Preface

I am delighted to be presenting to you the new edition of my A to Z book, also known as “the red book.” It is a book that almost never was. I will explain why, and also share the reason it did finally make it into your hands today.

After my most recent writing effort in 2007, I was quite convinced I would never write a single word more on the subject. I stopped writing switching-power app notes, EE Times guest column articles, and so on, things I had revelled in the past. I became a wannabe Cat Stevens of sorts in the field of power conversion. Professionally, I moved on to quite a different ball-game, Power-over-Ethernet (which may even be the subject of my next book). Looking back however, perhaps the real reason for my self-imposed reclusiveness was that I was merely trying to avoid being crushed under the wheels of an oncoming freight train we all call “writer’s block” (sounds more like chopping block to me). Now I can finally confess, that in vague moments of nervous bravado past, I even secretly contemplated writing a novel instead, something original, perhaps like J.K. Rowling. I would actually make some money for a change (big money oh yeah, not chump change). But then I fell right out of bed. So coming back to the future, 4 years later, I am actually pleased to discover I have managed to add on almost another entire book on top of the existing A to Z book. Really, I couldn’t stop even after 9 months of rather grueling nonstop late-night and weekend writing sprees. I dreamt up vividly etched Mathcad programming loops emblazoned with Greek symbols in jaw-dropping high-definition quality (just a few years ago they were all in Technicolor, whatever happened?). Every now and then I had to be re-introduced to my wife and daughter, they tell me. One by the other, successively.

Meanwhile six, scratch that, eight new chapters were added. Keep in mind that the seven EMI chapters of the first edition are now four. But they are not condensed, just reorganized. These have actually been enhanced with better graphics and tables. In addition, several detailed design examples have now been thrown in, and old typos/errors hopefully removed.

Coming to magnetics, you will see that all the original equations on flyback core sizing that I had virtually pulled out of a hat in the first edition, yes, those very equations that had seemed so suspiciously simple, or perhaps just too good to be true (especially considering you couldn’t find them in any other book), are now all derived in Chapter 5. They were accurate all along, and that’s as much of a relief to me, the author, as perhaps to you. But there’s much more in Chapter 5, too, starting with the unique micro-joule-by-micro-joule energy transfer diagrams of the three topologies. I am pretty sure the process of power conversion has never been explained in related literature in so elemental, or fundamental, a manner. Yes, I really do like to cut to the chase. All the new material should go a long way in appeasing the magnetics skeptics in particular. But to be on the safe side, I have also presented all the equations and the original Mathcad worksheet, behind the AC resistance/proximity analysis charts I had previously published in Chapter 3 (though this time there is no accompanying Mathcad CD, only Mathcad-in-text). Air-gapped cores are also covered in a very simple manner in Chapter 5, using my unique “z-factor” treatment. I admit that particular idea came to my head years ago while talking to my mentor (and all-time hero of course), Doctor G.T. Murthy (now retired). As you may remember, I worked under him for 5 years in Mumbai (the first edition of that was called Bombay incidentally); and yes, Mumbai was also the undeclared city that formed the underlying inspiration for my well-known power conversion “train terminus analogy” on Page 1 of this book. Incidentally, I realized Chapter 1 had been so obviously liked by most readers that I did not have the heart to change it one bit, except perhaps to fix some graphics and minor typos. Chapters 2–4 were improved significantly, as were the old chapters titled “Conduction and Switching Losses” and “PCB Layout.” They were actually quite solid (and guaranteed to confuse if the need arose). But the perfectionist got hold of me here.

I have always felt that magnetics need not be as scary and challenging as some people make it out to be. But though I do want to simplify difficult subjects, I do not want to cut corners either and somehow pretend it is “oh-so-simple.” Because it really isn’t — nothing about power conversion is. We have all learned rather painfully over the years, never to judge a book by its cover, or a converter by its size (or its component count). Magnetics, in particular, can be so counterintuitive at times, we need to be on our guard always. The same holds true for loop stability: that is not so “easy” either, but with the right guidance, it can get much easier than you may have initially thought. I certainly don’t want young engineers thinking, as I did once, that the only way to understand this rather tricky area of power is to go out frantically geocaching in search of that exclusive invitation, the one that grants entry into a privileged club of experienced (and rather snooty) designers, who to the outsider, seem to be leading enviable lives in some mystical imaginary plane strewn with glittering poles and zeros. So, to make things even simpler than I did in the last edition, I rewrote, or rather reorganized, the entire chapter on loop stability. Then I fortified it with a detailed solved example contained in Chapter 19. I also added a new section on subharmonic instability and slope compensation, thereby acknowledging a rather glowing but constructive web review I had received on my previous book (you can still find that review on “Analogzone,” now “En-genius.net”).

In this process of restructuring the entire book to make all these substantial additions as seamless as possible (“no patchwork,” I had promised myself), and yet be thorough and simple at the same time (paradoxical I know), I did finally run into an obvious quandary. I wanted to maintain the oft-remarked readability of my previous book by not interposing very heavy equations and derivations throughout — I did not want to turn it into a scary textbook guaranteed to drive away all but the most captive EE students. I have always wanted my books to be used for real products, not just for good grades. On the other hand, I really did want to include all this extra new “heavy” material, for the more seasoned and demanding practitioners and professionals. So, I opted for a notable compromise: in the form of some rather busy-looking “wall-charts.” Initial impressions aside, and I will give you all the time to catch your breath here, the idea is actually quite simple: you, as a reader, can and should bypass these charts at first sight, assuming you don’t want to get into that much detail so early on in the game. The conclusions from these charts are well summarized in the accompanying text anyway. Later, when you are ready (or experienced enough in power) to get down and dirty, so to say, you can return to these very charts. And at that moment you will likely find all the additional information you need – available at your fingertips, in rather cramped but clearly demarcated pages that I call “wall-charts.” You can also use these pages as a quick reference, or cheat-sheet, going forward. In other words, I am hoping you will, not immediately, but eventually, love the idea — not only for what it did to the book, but also for what it didn’t do.

There are also some advanced and contemporary (emerging) topics included this time around: coupled inductors for example (Chapter 13). Unfortunately, these topics do need a good amount of mathematics and not much intuition can be brought to bear on them. So, feel free to skip them for now, but I think they are useful and very comprehensive going forward (I do not know of any power conversion book that distills these rather tricky topics for the average reader). I have based all my analyses on some scattered but excellent articles available on the IEEE Xplore website (IEL). Those sources have been duly acknowledged in the updated references of this edition. One time-consuming lesson for me while writing this particular chapter was to realize I shouldn’t accept at face value every single article or paper I came across on the subject, and I advise you to do the same to avoid needless confusion. I saw some papers/articles claiming everything on Planet Earth improved as a result of inductor coupling. But I know for sure that power conversion is, if anything, all about trade-offs and design compromises. As engineers, we almost instinctively expect to see both pros and cons listed out logically; two sides of the same coin. If not, I admit I tend to get worried that some potentially good engineering presentations from some fine corporations otherwise, were run past marketing first.

One long chapter, “Discovering New Topologies” (Chapter 9), has some really unique ideas, but I will let you judge its eventual worth. Is it a game-changer or is it not? Let me know. Same for the front-end of AC–DC power supplies (Chapter 14). See if you like that too. Authors always need to allow their readers to pass eventual judgment, even though a lot of work may have gone into a particular chapter. All I will ask of you is: these are tricky chapters, please don’t form an opinion after skimming through them just once.

Finally, time for some off-the-cuff observations: for example, you may have noticed that quite coincidentally, this edition too is largely red in color. I can therefore continue to refer to it in the same old-fashioned way. At my age, people quickly realize it is never a good idea to try and change habits; proposed changes habitually end up dead much faster by the roadside than habits. Ask my wife of two decades! So, I am just plain happy I can stick to calling this the “red one” and staying well within my comfort zone. But names aside, something has obviously changed drastically this time around: not just under the hood, but all around it, in fact maybe everything except the hood itself. Why? Well, this does happen to be the next edition of a previous book. And I believe getting to this point implies the earlier edition was a great success. So, for that milestone and achievement alone, besides my ever-supportive publishers, I really need to warmly thank my fantastic readers over the years. Especially those who, as complete strangers, took precious time off their busy schedules, either to write to me personally or post some really nice and obviously heart-felt 4- or 5-star reviews on the web (I am disregarding a couple of obvious trolls out there, for reasons known). However, I do need to apologize to some of you out there since I did not always manage to reply to your rather encouraging e-mails. But please be very clear about one thing: the only reason for the book you hold in your hands today is you. You made it happen. I got my writing spirit back largely because of you. Therefore, this book, in any shape, form, or color, would always remain my way of saying: thank you so much for your support and wishes in the past, and I hope you like this even more than the previous one.

—Sanjaya Maniktala

(Fremont, California)