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an investigation of dual stator winding induction machines

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L L L L L L L<br />

λ +<br />

lr1<br />

m1<br />

ls1<br />

m1<br />

lr 2i<br />

m2<br />

ls2<br />

m2<br />

m = λds1<br />

+ λdr1<br />

+ λds2<br />

λdr<br />

2<br />

(6.19)<br />

D1<br />

D1<br />

D2<br />

D2<br />

No load tests were conducted on <strong>an</strong> experimental 2 hp machine to determine the<br />

magnetizing induct<strong>an</strong>ces. The other parameters which are considered const<strong>an</strong>t are<br />

determined using well-known methods <strong>of</strong> short circuit <strong>an</strong>d dc tests. For the no-load test<br />

<strong>an</strong>d the machine running at close to the synchronous speed, the phase voltage <strong>of</strong> the 2-<br />

pole <strong>winding</strong> set was varied while the 6-pole <strong>winding</strong> set was opened. In the second run,<br />

the 2-pole <strong>winding</strong> set was opened while the phase voltage <strong>of</strong> the 6-pole <strong>winding</strong> set was<br />

varied from zero to the rated value. Finally, the phase voltage <strong>of</strong> the 2-pole <strong>winding</strong> set<br />

was fixed at three values <strong>an</strong>d for each fixed value, the phase voltage <strong>of</strong> the 6-pole<br />

<strong>winding</strong> set was varied from zero to the rated voltage. Similar experiments were<br />

conducted for three fixed values <strong>of</strong> the phase voltage <strong>of</strong> the 6-pole <strong>winding</strong> set.<br />

The magnetizing induct<strong>an</strong>ces <strong>of</strong> the 2hp <strong>dual</strong>-<strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine are<br />

shown in Figure 6.6 for the various tests. Polynomials expressing the magnetizing<br />

induct<strong>an</strong>ces as a function <strong>of</strong> the unsaturated total air-gap flux linkage are determined. As<br />

shown in Figure 6.6, they closely follow the experimental data. In the presented computer<br />

simulations, the calculated total air-gap flux linkage is used with the polynomial<br />

equations to determine the correct d-axis magnetizing induct<strong>an</strong>ces as the two q-axis<br />

magnetizing induct<strong>an</strong>ces are held const<strong>an</strong>t at the unsaturated no-load values.<br />

247<br />

L

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