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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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A recently developed <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> squirrel-cage <strong>induction</strong> machine is<br />

considered in this chapter [1.1, 1.10]. It is claimed that this innovation <strong>of</strong>fers the<br />

adv<strong>an</strong>tages <strong>of</strong> ease <strong>of</strong> sensor-less control (especially at low speeds), high reliability, full<br />

utilization <strong>of</strong> the <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d absence <strong>of</strong> circulating currents. It consists <strong>of</strong> a <strong>stator</strong><br />

with two separate symmetric three-phase <strong>winding</strong>s, having different numbers <strong>of</strong> poles 1 P<br />

<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 rotor. The machine used for the<br />

<strong>an</strong>alysis reported in this chapter has the number <strong>of</strong> poles as 2/6. The design process <strong>of</strong><br />

this machine has been clearly laid out in chapter 2.<br />

A model based on the machine geometry <strong>an</strong>d the <strong>winding</strong> layouts <strong>of</strong> <strong>an</strong> arbitrary n<br />

phase machine is required for a general machine <strong>an</strong>alysis. This is the motivation for the<br />

development <strong>of</strong> the multiple coupled circuit model <strong>of</strong> <strong>an</strong> <strong>induction</strong> machine set forth in<br />

[3.5]. Following this conceptual framework, this chapter presents a coupled circuit <strong>an</strong>d<br />

air gap field calculation model for the <strong>dual</strong> <strong>stator</strong> <strong>winding</strong> <strong>induction</strong> machine with<br />

squirrel-cage rotor. The induct<strong>an</strong>ces <strong>of</strong> the <strong>stator</strong> <strong>winding</strong>s <strong>an</strong>d rotor bars are calculated<br />

using the <strong>winding</strong> function methodology based on the actual distributions <strong>of</strong> the <strong>winding</strong>s<br />

<strong>an</strong>d the bars [3.6]. Unlike the technique based on the fundamental component <strong>of</strong> the<br />

<strong>stator</strong> <strong>winding</strong> distributions, the space harmonic components are included in the <strong>an</strong>alysis<br />

that follows. Another adv<strong>an</strong>tage <strong>of</strong> the model developed in this chapter is the possibility<br />

<strong>of</strong> calculating the currents flowing in the component parts <strong>of</strong> the machine. This includes<br />

<strong>stator</strong> coils <strong>an</strong>d rotor bars during tr<strong>an</strong>sient, dynamic <strong>an</strong>d steady state operating conditions.<br />

In view <strong>of</strong> this possibility, the approximate flux densities in the air gap <strong>an</strong>d cores <strong>of</strong> the<br />

machine c<strong>an</strong> be deduced.<br />

85

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