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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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<strong>winding</strong> induced flux linkage which may reinforce or diminish the contribution <strong>of</strong> the 6-<br />

pole <strong>winding</strong> set to the effective air-gap flux density. The study indicates that <strong>an</strong><br />

underst<strong>an</strong>ding <strong>of</strong> the nature <strong>an</strong>d magnitudes <strong>of</strong> space harmonics in addition to the<br />

fundamental components rather th<strong>an</strong> the peak values alone or generalized average values<br />

<strong>of</strong> the two domin<strong>an</strong>t flux densities are import<strong>an</strong>t in the selection <strong>of</strong> the specific magnetic<br />

loading <strong>of</strong> the machine. The dynamic model <strong>of</strong> a <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine<br />

including the air gap main flux linkage saturation effect has also been presented. It is<br />

argued that in the light <strong>of</strong> experimental <strong>an</strong>d simulation results, the inter-<strong>winding</strong> induced<br />

flux linkages c<strong>an</strong> be ignored with little loss <strong>of</strong> prediction accuracy for the fundamental<br />

component state variables. A common reference frame speed is determined <strong>an</strong>d chosen<br />

for computer simulations to ensure that the inst<strong>an</strong>t<strong>an</strong>eous total air gap flux linkage due to<br />

the contributions <strong>of</strong> the two <strong>winding</strong>s <strong>of</strong> dissimilar pole numbers is aligned with the d-<br />

axis <strong>of</strong> the reference frame. Thus the main air-gap flux linkage saturation is included in<br />

the machine model by varying the saturation dependent d-axis magnetizing induct<strong>an</strong>ces<br />

<strong>an</strong>d setting the const<strong>an</strong>t q-axis magnetizing induct<strong>an</strong>ces to be equal to the unsaturated<br />

values. The resulting model is used to illustrate the differences in tr<strong>an</strong>sient <strong>an</strong>d dynamic<br />

perform<strong>an</strong>ce measures with <strong>an</strong>d without the inclusion <strong>of</strong> the saturation <strong>of</strong> the <strong>stator</strong> <strong>an</strong>d<br />

rotor teeth reflected in the air-gap flux density.<br />

Based on the steady state machine model in complex variable form, the steady state<br />

<strong>an</strong>alysis <strong>of</strong> <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine to explore the operability regimes <strong>of</strong><br />

the machine under const<strong>an</strong>t Volt/Hz control scheme has been presented. The relationship<br />

between the slip frequencies <strong>of</strong> two <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d the power contributions from<br />

442

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