poles and zeros

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sridhara

Joined: 02 May 2006
Posts: 87
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04 Nov 2007 18:48 poles and zeros stability

where can i get a good material about poles and zeros....explanation in terms control systems and also in analog circuits.......

engrzz

Joined: 18 Oct 2007
Posts: 6

04 Nov 2007 19:42 poles and zeros

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jasmin_123

Joined: 01 Feb 2007
Posts: 218
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Location: Rio de Janeiro

04 Nov 2007 20:41 network analysis van valkenburg rapidshare

I also looked for the meaning of poles and zeros in analog circuits. This is what I have found:

Desoer & Kuh gives you the physical meaning of poles and zeros.

Poles in oscillators:
http://www.ee.bgu.ac.il/~paperno/1._Positive_Feedback_Oscillators_Illustrations.pdf

electronics_kumar

Joined: 29 Nov 2004
Posts: 664
Helped: 26
Location: Tamilnadu

05 Nov 2007 13:12 physical meaning of poles and zeros

for stable systems,pole should be in right hand of S plane (negative real value)and if it is imaginary axis(non real) ,it indicates system is oscillatory...
if it is real and imaginary( a complex),then system response is damped oscillation.....
if poles are left in Splane then system is highly unstable...

i.esmaili

Joined: 20 Oct 2007
Posts: 64
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Location: IRAN

05 Nov 2007 13:19 physical significance of poles and zeros

modern control system
dorf
control system
ogata
and me if u have some questions.

FrankCh

Joined: 18 Jul 2005
Posts: 53
Helped: 6

05 Nov 2007 15:21 modern control systems dorf rapidshare

Concept is very simple.

When you see a pole, the output from the transfer function give you a infinite value..
WHen you see a zero, the output is 0.

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05 Nov 2007 15:21 Ads

jasmin_123

Joined: 01 Feb 2007
Posts: 218
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Location: Rio de Janeiro

05 Nov 2007 16:44 effects of adding zero or pole in s-plane

i.esmaili wrote:

modern control system
dorf
control system
ogata
and me if u have some questions.

elec350

Joined: 17 Dec 2006
Posts: 255
Helped: 1
Location: Middle East

05 Nov 2007 18:05 control systems dorf rapidshare

hi
also I say you to see the books by:
1) Hayt
2) Dorf
3) Nelson

sridhara

Joined: 02 May 2006
Posts: 87
Helped: 3

05 Nov 2007 18:24 network analysis van valkenburg rapidshare

i want to know about the effect of addition of pole or a zero to a circuit....

electronics_kumar

Joined: 29 Nov 2004
Posts: 664
Helped: 26
Location: Tamilnadu

08 Nov 2007 4:04 physical significance fo poles and zeros

pole zero cancellation method can be used for cancellation techinque.........

amriths04

Joined: 15 Jul 2006
Posts: 241
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09 Nov 2007 15:01 explanation about poles and zeros

sedra and smith.

bas

Joined: 24 Mar 2006
Posts: 29
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09 Nov 2007 18:12 network analysis van valkenburg + rapidshare

sedra&smith is always a good book and you can find the definitions of poles and zeros and their realtion of the stability and the gain af any system in the book

chickoos

Joined: 18 Sep 2006
Posts: 29

10 Nov 2007 15:27 van valkenburg rapidshare

hi,
u can read the book "Network Analysis" by Van Valkenburg.
A very good introduction to poles and zeros is given in that book

ladymaly

Joined: 10 Nov 2007
Posts: 33
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10 Nov 2007 22:39 nyquist stability criterion

try this book http://rapidshare.com/files/39746545/Modern.Control.P.rar

sundarmeenakshi

Joined: 12 Dec 2006
Posts: 322
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11 Nov 2007 8:44 control system: poles and zero

ladymaly wrote:

try this book http://rapidshare.com/files/39746545/Modern.Control.P.rar

u can ref any sinals and system book

ladymaly

Joined: 10 Nov 2007
Posts: 33
Helped: 2

15 Nov 2007 22:22 van valkenburg network analysis rapidshare

Quote:

try this book http://rapidshare.com/files/39746545/Modern.Control.P.rar

sorry i 4got the psw: deadzoners.info

umairmahmood

Joined: 25 Apr 2009
Posts: 1

26 Apr 2009 0:10 stability poles and zeros

can anyone tell me what is the physical meaning of adding a pole and zero.I want to ask what we do in reality when we say
we added a pole to the system(what change or component ve we introduced in our construction)
we added a zero to the system

Added after 20 minutes:

addition of pole makes system less stable but decreases its steady state error .
adding a zero makes the system stable but its steady state error is increased.

xulfee

Joined: 27 May 2008
Posts: 431
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Location: Pakistan

27 Apr 2009 5:18 poles and zeros in circuits

see ogata's control system book of kou's book

santom

Joined: 08 Sep 2007
Posts: 132
Helped: 1

27 Apr 2009 12:04 meaning of pole in circuits

Can anyone tell me what is the physical meaning of adding a pole and zero.I want to ask what we do in reality when we say we added a pole to the system(what change or component ve we introduced in our construction) we added a zero to the system ...

A question repeated on behalf of our friend umairmahmood and also may persons like us..

Santom

LvW

Joined: 07 May 2008
Posts: 1594
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Location: Germany

27 Apr 2009 12:39 van valkenburg network analysis rapidshare.com

santom wrote:

OK - here is a short explanation:

1.) Adding a pole means to have an additional factor (1+sT) in the denominator of a transfer function. This can be done by using an additional lowpass of 1st order.
2.) If (1+sT) appears as an additional factor in the nominator it acts like a zero.
This can be accomplished - for example - by adding another R in series with the cap of the low pass circuit.

Added after 18 minutes:

umairmahmood wrote:

addition of pole makes system less stable but decreases its steady state error .
adding a zero makes the system stable but its steady state error is increased.

That´s definitely not true.
Have you ever heard about lag compensation - a method for stabilizing a circuit by adding a pole.

khanafzaal

Joined: 30 Nov 2007
Posts: 23
Helped: 1

29 Apr 2009 18:39 control systems poles and zeros stability

Here is what I understand poles and zeros of a system.

if you add a pole at say 1/t1, the gain of your system will start rolling-off
with -20dB/decade ,after frequency 1/t1. If you add another pole at
1/t2, an additional -20dB/decade will make it -40dB/decade from frequency
1/t2 onwards.

similarly if you add a zero to your system,the gain of your sytem increase
with +20dB/decade from that frequency.

poles and zeros

as you can see in the figure, the system has a pole at zero frequency,one
more pole is added at 1/T1, and a zero is added at 1/T2.

Adding more poles to a system increses order of the system,hence a system tends
to become unstable.So zeros are added at appropriate locations to stablize.
Zeros have direct effect on damping factor of the system.

In addition to this, adding a pole means lagging in phase(phase subtraction),where as addinga zero means phase leading(phase addition).

LvW

Joined: 07 May 2008
Posts: 1594
Helped: 261
Location: Germany

30 Apr 2009 8:11 network analysis by van valkenburg rapidshare

I know what you mean, but recognize: It depends WHERE you put the additional pole.
Think of the principle of universal compensation of opamps:
By placing an additional pole at a rather low frequency (10..100 Hz) the system is stabilized.
Therefore, one cannot say that in GENERAL a system becomes less stable by adding a pole. It really depends on the location of other poles and zeros.

santom

Joined: 08 Sep 2007
Posts: 132
Helped: 1

02 May 2009 2:39 effect of adding poles and zeros

Such a nice explanation by all the people.
Thanks so much

Well.One curious doubt which got raised from our friend LvW reply: Could you please tell us why its that way only in the lower frequencies.Then how come we can can make a stable system at higher frequencies if poles' addition makes it unstable

Santom

Santom

LvW

Joined: 07 May 2008
Posts: 1594
Helped: 261
Location: Germany

02 May 2009 8:37 zeros and poles

santom wrote:

.........................
Could you please tell us why its that way only in the lower frequencies.Then how come we can can make a stable system at higher frequencies if poles' addition makes it unstable

Stability of a system with feedback depends on the location of ALL poles and zeros.
In particular, it depends on the DOMINANT pole. If you add a pole at rather low frequencies which let´s the gain drop to 0 dB before other poles come into the play, the system will be always stable (gain slope -20 dB/decade).
Example:opamp with universal compensation.
However, if you add a 2nd pole BEFORE the gain has dropped to 0 dB, the gain slope increases and may cross the 0 dB line with nearly -40 dB/decade. This will be a system with bad stability properties or even an unstable system.
To understand the mentioned consequences you must be aware of the Nyquist stability criterion (in its simplified form).