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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>stator</strong> <strong>winding</strong>s were used as flux sensors. The searching coil has been used in the control<br />

<strong>of</strong> <strong>an</strong> <strong>induction</strong> machine in [10.8]. The problems in flux measurement have been<br />

identified. Optimal flux coil configuration has been developed to overcome those<br />

problems.<br />

1.2.10 Induction Machine Drive---Direct Torque Control<br />

Direct torque control, in which the torque <strong>an</strong>d flux are regulated directly by the<br />

hysteresis controller, is based on the estimation <strong>of</strong> electromagnetic torque <strong>an</strong>d flux. The<br />

PWM generator <strong>an</strong>d the coordinate tr<strong>an</strong>sformations that are required in the field<br />

orientation control are not necessary, becoming the main adv<strong>an</strong>tages <strong>of</strong> the method. The<br />

control scheme itself requires little machine parameter information, however the<br />

knowledge <strong>of</strong> those machine parameters are required for the torque <strong>an</strong>d flux estimation.<br />

Hence the similar problem--machine parameters dependency c<strong>an</strong> also be found in this<br />

control method. Some signific<strong>an</strong>t torque ripples are also found in the low speed r<strong>an</strong>ge <strong>an</strong>d<br />

are difficult to eliminate.<br />

From the above discussion, it seems that the control methods for <strong>induction</strong> machine<br />

are a mature technology. Future development <strong>of</strong> this area lies in the elimination <strong>of</strong> all<br />

kinds <strong>of</strong> sensors without degrading the perform<strong>an</strong>ce.<br />

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