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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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When k = 100 , the simulation results <strong>of</strong> the pole-shift method with a positive slip<br />

s<br />

frequency (corresponding to the motoring condition) <strong>an</strong>d negative slip frequency<br />

(corresponding to the generating condition) are given in Figure 10.14 <strong>an</strong>d Figure 10.15<br />

respectively. The poles <strong>of</strong> the machine are blue while the poles <strong>of</strong> the observer are<br />

marked in red in the figures.<br />

The effectiveness <strong>of</strong> the pole-shift method for high rotor speed are demonstrated in<br />

the simulation results given in Figure 10.14 <strong>an</strong>d Figure 10.15, however the method does<br />

not work well at the low speed r<strong>an</strong>ge since one <strong>of</strong> the poles from both the machine model<br />

<strong>an</strong>d the observer approach the imaginary axis when rotor speed is close to zero.<br />

Since the pole-shift method c<strong>an</strong>not achieve the desired pole movement at the low<br />

speed r<strong>an</strong>ge, the Butterworth method, which is straightforward <strong>an</strong>d simpler to use, has<br />

been chosen as the design method adopted.<br />

Figure 10.14 The poles <strong>of</strong> the machine <strong>an</strong>d the observer under motoring condition for the 2-pole<br />

<strong>winding</strong> set<br />

386

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