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an investigation of dual stator winding induction machines

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*<br />

ωr<br />

*<br />

ωr<br />

+<br />

+<br />

−<br />

ωr<br />

k<br />

p +<br />

ki<br />

s<br />

*<br />

ωr<br />

355<br />

+<br />

−<br />

ωr<br />

ki<br />

k p + + kd<br />

s<br />

s<br />

(a) (b)<br />

−<br />

ωr<br />

k p<br />

+<br />

−<br />

s<br />

k d<br />

ωr<br />

*<br />

ωr<br />

(b) (d)<br />

Figure 10.2 Controller structures, (a) diagram <strong>of</strong> PI controller, (b) diagram <strong>of</strong> PID controller, (c)<br />

diagram <strong>of</strong> PD controller, (d) diagram <strong>of</strong> IP controller.<br />

The pole placement method used in this design is called the Butterworth method, in<br />

which the parameters are selected to locate the eigen-values <strong>of</strong> the tr<strong>an</strong>sfer function<br />

uniformly in the left half <strong>of</strong> the s-pl<strong>an</strong>e, on a circle <strong>of</strong> radius ω 0 , with its center at the<br />

origin. The poles are evenly distributed around the circle. The example <strong>of</strong> pole placement<br />

for a second order system is given in Figure 10.3.<br />

The design steps using the Butterworth method are: firstly, the tr<strong>an</strong>sfer function <strong>of</strong> the<br />

controller is obtained; then the denominator <strong>of</strong> the tr<strong>an</strong>sfer function is compared with the<br />

Butterworth polynomial by equaling the coefficient <strong>of</strong> each term. Since the Butterworth<br />

polynomial is expressed only in term <strong>of</strong> ω 0 , if the value <strong>of</strong> ω 0 is selected, all the<br />

controller parameters c<strong>an</strong> be obtained.<br />

+<br />

−<br />

ωr<br />

ki s<br />

+<br />

k p<br />

−<br />

ωr

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