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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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The last is the recently developed <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> squirrel-cage <strong>induction</strong><br />

machine. This type is claimed to <strong>of</strong>fer adv<strong>an</strong>tages <strong>of</strong> ease <strong>of</strong> sensor-less control<br />

(especially at low speed), high reliability, full utilization <strong>of</strong> the <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d<br />

absence <strong>of</strong> circulating currents. It is the structure considered in this dissertation [1.1,<br />

1.10]. It consists <strong>of</strong> a <strong>stator</strong> with two separate symmetric three-phase <strong>winding</strong> sets, having<br />

different numbers <strong>of</strong> poles P 1 <strong>an</strong>d P 2 (e.g., 2/6 or 4/12) <strong>an</strong>d a st<strong>an</strong>dard squirrel-cage<br />

rotor. In principle, <strong>an</strong>y combination <strong>of</strong> different pole numbers could be used, however to<br />

better utilize the magnetic material, avoid localized saturation <strong>an</strong>d additional <strong>stator</strong><br />

losses, it is found that the most adv<strong>an</strong>tageous configuration should have a pole ratio <strong>of</strong> 1:<br />

3 [1.1]. Since a st<strong>an</strong>dard squirrel cage rotor is utilized, the cost <strong>of</strong> the machine decreases<br />

<strong>an</strong>d the adv<strong>an</strong>tages <strong>of</strong> squirrel cage rotor are inherited. Adv<strong>an</strong>tages include simple<br />

structures, easy connections, durability under severe operating conditions, low cost <strong>an</strong>d<br />

low mainten<strong>an</strong>ce. All these features make this kind <strong>of</strong> machine attractive in real industry<br />

applications.<br />

It is known from previous works that the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> squirrel-cage <strong>induction</strong><br />

machine c<strong>an</strong> be treated as two <strong>induction</strong> <strong>machines</strong> coupled through rotor shaft [1.1, 1.10],<br />

although, strictly speaking, some couplings between two <strong>stator</strong> <strong>winding</strong> sets are possible<br />

during the tr<strong>an</strong>sient process <strong>of</strong> the machine as shown in the chapter 5 <strong>of</strong> this dissertation.<br />

Hence the control methodologies applied to the single <strong>winding</strong> set squirrel-cage <strong>induction</strong><br />

machine c<strong>an</strong> also be used to control this <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine as shown<br />

in [1.1].<br />

The extensive industry applications <strong>of</strong> <strong>induction</strong> <strong>machines</strong> greatly benefit from the<br />

development <strong>of</strong> power electronics. At the very beginning, <strong>induction</strong> <strong>machines</strong> were used<br />

3

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