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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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CHAPTER 1<br />

INTRODUCTION AND LITERATURE REVIEW<br />

1.1 Introduction<br />

The idea <strong>of</strong> using <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>machines</strong> c<strong>an</strong> be found in some papers<br />

published as early as the beginning <strong>of</strong> 20th century. However, high perform<strong>an</strong>ce control<br />

<strong>of</strong> the <strong>machines</strong> was difficult. Reasons included the absence <strong>of</strong> power electronic<br />

converters <strong>an</strong>d the incomplete <strong>an</strong>alysis <strong>of</strong> the <strong>machines</strong> due to the immaturity <strong>of</strong> machine<br />

theory, numerical simulation <strong>an</strong>d <strong>an</strong>alytical methodologies. Recently, <strong>dual</strong>-<strong>winding</strong><br />

<strong>machines</strong> <strong>of</strong> various types are being considered for various motor <strong>an</strong>d generating<br />

applications since two <strong>stator</strong> <strong>winding</strong> sets <strong>of</strong>fer the possibility <strong>of</strong> more flexible energy<br />

conversion. For example, energy c<strong>an</strong> be tr<strong>an</strong>sferred not only between <strong>stator</strong> <strong>an</strong>d rotor like<br />

what is found in single <strong>winding</strong> <strong>machines</strong>, but also indirectly between <strong>stator</strong> <strong>winding</strong> sets.<br />

Generally speaking, <strong>dual</strong> <strong>winding</strong> <strong>machines</strong> c<strong>an</strong> be divided into the following<br />

categories. The first is the oldest <strong>machines</strong> in the machine history <strong>an</strong>d it is always called a<br />

wound rotor <strong>induction</strong> machine. In this type, the rotor <strong>winding</strong> is always called the<br />

secondary <strong>winding</strong>, <strong>an</strong>d both the <strong>stator</strong> <strong>an</strong>d rotor <strong>winding</strong>s have the same number <strong>of</strong> poles<br />

<strong>an</strong>d number <strong>of</strong> phases. The most signific<strong>an</strong>t adv<strong>an</strong>tages <strong>of</strong> this machine lie in its ability to<br />

achieve a const<strong>an</strong>t output frequency at variable rotor speeds. This is useful in wind power<br />

generation. The ability to send the rotor slip energy back to the system improves the<br />

efficiency <strong>of</strong> the whole system.<br />

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