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POLITECHNIKA WARSZAWSKA

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5. Speed estimation of induction motor<br />

a)<br />

isα<br />

usα<br />

usβ<br />

isβ<br />

αβ isx<br />

rs<br />

_<br />

usx<br />

esx 1<br />

Amplitude Ψsx<br />

= Ψs<br />

T Limiter<br />

N<br />

usy<br />

esy<br />

_<br />

isy<br />

xy rs<br />

÷<br />

esy<br />

ω<br />

s<br />

=<br />

sin γ s<br />

Ψsx<br />

cos ∫<br />

γ s<br />

b)<br />

+<br />

T dΨ sx<br />

= 1<br />

N<br />

esx<br />

Ψsx<br />

= Ψ<br />

dt<br />

s + ω<br />

s<br />

c y LPF<br />

+<br />

ωc<br />

s + ω<br />

c<br />

Limiter<br />

Fig. 5.3. Improved stator flux estimator in polar coordinates:<br />

a) stator flux estimator with amplitude limiter, b) amplitude limiter<br />

5.2.2.1. Luenberger Observer<br />

Luenberger observer (LO) is of the deterministic type and basically is applicable to<br />

linear time-invariant deterministic systems. The extended Luenberger observer (ELO)<br />

is applicable to nonlinear time-varying deterministic system.<br />

x&<br />

= Ax<br />

+ Bu<br />

i<br />

s<br />

= Cx<br />

s<br />

(5.8)<br />

where<br />

103

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