1 3 1/3 1/3 yes no -22-19 wye-delta -22-20 auto- 2 2 - - PowerPoint PPT Presentation

IEV 411 Starting method winding current % mains current % torque % interruption starting time critical

• 22-18

direct

• no

no

• 22-26

series-parallel 1/2 1/4 1/4 yes no

• 22-19

wye-delta

1 ⁄ √3

1/3 1/3 yes no

• 22-20

auto- transformer α α2 α2

• 22-21

with 2 switches α α2 α2 yes no

• 22-22

with 3 switches α α2 α2 no no

• 22-23

stator inductance α α α2 no yes

• 22-25

stator resistance α α α2 no yes Table 1 Classical starting methods

jXml (jxml) (jx2) jX'2 (jx1) jX1 R'2/s (r2/s) R1 (r1) I1 (i1) V1 (v1) I'2 (i2) Iml (iml) E1 + _ + _ jXm (jxm) (jx) jX R/s (r/s) I1 (i1) V1 (v1) I (i) Im (im) + _ X = X + X = (1+ )X = X

m l ml l ml l

• l

X 1

• X = X (1+ )+X' (1+ ) =
• l

l 2 l

• 2

R = (1+ ) R' = ' /(1+ )

• l

2 2 l 2

I I (a) (b)

s/r t il 1 2 3 1 1 x (b) im il i vl (a)

tmin tmax tpo n n-1 2 1 s1 s2 so sn s =1

n+1

t s

• r

r sy

= /

(c)

r =0,05

2

0,05 0,15 0,35 0,7 1,4 2,8

(b)

r =0,05

2

A B C D E 0,05 0,1 0,2 0,4 0,8 (a)

2 1 0 1 0,5 s t

Ru Ru Ru (a) (b) r

w

r

• rr

2rr 4rr 8rr rr 2rr 4rr 16rr 20rr 24rr 32rr rr 2rr 4rr

• II

III Ib Ia t

• r

r sy

= / 1

• 1

1

• 1

1 > > 0

• l > s >

: motoring

• Pem1

sPem1 Pem1 (1-s)Pem1 P =(s- )P

j2 em1

• P2

Pm Pm P =(s- )P

j2 em1

• P2

Pem1 sPem1 (1-s)Pem1 Pem1 s > 1 > : reverse braking

• Pem1

Pm P2 (1-s)Peml Peml (s- )P

• eml

Pj2 s > 1 > 0 > : reverse braking

• P2

Pem1 Pem1 (1-s)Pem1 Pm P =(s- )P

j2 em1

• l > s >

: motoring

• 0 >

> s : generating

• Pem1

Pm P2 sPem1 (1-s)Pem1 Pem1 P =(s- )P

j2 em1

• > s : generating

Pem1 Pm P2 Pj2 (1-s)Pem1 Pem1 (s- )P

• em1

(here s > 0) 0 > Pem1 sPeml P2Pem1 (1-s)Pem1 positive sign references :

(URS primary, GRS secondary)

(here s < 0) Pem1 P =(s- )P

j2 em1

• :

adjustable DC source Eg Em s0 1 s

• r

r sy

= / E =K. . (1-s)

g sy

E = k.E = k.s.E'

m 2 1

• 1

(a) (b)

P <0 P >0 P >0 (P >0)

m eml 2 em2

P >0 P >0 P >0 (P >0)

m eml 2 em2

P <0 P <0 P <0 (P <0)

m eml 2 em2

P <0 P <0 P <0 (P >0)

m eml 2 em2

P <0 P >0 P <0 (P >0)

m eml 2 em2

P >0 P >0 P <0 (P >0)

m eml 2 em2

P >0 P >0 P <0 (P <0)

m eml 2 em2

P <0 P <0 P >0 (P >0)

m eml 2 em2

2 2 1 1

• 2

1 1 1 2

• 1

(b) (a) (0) (c)

• s

s s generator generator motor reverse braking reverse braking motor motor 0> 1> >0

( c) r

w

r (b) r

w

r (a)

slip energy conversion 50Hz (a) (b)