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# Electrical Engineering/Electronics and control systems

Question
QUESTION: Hello I studied both basics on electronics and control engineering, and I want to ask about the relationship of closed loop feedback and control theory and the electronics shunt shunt/series shunt / series series etc loops.
Like this R11 and R22 and feedback network and those A and B parameters. How do they relate to control theory? and do we study root loci and gain,steady state error  in such connections?

ANSWER: This is a very broad question and there are many directions one could follow.

Since you are or were a student of 'basics' in the field let me offer this short course in feedback and control theory.  It is a good overview of the principles of feedback and how systems can be quantified for design analysis and synthesis.

http://www.cds.caltech.edu/~murray/books/AM05/pdf/am08-complete_22Feb09.pdf

This ebook is more technical but has some good examples for multi-variant systems:

http://f3.tiera.ru/2/E_Engineering/Albertos%20P.,%20Sala%20A.%20Multivariable%20(Springer,2002)(ISBN%201852337389)(358s)_E_.pdf

The above will teach you alot about control systems.

You can find on google (or bing) many design examples and solutions for various feedback implementations.  Why don't you take that as assignment for your investigation then come back to me when you have narrowed it down to a specific area that we can focus on.  Concentrate of feedback stability, Nyquist point and tracing the loci of feedback system design which elements are central to all feedback operations, whether in the electronics domain (such as linear amplifiers) or motors or mechanical structures and digital representations.

Have a wonderful day.

---------- FOLLOW-UP ----------

QUESTION: Well the issue is all what we learned from Control theory applied to only linear systems with laplace transform, but that doesn't
apply to electronics so...
If I were to narrow it down then how does what we learn in control theory * which is only useful for linear time invariant system* apply to non linear electronic  devices?

Nonlinear analysis is mathematically unique but principles are the same.  A classic example of non linear systems are oil pipelines, tank filling operations, the sump pump in commercial buildings with underground water streams, etc.

Laplace transforms are indeed at the very root - pardon the pun - of electronic amplifiers.  Every audio power amplifier has a feedback loop to lower the output impedance and distortion and straighten out frequency response, etc.  Analog op amps nearly always have a feedback loop to control gain and bandwidth.  They are classic cases.

Digital amplifiers, quantifiers, converters and such things are usually inside a system loop of some kind.

In semiconductors the PLL (Phase Locked Loop - http://www.youtube.com/watch?v=SS7z8WsXPMk ) is an interesting little device widely used in control systems as well as electronics.

And so the story goes.  (And we didn't even get to positive feedback as opposed to negative feedback circuits!).

Best wishes.

Electrical Engineering

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#### cleggsan

##### Expertise

All technical areas of Electronics Engineering.

##### Experience

BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.

Organizations
IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.

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BSEE (Equiv) BYU BSEE University of North Dakota MSBA (MBA) Illinois State University Graduate Studies in Computer Science - Bradley University Graduate Studies - Ohio University Graduate Studies - University of Missouri Kansas City DeVry Tech - Electronics