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解:閉環(huán)傳遞函數(shù)S

+1110

10

1+

10

S

+1f(S

)=

S

+1

=10s

+

1r(t)

c(t)-5-2.(3).r(t)=sin(t

+300

)-2

cos(2t

-450

)求穩(wěn)態(tài)輸出Css

(t)及穩(wěn)態(tài)誤差ess

(t)E(s)0

0

0則:Css1

(t)

=

0.905sin(t

+

30

-

5.2 )

=

0.905sin(t

+

24.8

)11f(

jw

)

=

-arctg

ww

2

+11210f(

jw

)

=jw

+1110f(

jw

)

=1當(dāng)r

(t

)=sin(t

+30

0

)時,w

=1則:f(j)=0.905f(

j)

=

-5.202當(dāng)r

(t

)

=

2

cos(

2t

-

450

)時

w

=

2f(

j2)

=

0.89

f(

j2)

=

-10.30\

C

(t)

=1.78

cos(2t

-

450

-10.30

)

=1.78

cos(2t

-

55.30

)ss

2\穩(wěn)態(tài)輸出:C

(t)

=C

(t)

-C

(t)

=0.905sin(t

+24.80

)

-1.78cos(2t

-55.30

)ss

ss1

ss2求穩(wěn)態(tài)誤差時,誤差傳遞函數(shù):S+111+

10

1

=

S+1R(S

)G

(S

)

=

E(S

)

=S

+1E1對r

(t

)=sin(t

+30

0

)w

=111w

2

+112w

2

+1GE

(

jw

)

=

GE

(

jw

)

=

arctgw

-

arctgwEjw

+11G

(

jw

)

=

jw

+10ess1

(t)

=

GE

(

j)

sin(t

+

30

+

GE

(

j))=

0.128sin(t

+

30

+

39.80

)

=

0.128sin(t

+

69.80

)e

(t)

=

2

G

(

j2)

cos(2t

-

450

+

G

(

j2))ss

2

E

E=

0.4

cos(2t

-

450

+

53.10

)

=

0.4

cos(2t

+8.10

)=

0.128sin(t

+

69.80

)

-

0.4

cos(2t

+8.10

)\

ess

(t)

=

ess1

(t)

-

ess

2

(t)5-6.繪制下列傳遞函數(shù)的幅相特性曲線。(4)幅相頻率特性:幅相特性曲線,即:Nyquist曲線,對數(shù)幅相頻率曲線

Bode圖,用對數(shù)坐標(biāo)紙畫。對數(shù)漸近幅頻特性曲線,只畫

L(w

)

漸近線即可。S

(S

2

+8S

+100)G(S

)=

1000(S

+1)

100寫成標(biāo)準(zhǔn)環(huán)節(jié)的形式

G(S

)=

10(S

+1)

S

(

S

2

+

0.08S

+1)(0.08w

2

)2

+

(w

-

0.01w

3

)2(-0.08w

2

)2

+

(w

-

0.01w

3

)210(0.92w

2

-

0.01w

4

)

-(0.08w

3

+w

-

0.01w

3

)

j10(

jw

+1)[-0.08w

2

-

(w

-

0.01w

3

)

j]G(

jw

)=

10(

jw

+1)

=

10(

jw

+1)

jw

(-0.01w

2

+

0.08

jw

+1)

-

0.08w

2

+

(1-

0.01w

2

)

jww

fi

0+\

lim

ReG(

jw

)

=

9.2==起點:-900終點:原點無窮遠處-

900

~

-1800~

-180000-

900

~

-9000S

+110

~

90S二階振蕩在第三象限jwfi

¥Vxw=0(5)無窮遠處原點相角特性j

(w

)=-2700

+arctgt

w

+arctgt

w1

2S

3G(S

)

=

k

(t1s

+1)(t2

s

+1)幅相頻率特性G(

jw

)

=

k

(t1

jw

+1)(t2

jw

+1)(

jw

)3-

2700起點w

=0終點w

fi

¥相角變化:三個積分環(huán)節(jié):-27000

~

9000

~

900~

-2700一個一階微分:一個一階微分:-

2700

~

-900第二、三象限w

3k[-(t

w

+t

w

)

+

(1-tt

w

2

)

j]=

1

2

1

2

w

3G(

jw

)

=

k

(t1

jw

+1)(t2

jw

+1)

=

k

(-t1w

+

j)(t2

jw

+1)-w

3

j則:fi

-¥=

limw

fi

0+w

fi

0+21w

3-

k

(t

w

+t

w

)lim

R

G(

jw

)ew=0jw

fi

¥0(5)圖(6)幅相頻率特性S

(TS

-1)G(S

)

=kjw

(Tjw

-1)G(

jw

)

=k由比例環(huán)節(jié),積分環(huán)節(jié),不穩(wěn)定環(huán)節(jié)組成j

(w

)

=

-900

-

(1800

-

arctgTw

)

=

-2700

+

arctgTwj

(0)

=

-2700j

(¥

)

=

-1800第二象限,起于-900無窮遠處,終于原點。(Tw

2

)2

+w

2k

(-Tw

2

+

jw

)G(

jw

)

==

-kT-

kTw

2lim

Re

G

(

jw

)

=

limw

fi

0

+2T

2w

4

+

wwfi

¥w

fi

0

+j0-KT(6)圖5-7.繪出下列函數(shù)的對數(shù)漸近幅頻特性和對數(shù)相頻特性(4)由2個積分環(huán)節(jié),1個慣性環(huán)節(jié),1個二階振蕩環(huán)節(jié)組成S

2

(S

2

+

S

+1)(6S

+1)50G(S

)

==1

交接頻率6=

121ww低頻段的對數(shù)幅頻特性:La

(w

)

=

20

lg

k

-

20n

lgw6n

=

2,

w

=

1則 處的分貝值為65(dB)61001-w

2j(¥

)

=

-4500j(1)

=

-350.5j(0)

=

-1800j(w

)

=

-1800

-

arctg

w

-1800

-

arctg6w w

>11-w

2j(w

)

=

-1800

-

arctg

w

-

arctg6w w

£16( )

=

-234.7j

1則可繪出對數(shù)幅頻特性和對數(shù)相頻特性曲線[-60][-100]1/6110-90

0-180

0-270

0-360

0-450

0wwdB

L(w)[-40]70605040302010(0)

0.1j

(

w

)(5)S

2

(S

+

0.1)寫成標(biāo)準(zhǔn)環(huán)節(jié)形式G(S

)

=

10(S

+

0.2)0.120

(

S

+1)S

2

(

S

+1)G(S

)=

0.2

w

1

=

0.1

fiw

2

=

0.2

fi慣性環(huán)節(jié)交接頻率一階微分環(huán)節(jié)交接頻率低頻段漸近對數(shù)幅頻特性:La

(w

)

=

20

lg

k

-

20n

lgw

=

26.02

+

40

=

66.02(dB)j

(w

)

=

-1800

-

arctg10w

+

arctg5wj

(0)

=

-1800

j

(0.1)

=

-198.40j

(0.15)

=

-199.440

j

(0.2)

=

-198.40j

(¥

)

=

-1800n

=

2,

w

=

0.1

k

=

20[-60][-40]1-450-900-1350-1800-225060504030201070wwdB

L(w)0.1[-40]j

(w)

(0)0.25-8.a)b)低頻段的對數(shù)幅頻特性:La

(w

)=20

lg

k

-20

lgw20

lg

k

=12

k

=

41

=100

T

=

0.01T0.01S

+14G(S

)

=SG(S

)

=

4(0.5S

+1)處

20

lg

k

-

20

lg

2

=

6則c)低頻段w

=

2k

=

4

t

=

0.5TS

+1G(S

)

=kSLa

(w

)

=

20

lg

k

-

20

lgww

=10

時,分貝值為0\

20

lg

k

+

20

lg10

=

0\

k

=

0.1d)或?qū)懗?.05S

+10.1S\

G(S

)

=T

=

0.05S

(TS

+1)(TS

+1)G(S

)

=kG(S

)

=n

nkww

2S

(

S

2

+

2x

S

+1)1個積分環(huán)節(jié),2個慣性環(huán)節(jié)一個積分環(huán)節(jié),一個二階振蕩環(huán)節(jié),但x

無法確定則:La

(w

)=20

lg

k

-20

lgww2\=

50

La

(50)

=

00

lg

k

-

20

lg

50

=

0k

=

50無法顯示該圖片。S

(0.01S

+1)2501

=100\

G(S

)

=\

T

=

0.01Te)S

(T1S

+1)(T2

S

+1)G(S

)

=k將w1

=0.5

代入La

(w1

)

=

20

lg

k

-

20

lgw

=

40

k

=

501=

0.5,T

=

211 40

-

0

=

-40

wlgw

-

lg

5f)=10

0

-(-12)

=

-40

wlg

5

-

lgw2222w\

T

=

1

=

0.1G(S

)=

k

(tS

+1)

S

(T1S

+1)(T2

S

+1)低頻段La

(w

)=20

lg

k

-20

lgww

=2

時La

(w

)=20則代入

20

lg

k

-

20

lg

2

=

20

k

=

2041

=

2

\

t

=

2111

=

4

\

T

=

1Tt設(shè)0分貝對應(yīng)的頻率值為wcc則:

20

-

0

=

-20

w

=

40lg

4

-

lg

wc40404S

(

S

+1)(

S

+1)20(

1

S

+1)\

G(S

)=

2

2\

T

=

121

=

40T5-9.a)b)S

2

(S

+1)G(S

)

=

0.1(10S

+1)G(S

)=

k

(tS

+1)

nw

nw

2S

(

S

2

+

2x

S

+1)含有一個積分環(huán)節(jié),一個一階微分環(huán)節(jié),一個二階振蕩環(huán)節(jié)低頻段:La

(w

)=20

lg

k

-20

lgww

=

1

La

(w

)

=

20

k

=

100.1

0.21

2.510

201000db40db-20db-40dbL(ω)ω28db20db120

lg2x

1-x22x20

lg

1=2.5

二階振蕩環(huán)節(jié)的交接頻率1

=1

t

=1

wntx用誤差來求。w

=w

nDL(w

,x)

=

-

20

lg

(1-w

2

w

2

)2

+(2xw

w

)2n

n=L精(w

)-L漸(w

)=28

-20

=8則可求得x

=0.2:或者20

lg

1

=

28

-

20

=

82x也可求得x

=0.2c)SS

2S

(

+

2

·0.2

·

+1)2.52

2.5\

G(S

)=

10(S

+1)

3+1)(T

S

+1)'''SS

2SS

22nG(S

)=

n

n

(

+

2xnwwk

(

+

2x

+1)w

2

w低頻段

La

(w

)

=

20

lg

k

-

20

lgww

=1

20

lg

k

=

-20

k

=

0.1二階微分環(huán)節(jié)的交接頻率:w

n

=

3.06則:n設(shè)二階振蕩環(huán)節(jié)的交接頻率為w

'4001

-

20

-

20

=

-40lgw

-

lgw

'n

nT

=n\

w

'

=

30.6=L精(w

)-L漸(w

)=-28

-(-20)

=-8DL(w

,x)

=

-

20

lg

(1-w

2w

=w

nw

2

)2

+(2xw

w

)2n

nn則:x

=0.2=L精(w

)-L漸(w

)=14

-20

=-6則:x'

=1w

=w

'DL(w

'

,x'

)

=

-

20

lg

(1-w

2nw

2

)2

+(2x'w

w

'

)2n

nn則:+1)3.06

3.06(

+

2

·

+1)(

+1)3.062

3.06

4000.1(

+

2

·0.2

·G(S

)

=S

SS

2S

2S5-12.1)S

(0.2S

+1)100G(S

)

=j

(w

)

=

-900

-

arctg0.2wj

(0)

=

-900

j

(¥

)

=

-1800畫Bode圖w

=1

處分貝值:20

lg

k

=

20

lg

100

=

4010-900-1800100wc20[-20]40wwdB

L(w)1[-40]j

(

w)

(

0)5P=0(開環(huán)傳遞函數(shù)在右半平面的極點個數(shù))N+

=

0

N-

=

0

N

=

N+

-

N-

=

0則:Z

=P

-2N

=0解:

w

c

為開環(huán)截止頻率,則

A(w

c

)

=1則\系統(tǒng)穩(wěn)定=1100ccw

(0.2w

)2

+1或用斜率法w

=5時的分貝值為:則:

26

-

0

=

-40

w又

對數(shù)相頻曲線經(jīng)過

-1800

線,\h

=¥

幅值裕度520

lg

100

=

26(dB)=

22.36lg

5

-

lgwcc=

-167

.4

00j

(w

c

)

=

-90

-

arctg

0.2w

cg

=1800

+j

(w

)

=12.60c(相角裕度)3)S

(0.2S

+1)(S

-1)10G(S

)

=j

(w

)

=

-900

-

arctg0.2w

-

(1800

-

arctgw

)=

-2700

+

arctgw

-

arctg0.2wj

(¥

)

=

-2700j

(5)

=

-236.30j

(0)

=

-2700j

(1)

=

-213.70交接頻率:w1

=1=

50.2=

12w畫Bode圖,w

=1

處分貝值20

lg

k

=20補齊9001Z

=

P

-

2(N2=

1--

N

)

=1+

2

· =

22++N

=

0

P=1-N\

系統(tǒng)不穩(wěn)定[-20]wc2040wwdB

L(w)1j(w)

(0)[-40]510[-60]-900-1800-2700而:=

-40

w

c

=

3.2lg1-

lgw20

-

0c0

0j

(w

c

)

=

-270

+

arctgw

c-

arctg0.2w

c

=

-229.97g

=1800

+j

(w

)

=

-500c又相頻曲線沒有穿越-1800線\w

x

(相角交界頻率)不存在\h

=

¥5-13.開環(huán)傳遞函數(shù)為則:即G(S

)

=

aS

+1S

2j

(w

)

=

-1800

+

arctgaww

2(aw

)2

+1L(w

)

=

20

lg相頻特性對數(shù)幅頻特性則要求相角裕度,先求開環(huán)截止頻率wccL(w

)

=

0=1cw

22(aw

c

)

+1解得:則相頻特性j

(w

)=-900

-arctgw

+arctg(-w

)=

-900

-

2arctgww

c

=1.189a

=

0.84g

=1800

-1800

+

arctgaw

=

arctgaw

=

450

aw

=1c

c

cS

(S

+1)5-

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