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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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mutual induct<strong>an</strong>ces between the <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d the rotor circuits. The phase voltage<br />

<strong>an</strong>d torque equations thus obtained are further tr<strong>an</strong>sformed to the rotor reference frame to<br />

facilitate simplicity <strong>of</strong> model <strong>an</strong>d ease computational efforts. A new approach, using the<br />

<strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d rotor bar currents determined from the coupled-circuit model <strong>an</strong>d the<br />

<strong>winding</strong> functions <strong>of</strong> the <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d the rotor loops to generate the air gap flux<br />

density, has been presented for the first time. A simplified correction scheme, using the<br />

B-H curve <strong>of</strong> the magnetic steel material to account for magnetic saturation in the air gap<br />

was introduced, improving the prediction accuracy. Some measurements <strong>of</strong> no-load <strong>an</strong>d<br />

full load flux densities largely confirm the simulation <strong>an</strong>d FEA results.<br />

An <strong>an</strong>alysis <strong>of</strong> a <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine under rotor eccentricity<br />

conditions is presented. The method <strong>of</strong> calculating the induct<strong>an</strong>ces is based on the general<br />

<strong>winding</strong> function definition <strong>an</strong>d the <strong>winding</strong> function approach. The calculation <strong>an</strong>d<br />

waveforms <strong>of</strong> <strong>stator</strong>, rotor <strong>an</strong>d mutual induct<strong>an</strong>ces under rotor static, dynamic <strong>an</strong>d mixed<br />

eccentricity conditions are clearly set forth <strong>an</strong>d illustrated for the first time. The 2-pole<br />

<strong>winding</strong> set <strong>of</strong> the <strong>induction</strong> machine has the worst perform<strong>an</strong>ce in terms <strong>of</strong> generating<br />

more harmonic induct<strong>an</strong>ce components <strong>an</strong>d harmonic currents under rotor eccentricity<br />

conditions when it is compared to the other higher pole number <strong>stator</strong> <strong>winding</strong> set.<br />

Computer simulation <strong>of</strong> the starting tr<strong>an</strong>sient is presented under mixed eccentricity<br />

condition as also the steady-state perform<strong>an</strong>ce. The components <strong>of</strong> the currents <strong>an</strong>d<br />

electromagnetic torque are given indicating the presence <strong>of</strong> non-fundamental <strong>an</strong>d low<br />

order harmonics in currents <strong>an</strong>d torque induced by the presence <strong>of</strong> the eccentricity<br />

conditions.<br />

440

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