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The article presents the developing condition of PWM and SVPWM first.Then the theory of SVPWM is discussed in detail.The SVPWM is based on the thought of magnetic chain tracking.It makes the ideal magnetic chain circle of three-phased sysmmetry electric motor supplied by three-phased sysmmetry sine wave voltage for basis,uses the practical magnetic chain vector formed by the different switch modes of three-phased inverter to track the basic magnetic chain circle.During the course of tracking,the inverter changes the switch modes properly to form the PWM waves.Then the modulation wave of SVPWM is analyzed in detail.The modulation wave of SVPWM is implicit,but the analogous modulation wave in A-B-C axis needs to be calculated in order to expose the internal relation of SVPWM and SPWM.That is to show the implicit modulation wave of SVPWM. SVPWM actually is a transformed SPWM ruly sampled by the modulation wave which is injected by the zero prefaces based on space vectors.

本文首先对脉宽调制技术的发展现状进行了综述，在此基础上分析了电压空间矢量脉宽调制技术的发展现状；接着对空间电压矢量脉宽调制技术的基本原理进行了详细的分析和推导，SVPWM是基于磁链追踪的思想，它以三相对称正弦波电压供电下三相对称电动机定子理想磁链圆为基准，由三相逆变器不同开关模式下所形成的实际磁链矢量来追踪基准磁链圆的，在追踪的过程中，逆变器的开关模式作适当的切换，从而形成PWM波；然后详细分析了电压空间矢量脉宽调制技术的调制波，虽然SVPWM法的调制波是隐含的，但是为了揭示SVPWM法与SPWM法的内在联系，需要求出SVPWM在A-B-C坐标系上的等效调制波，也就是将SVPWM的隐含调制波显化；SVPWM实质是一种基于空间矢量在三相正弦波中注入了零序分量的调制波进行规则采样的一种变形SPWM。

The tea leaves on the plate, so that the role of tea in the rotation under the force, according to color, size, weight, thickness, whole pieces to form a hierarchical order.

将茶叶放在盘中，使茶叶在旋转力的作用下，依形状大小、轻重、粗细、整碎形成有次序的分层。

In this study, alkanethiolate molecules with -CH3 terminated tail group chemically adsorb upon Au substrate and form Au-S bonds, which potentially act as ultra-thin resist films with excellent uniformity in molecular order and high resistivity to chemicals.

且因CH3 官能基表面具化学惰性，针对特定化学蚀刻液拥有抵抗化学腐蚀之能力，以此特性将可应用於制作微奈米等级图案的超薄蚀刻阻剂。

In order to solve these problems, we design a new steam turbine jack pump oil supply system and supply in integrated form.

为了解决这些问题，我公司设计出了一套新型的汽轮机顶轴油供油系统，并以集成式方式供货。

In the case of planetary formation, the gravitational interactions between the dust in the disk, the mass in the larger aggregates of material, and the sun itself plus the friction of the material, its thermal properties, and the interaction between the magnetic fields from the star and those of the disk material itself plus countless other factors may be vital in order to understand how planets like our own form from the primordial disk of stardust.

在行星形成的研究中，碟状星尘之间重力的互动、较大聚集物的质量、太阳本身与这些物质间的摩擦、物质间本身的摩擦、物质本身的热力性质、太阳磁力场中这些物质的互动及磁力的影响，加上其他的无数因子都可能是了解地球如何从星尘中诞生的关键。

In order to improve the planeness and use value of cement concrete pavement and guarantee the high density and planeness of bridge floor like pavement,the article expounds the covering technology which uses slip form spreading machine to connect bridge floor with pavement.

针对提高水泥混凝土路面平整度和使用价值，保证桥面同路面一样具有高密实度、高平整度，为此论述了利用滑模摊铺机将桥面同路面连续一体铺装的施工技术。

Blowing song playing is the main form of play in order to play the main Qupai.

吹奏是吹歌演奏中最主要的形式，以吹奏曲牌为主。

In the times that regards transmission as medium with armour bone, hide, bamboo slip, cloth and silk, essential unthinkable mankind can use our ancestor the method such as reader of the computer, mobile phone, electron, enjoy reading fun in order to digitlize the form of encode.

在以甲骨、兽皮、竹简、布帛作为传播介质的时代，我们的祖先根本无法想象人类能够利用计算机、手机、电子阅读器等手段，以数字化编码的形式享受阅读的乐趣。

We need to have a sense of hope in either form in order to survive but it is important that we know the difference between the two.

所以为了生存，我们必须了解对待希望的这两种不同方式，但更重要的是了解这两种方式之间的差别。

Designers often draw on the structural nature of things to solve the problem or simply to form a sense of their order.

设计师们经常借鉴自然中事物的结构来解决问题或仅仅来形成他们的秩序感。

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。