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Direct Power and Torque Control of AC/DC/AC Converter-Fed ...

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2. Voltage Source <strong>Converter</strong>s – VSC<br />

1 1<br />

g = =<br />

(2.13)<br />

w L L − L<br />

S<br />

r<br />

2<br />

M<br />

Equations (2.7) <strong>and</strong> (2.8) can be rewritten:<br />

I<br />

S<br />

Lr<br />

LM<br />

= ΨS<br />

− Ψr,<br />

(2.14)<br />

w w<br />

Lr<br />

LM<br />

Ir<br />

= Ψr<br />

− ΨS ,<br />

w w<br />

(2.15)<br />

In the case <strong>of</strong> a squirrel cage motor U = 0 . Therefore, the block diagram in<br />

stationary αβ coordinates can be constructed as in Fig. 2. 7. [16].<br />

r<br />

R S<br />

U Sα<br />

+<br />

−<br />

1<br />

s<br />

Ψ S α<br />

L R<br />

+<br />

−<br />

g<br />

I S α<br />

L M<br />

−<br />

U Sβ<br />

+<br />

−<br />

1<br />

s<br />

R S<br />

Ψ Sβ<br />

L R<br />

STATOR<br />

+<br />

L M<br />

−<br />

g<br />

I Sβ<br />

m s p<br />

b<br />

2<br />

M e<br />

−<br />

M L<br />

−<br />

−<br />

R r<br />

1<br />

s<br />

Ψ r<br />

L S<br />

+<br />

L M<br />

−<br />

g<br />

I rα<br />

1<br />

sJ<br />

Ω m<br />

p b<br />

L M<br />

+<br />

−<br />

1<br />

s<br />

R r<br />

Ψ r<br />

αβ<br />

L S<br />

ROTOR<br />

+<br />

−<br />

g<br />

I rβ<br />

1 1<br />

g = =<br />

w L L −<br />

s<br />

r<br />

2<br />

L<br />

M<br />

Fig. 2. 7. Model <strong>of</strong> an induction motor - in stationary αβ coordinates<br />

17

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