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an investigation of dual stator winding induction machines

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CHAPTER 4<br />

FULL MODEL SIMULATION OF DUAL STATOR<br />

WINDING INDUCTION MACHINE UNDER ROTOR<br />

ECCENTRICITY CONDITIONS<br />

4.1 Introduction<br />

Induction <strong>machines</strong> have small air gap lengths to enh<strong>an</strong>ce their energy tr<strong>an</strong>sfer<br />

capability. Air gap eccentricities c<strong>an</strong> greatly influence machine perform<strong>an</strong>ce. The rotor<br />

eccentricities are classified into three categories: static eccentricity, dynamic eccentricity<br />

<strong>an</strong>d mixed eccentricity. The diagrams <strong>of</strong> different rotor eccentricities <strong>an</strong>d previous work<br />

reviews have been given in Section 1.2.3. However, the eccentricity <strong>an</strong>alysis <strong>of</strong> <strong>dual</strong><br />

<strong>stator</strong> <strong>winding</strong> <strong>induction</strong> <strong>machines</strong> has not been investigated.<br />

This chapter considers the effect <strong>of</strong> rotor eccentricities in the perform<strong>an</strong>ce <strong>of</strong> the <strong>dual</strong><br />

<strong>stator</strong> <strong>winding</strong> squirrel-cage <strong>induction</strong> machine. Based on the general <strong>winding</strong> function<br />

approach laid out in Section 3.3, the calculations <strong>of</strong> all the mutual <strong>an</strong>d self induct<strong>an</strong>ces<br />

under the static, dynamic <strong>an</strong>d mixed eccentricity conditions are presented<br />

comprehensively in Sections 4.2-4.4. The waveforms <strong>of</strong> the induct<strong>an</strong>ces under different<br />

eccentricity conditions are fully displayed for the first time in Section 4.4. Using these<br />

calculated induct<strong>an</strong>ces, the computer simulation method to study the starting tr<strong>an</strong>sient<br />

<strong>an</strong>d steady-state operations is provided in Section 4.5. Spectral <strong>an</strong>alysis <strong>of</strong> the steady-<br />

state waveforms shows the presence <strong>of</strong> high-order currents <strong>an</strong>d the high frequency<br />

153

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