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an investigation of dual stator winding induction machines

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10.12 Conclusions<br />

In the first part <strong>of</strong> this chapter, a speed control scheme for the <strong>dual</strong> <strong>winding</strong> <strong>induction</strong><br />

machine with a speed sensor has been proposed. The principles <strong>of</strong> input-output<br />

linearization have been applied to the control system design so that the coupling <strong>an</strong>d<br />

interaction terms are removed <strong>an</strong>d the classic linear design methods are applied for<br />

controller design. The controller design methodology based on the Butterworth method<br />

has been adopted. A torque partition factor K has been introduced to distribute the<br />

electromagnetic torque to each <strong>of</strong> the <strong>winding</strong> sets. By ch<strong>an</strong>ging the value <strong>of</strong> K, one<br />

<strong>winding</strong> set c<strong>an</strong> move smoothly from motoring condition into generating condition. The<br />

effectiveness <strong>of</strong> the torque partition factor has been demonstrated by simulation results.<br />

In the second part <strong>of</strong> this chapter, a speed sensorless control scheme based on full-order<br />

flux observer using MRAS technique has been <strong>an</strong>alyzed. A novel error function has been<br />

proposed to ensure stability within the ultra-low speed r<strong>an</strong>ge. The Butterworth method is<br />

used to design the observer gains. The tr<strong>an</strong>sfer function <strong>of</strong> the estimated <strong>an</strong>d actual<br />

speeds is derived based on the error <strong>an</strong>alysis, which is used to determine the parameters<br />

<strong>of</strong> the speed estimator for the sensorless control. The D-decomposition method is the<br />

design methodology for both the speed estimator <strong>an</strong>d the speed controller. Both the rotor<br />

speed <strong>an</strong>d slip frequency are varied within the possible operating r<strong>an</strong>ge to ensure the<br />

stability <strong>of</strong> the system based on the selected parameters. The whole system is simulated<br />

in both motoring <strong>an</strong>d generating modes. The controllers are shown to work properly <strong>an</strong>d<br />

the rotor speed is regulated accurately, validating the proposed full-order flux observer<br />

<strong>an</strong>d speed estimation methodologies.<br />

420

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