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an investigation of dual stator winding induction machines

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A novel error function is proposed in this dissertation to improve the stability <strong>of</strong> the<br />

speed estimator within the whole operating speed r<strong>an</strong>ge. The proposed error function is<br />

defined as:<br />

ε = k<br />

+<br />

*<br />

*<br />

{ Im[<br />

ˆ λ ( ˆ ) ] [ ˆ ( ˆ<br />

qdr1<br />

iqds1<br />

− iqds1<br />

+ k1<br />

Re λqdr1<br />

iqds1<br />

− iqds1)<br />

] }<br />

*<br />

*<br />

( 1−<br />

k)<br />

{ Im ˆ λ ( i − iˆ<br />

) + k Re ˆ λ i − iˆ<br />

}<br />

[ ] [ ( ) ]<br />

qdr 2<br />

qds2<br />

qds2<br />

2<br />

qdr 2<br />

392<br />

qds2<br />

qds2<br />

(10.117)<br />

where, k is a binary variable used to partition the error signals from two <strong>stator</strong> <strong>winding</strong>s<br />

<strong>an</strong>d k = 0 or 1;<br />

k 1 is used to ch<strong>an</strong>ge the effects <strong>of</strong> reactive power <strong>of</strong> the ABC <strong>winding</strong><br />

set; k 2 is used to ch<strong>an</strong>ge the effect <strong>of</strong> reactive power <strong>of</strong> the XYZ <strong>winding</strong> set.<br />

If the PI controller is used to generate the speed estimation, the estimated speed c<strong>an</strong><br />

be expressed as:<br />

ωˆ<br />

rm<br />

= G ⋅ε<br />

= G<br />

p<br />

⋅ε<br />

+ G<br />

i<br />

⋅<br />

∫<br />

ε dt<br />

where, ωˆ rm is estimated rotor mech<strong>an</strong>ical speed.<br />

(10.118)<br />

The error between the actual <strong>an</strong>d estimated states is needed to determine the tr<strong>an</strong>sfer<br />

function <strong>of</strong> the speed estimation. The error function definition <strong>an</strong>d its derivative have<br />

been given in (10.71-10.72).<br />

The derivative <strong>of</strong> the state error c<strong>an</strong> also be given as :<br />

0<br />

ei ( Ai<br />

Ki<br />

Ci<br />

) ei<br />

αi Xˆ<br />

⎡ ⎤<br />

& = − ⋅ ⋅ + ⋅ i − ⎢ ( ω ˆ ri −ω<br />

ri )<br />

jλ<br />

⎥<br />

⎣ qdri<br />

14243<br />

⎦<br />

Z<br />

(10.119)<br />

where α i = γ i − Ki ⋅∆C<br />

i .<br />

Hence,<br />

i<br />

−1<br />

[ p ⋅ I − A + K ⋅ C ] ⋅ α ⋅ Xˆ<br />

− Z ⋅ ( ω − ˆ )<br />

i<br />

i<br />

i<br />

i<br />

[ ]<br />

e =<br />

ω<br />

i<br />

i<br />

i<br />

ri<br />

ri<br />

(10.120)

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