Designing Control Loops for Linear and Switching Power Supplies

Designing Control Loops for Linear and Switching Power Supplies pdf

Control Loops – Loop control is an essential area of electronics engineering that today’s professionals need to master. Rather than delving into extensive theory, this practical book focuses on what you really need to know for compensating or stabilizing a given control system. You can turn instantly to practical sections with numerous design examples and ready-made formulas to help you with your projects in the field.

You also find coverage of the underpinnings and principles of control loops so you can gain a more complete understanding of the material. This authoritative volume explains how to conduct analysis of control systems and provides extensive details on practical compensators. It helps you measure your system, showing how to verify if a prototype is stable and features enough design margin. Moreover, you learn how to secure high-volume production by bench-verified safety margins.

Book Review by JLK

Finally! A comprehensive explanation of power control in easy to understand language!

Here’s the short review:
If you are new to power electronics and control systems, then this is the book for you. Everything, starting with the basics, is explained in easy to understand language. If you are very experienced with power controls, then this is also the book for you. The book covers everything and probably has a few tips and tricks that you haven’t seen before.

Here’s the longer review:
I’ve been doing power electronics professionally for nearly 15 years. And the most difficult (and mysterious) part of it has always been loop control. I don’t know why this is, but it is a common source of confusion among power circuit designers. Most of us learn from white papers, app notes, IC tutorials, etc. Its a very convoluted way to learn though–everyone has a slightly different take on the topic, and it just gets confusing. There are textbooks which cover some of this material. But they tend to fall into one of 3 categories. They are either rather simplistic (they only apply to a few easy situations), or full endless equations and derivations (their point gets lost), or they only include the author’s “preferred” method for stabilizing power systems (and so they ignore the fundamentals).

Enter now Christophe Basso’s 3rd book: “Designing Control Loops for Linear and Switching Power Supplies.” (The other 2 books, particularly the “Switch Mode Power Supplies”, are excellent also.) I’m sure you can find the table of contents online, so I won’t repeat it here. There are 9 chapters that break the book up into basically 3 parts:
1. Fundamentals of Control (which I could also title: “things I forgot from college” or “things I ‘should’ know and so I’m embarrassed to ask my coworkers about”). These chapters are fantastic. All the control theory, transforms, etc. are presented in a sensible way. It takes a lot of the mystery out of understanding power control. And Basso has a very natural style of writing that puts all the material in easy to understand language–but without dumbing down the principles.
2. Op amp topologies and stabilization techniques. This also includes the most popular, and least discussed ones–the transconductance amp and the TL431.
3. How to measure and verify the loop design. Very few authors write about this, but it is one of the most important aspects to control loop design. Basso answers the why, where and how of verifying and correcting the loop design.

Each chapter also includes examples and simulation models.

A book like this is long overdue for the power electronics community. I’m convinced it will be one of the must have books for every power designer to have in their library.

Review

Mr. Dennis Feucht from Innovatia Laboratories published a review of thebook in the online power electronics newsletter How2Power.com: 

how2power.com/newsletters/1304/H2PToday1304_bookreview_DennisFeucht.pdf

From the Author

When I started writing this book, my goal was to teach readers how tobuild compensation structures using various types of active elements.Actually, most of the textbooks that I owned only disclosed compensation structures using operational amplifiers. In our industry, there areother active elements that can be implemented in compensators: TL431,transconductance amplifiers (OTA) and shunt regulators. I have dedicated chapters to all of these devices, including the effects of theoptocoupler in the case of isolated converters.


When these chapterswere over, I decided to add theoretical information on loop control. How to tackle the subject without reproducing what already exists in goodtextbooks? The main idea was to narrow down the text content to what anengineer should really know for his daily job. Indeed, the world ofcontrol systems is wide and you don’t need to know everything for yourengineering tasks. The main idea of this book is to bridge theoreticalknowledge to practical reality: derive equations and put them at work in design examples. Where phase and gain margins come from, what is delaymargin, how do I link PID coefficients to poles/zeros placements and soon.

As usual, I derived all equations including intermediate steps sothat you can easily follow the flow. The book uses power electronicsexamples but theory can be equally learned and applied to otherengineering fields.
This book is not a substitute to classicaltextbooks but it can be seen as a design companion for the engineer andas a class complement for the student. Both look for a bridge betweenwhat they have learned at university and the engineering world reality. I modestly hope this book will fulfill that goal.

Christophe P. Basso
Toulouse, 2012
cbasso.pagesperso-orange.fr/Spice.htm


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