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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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Figure 7.6 Power factor speed characteristics when f = 5 Hz <strong>an</strong>d f = 15Hz<br />

The output torque <strong>of</strong> the <strong>dual</strong> <strong>winding</strong> <strong>induction</strong> machine is reduced at low speed<br />

r<strong>an</strong>ge. The XYZ <strong>winding</strong> set carries most <strong>of</strong> the load torque under the same const<strong>an</strong>t<br />

V/Hz condition.<br />

7.3.3 f = 25 Hz <strong>an</strong>d f = 90 Hz<br />

abc<br />

xyz<br />

The frequency ratio is greater th<strong>an</strong> 3 while the frequency <strong>of</strong> the ABC <strong>winding</strong> set is<br />

less th<strong>an</strong> the rated value in this case. The steady state curves under this condition are<br />

given in Figures 7.7-7.9. The ABC <strong>winding</strong> set is generating when the rotor speed is<br />

greater th<strong>an</strong> the synchronous speed <strong>of</strong> the ABC <strong>winding</strong> set while the XYZ <strong>winding</strong> set<br />

produces positive torque until the rotor speed reaches the synchronous speed <strong>of</strong> the XYZ<br />

<strong>winding</strong> set. The output torque <strong>of</strong> the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine is the sum <strong>of</strong><br />

the electromagnetic torques contributed by the two <strong>winding</strong> sets.<br />

265<br />

abc<br />

xyz

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