跟随性和抗扰性性能指标设计VSR、CSR直流侧储能元件的参数计算方法；在研究了VSR电流控制策略基础上，提出了影响VSR电流控制的几个要素，并进行了定量分析；根据VSR空间电压矢量的定义及分布，提出了基于规则控制的不定频滞环空间矢量PWM电流控制策略，并由此提出了具有双滞环特性的不定频滞环优化SVPWM电流控制策略，有效地改进了滞环PWM电流控制性能。

Based on two kinds of control strategies of VSR under unbalanced grid condition,the introduction of a new VSR control strategy featuring undamped -oscillation that simplifies the controller structure and effectively improves VSR"s performance under unbalanced grid condition.· A systematic description of the state switching in trilogic PWM signal generation of three-phase CSR by using the conversion between bilogic and trilogic switching functions.· Referenced to the CSR"s trilogic PWM signal generation, an approach to achieve low-stress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss.

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；·通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；·结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

Referenced to the CSR's trilogic PWM signal generation, an approach to achieve lowstress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss. With the background of and well instanced by the Xinjiang Autonomous Region's Key SciTech Project"Solar Photovoltaic grid-connected inverter", the dissertation work implemented the new approach of a grid-connected PV inverter that was of single-phase VSR topology and with MPPT .

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

In this strategy, different start-up commutating instant under different source voltages are collected first.

该方法首先通过改变母线电压值，采集相应的起动换相时刻数据样本。

The method conquers overvoltage of commutation and inrush current of transformer when the breaker is closed.

该方法能够克服在换相过程中极易产生的过电压和合闸涌流对牵引变压器的冲击。

In the motor drive controller, current sampling cir- cuit protecting circuit, pressure adjusting circuit and signal insulating circuit are made up of DSP and its peripheral circuit. CPLD is employed to deal with the brushless DC motor＂ s rotor position signal in order to realize.

电机驱动控制器采用微控制芯片和外围电路构成了电流采样、过流保护、压力调节等电路，利用CPLD实现无刷直流电机的转子位置信号的逻辑换相。

To shorten the design period of control system of a satellite attitude control flywheel,and to verify the feasibility and effectiveness of design schemes,a control model based on a mathematics model for flywheels was established combined with acceleration techniques,reversal connection braking control and commutation control for the control system of flywheels.

为了缩短姿控飞轮控制系统的设计周期和快速验证设计方案的可行性及有效性，在分析姿控飞轮电机本体数学模型的基础上，结合该姿控飞轮控制系统所采用的加速控制、制动控制、换相控制，建立了姿控飞轮控制系统模型。

In this paper, MATLAB, through the Radon transform detection of a license point of view, rotation and shear transforms the use of a combination of solutions to correct the deformation of the license issue by color region extraction license to eliminate the interference color of the non-license, to solve complex license text area Extraction of the problem.

本文运用MATLAB，通过Radon 变换检测牌照的角度，使用旋转与错切变换相结合的方法来解决变形牌照矫正问题；通过对牌照区域进行颜色提取从而消除非牌照颜色的干扰，解决复杂牌照的文字区域提取问题。

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。