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an investigation of dual stator winding induction machines

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Butterworth polynomial with the denominator <strong>of</strong> the tr<strong>an</strong>sfer functions. Similar tr<strong>an</strong>sfer<br />

functions for the state variables are determined for the 6-pole XYZ <strong>winding</strong> set. The<br />

same design idea will be applied to calculate the parameters <strong>of</strong> the controllers for the 6-<br />

pole <strong>winding</strong> set. The zeros <strong>of</strong> the tr<strong>an</strong>sfer functions also greatly influence the system<br />

perform<strong>an</strong>ce. When <strong>an</strong>y zero <strong>of</strong> a tr<strong>an</strong>sfer function <strong>of</strong> a system has positive real part (the<br />

system is non-minimum phase), the closed-loop perform<strong>an</strong>ce is compromised as the right<br />

half-pl<strong>an</strong>e zero induces additional phase shift <strong>of</strong> -180. The determination <strong>of</strong> controller<br />

parameters should ensure the minimum phase system requirement. In this case, the<br />

requirement c<strong>an</strong> be ensured when k p <strong>an</strong>d k i <strong>of</strong> a controller have the same sign. The<br />

controller parameters for the simulation <strong>of</strong> parallel connected generating system are given<br />

in Table 8.1. The final control scheme is shown in Figure 8.4. Since the equations for the<br />

d-axis current controller, the slip calculation <strong>an</strong>d the comm<strong>an</strong>d voltages calculations <strong>of</strong><br />

the 6-pole XYZ <strong>winding</strong> set are similar to those <strong>of</strong> the 2-pole ABC <strong>winding</strong> set, they are<br />

eliminated in Figure 8.4.<br />

To achieve field orientation control, the reference q-axis flux linkage is set equal to<br />

zero <strong>an</strong>d the d-axis flux linkage reference is equal to the magnitude <strong>of</strong> the rotor flux<br />

linkage given in (8.21) while the dc voltage is regulated. Although the control structure<br />

<strong>an</strong>d design set forth applies to the <strong>dual</strong> <strong>stator</strong>-<strong>winding</strong> connected to parallel connected<br />

rectifiers, the same approach applies for the machine with series connected rectifiers.<br />

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