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<strong>NTNU</strong><br />

<strong>NTNU</strong><br />

<strong>NTNU</strong><br />

Slide 385<br />

us<br />

Slide 387<br />

Slide 389<br />

Utledning av ekvivalentskjemaer<br />

■ Stasjonære forhold:<br />

u s = rs<br />

⋅ is<br />

+ � ⋅ f s ⋅ ψ s<br />

0 = rr<br />

⋅ i r + �⋅<br />

f r ⋅ ψ r<br />

f r = f s − n<br />

m e =<br />

T ( is<br />

) � ψ s<br />

■ Flukser og magnetiseringsstrøm:<br />

k k k<br />

iμ<br />

= is<br />

+ i r<br />

x s = x h + x sσ<br />

ψ = x s ⋅ is<br />

+ x h ⋅ i r = x s i s x h i<br />

s<br />

σ ⋅ + ⋅ μ<br />

ψ r = x h ⋅ i s + x r ⋅ i r = x rσ<br />

⋅ i r + x h ⋅ i μ<br />

ψ = x s s ⋅ is<br />

+ x h ⋅ i r<br />

ψ = x r h ⋅ is<br />

+ x r ⋅ i r<br />

x r = x h + x rσ<br />

Ekvivalentskjema basert på rotorfluks<br />

■ Spenningsbalanser:<br />

x h<br />

u s = ( rs<br />

+ �⋅<br />

f s ⋅ x σ ) ⋅ i s + � ⋅ f s ⋅ ⋅ i<br />

1 + σ<br />

f s rr<br />

x h<br />

0 =<br />

⋅ ( 1+<br />

σ r ) ⋅ i<br />

2<br />

r + �⋅<br />

fs<br />

⋅ ⋅ iμr<br />

f ( 1 + σ )<br />

1+<br />

σ<br />

r<br />

�� σ � �� �<br />

r<br />

�<br />

μr<br />

r<br />

is ( 1 + σr<br />

) ⋅ ir<br />

r<br />

Trondheim 2000<br />

��<br />

�� �<br />

1+ σ<br />

iμr<br />

u μr<br />

� �<br />

�<br />

�<br />

� = ⋅<br />

��<br />

2<br />

( 1+<br />

σ ) �<br />

�<br />

�<br />

Konstant statorfluks<br />

■ Sammenheng spenning, frekvens og fluks:<br />

u s = rs<br />

⋅ i s + � ⋅ f s ⋅ ψ ≈ � ⋅ f s s ⋅ ψ s<br />

■ Klassisk styring av fluks<br />

2<br />

⎛ rs<br />

⎞ 2<br />

u s = ψ s ⎜ + f s ≈ ψ s ⋅ f s<br />

x ⎟<br />

⎝ s ⎠<br />

■ Moment ble styrt med statorfrekvens:<br />

f r s<br />

= f − n<br />

2<br />

1 f r ⋅ ωn<br />

⋅ Tr<br />

⎛ x h ⎞<br />

’<br />

me = ⋅<br />

⋅ 2<br />

s Tr<br />

x<br />

’ ⎜ ⋅ ψ<br />

= σ ⋅<br />

r 1 ( f r n Tr<br />

) x ⎟<br />

+ ⋅ ω ⋅ ⎝ s ⎠<br />

Trondheim 2000<br />

T<br />

r<br />

Trondheim 2000<br />

<strong>NTNU</strong><br />

<strong>NTNU</strong><br />

<strong>NTNU</strong><br />

us<br />

Slide 386<br />

us<br />

Slide 388<br />

Slide 390<br />

Utledning av ekvivalentskjemaer…..<br />

■ Setter inn spenningslikingene:<br />

u = ( r + � ⋅ f ⋅ x ) ⋅ is<br />

+ � ⋅ f ⋅ x ⋅ i<br />

s<br />

s<br />

s<br />

sσ<br />

⎛ f s<br />

⎞<br />

0 = ⎜ rr<br />

+ �⋅<br />

f s ⋅ x rσ<br />

⎟ ⋅ i r + � ⋅ f s ⋅ x h ⋅ iμ<br />

⎝ f r<br />

⎠<br />

�� � �σ<br />

�<br />

�� is<br />

s<br />

h<br />

� � � ��<br />

μ<br />

i<br />

ir<br />

μ<br />

� �σ<br />

� ��<br />

Ekvivalentskjema basert på rotorfluks<br />

■ Definisjoner og sammenhenger:<br />

u<br />

ψ<br />

r<br />

μr<br />

= � ⋅ f s = �<br />

1 + σr<br />

ψr<br />

α<br />

�� σ � �� �<br />

ψr<br />

β<br />

x<br />

⋅ fs<br />

1+<br />

h<br />

σ r<br />

is ( 1 + σr<br />

) ⋅ ir<br />

�<br />

⋅ i<br />

k<br />

μr<br />

is = i r is<br />

= ( 1 + σ r ) ⋅ i r<br />

μ<br />

�<br />

� ⋅ �<br />

�<br />

�<br />

�<br />

Trondheim 2000<br />

��<br />

�� �<br />

1+ σ<br />

iμr<br />

u μr<br />

� �<br />

�<br />

�<br />

� = ⋅<br />

��<br />

2<br />

( 1+<br />

σ ) �<br />

�<br />

�<br />

Konstant U/f<br />

■ Sammenheng spenning, frekvens og fluks:<br />

u = � ⋅ f ⋅ ψ ⇒ u = ψ ⋅ f<br />

1<br />

f rk =<br />

’<br />

ωn<br />

⋅ Tr<br />

2<br />

1 ⎛ x h ⎞<br />

m e,<br />

max = ⋅<br />

s<br />

2 x ⎜ ⋅ ψ<br />

r x ⎟<br />

⋅ σ ⋅ ⎝ s ⎠<br />

s<br />

s<br />

s<br />

3<br />

2<br />

1<br />

0<br />

-1<br />

-2<br />

s<br />

s<br />

-3<br />

0 0.5 1 1.5 2<br />

s<br />

Fra venstre:<br />

f s ,u s = 0.2<br />

f s ,u s = 0.4<br />

f s ,u s = 0.6<br />

f s ,u s = 0.8<br />

f s ,u s = 1.0<br />

f s =1.2, u s = 1.0<br />

f s =1.4, u s = 1.0<br />

f s =1.6, u s = 1.0<br />

Trondheim 2000<br />

Trondheim 2000

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