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an investigation of dual stator winding induction machines

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In this chapter, the flux observer parameters have been designed to ensure the stability<br />

over the whole speed r<strong>an</strong>ge. The stability problem for sensorless control are demonstrated<br />

by the pole-zero maps under the rotor speed varying within the whole speed r<strong>an</strong>ge. Two<br />

observer gain design methods have been studied <strong>an</strong>d compared. A new speed adaptive<br />

speed estimator is proposed <strong>an</strong>d its effectiveness is validated by the pole-zero map <strong>of</strong> the<br />

whole system.<br />

This section is org<strong>an</strong>ized as follows: first <strong>of</strong> all, the machine model <strong>an</strong>d full-order<br />

flux observer model in matrix form are derived. Then based on the error <strong>an</strong>alysis, the<br />

tr<strong>an</strong>sfer function <strong>of</strong> estimated speed <strong>an</strong>d actual rotor speed is obtained. The observer<br />

gains are determined from the tr<strong>an</strong>sfer function <strong>of</strong> the estimated speed <strong>an</strong>d actual rotor<br />

speed while the determination <strong>of</strong> the speed estimator gains is based on the tr<strong>an</strong>sfer<br />

function <strong>of</strong> estimated rotor speed <strong>an</strong>d reference rotor speed. The D-decomposition<br />

method is adopted to ensure the stability <strong>of</strong> the system. The whole controlled system is<br />

simulated in both motoring <strong>an</strong>d generating modes. It has been demonstrated that the<br />

whole system remains stable within the whole speed r<strong>an</strong>ge, all the controllers work<br />

properly <strong>an</strong>d the rotor speed is well regulated under different load conditions, validating<br />

the proposed method <strong>of</strong> designing full-order flux observer, speed estimator <strong>an</strong>d speed<br />

controller.<br />

10.6.1 Machine Model<br />

The complex variable form <strong>of</strong> the voltage equations for the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong><br />

<strong>induction</strong> machine expressed in the synchronous reference frames are given in (10.55-<br />

10.56). The three-phase <strong>winding</strong>s wound for P1 poles is called the ABC <strong>winding</strong> set<br />

368

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