The discussion of RC Snubbers, RCLD Snubbers and Energy Recovery Snubbers in previous videos provide, in a natural progression, the insights necessary to master snubber design.

This video discusses the circuit analysis techniques for analyzing snubber circuits using the energy recovery snubber as an example. The energy recovery snubber is sometimes inexactly called a lossless snubber. The video is of special interest since it gives an insight of how a world-class circuit designer practices his craft -- something that is hard to convey except in a video or by one-on-one mentoring.

You may not have the bandwidth to see the video, so a much shorter audio file and a transcript are provided.

Video - Energy Recovery Snubber Analysis

(3:15)

Audio - Energy Recovery Snubber Analysis

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Transcript - Energy Recovery Snubber Analysis

Introduction

Hello. I'm Rudy Severns and welcome to my office. I'm writing a book on the design of snubber circuits for power electronics. As a matter of fact the books title will be Snubber Circuits for Power Electronics.

What I'd like to do now is to share with you the contents of one of the chapters so you get a really good feeling for what this book is all about.

Energy Recovery Snubber Analysis

What we have is a very simple inductor, capacitor, diode, snubber -- a very common circuit, widely used. In the dissipated version of this, normally you'll have a resistor, which goes from this point up to this point. That's a power dissipater.

What we've done is we've replaced that resistor with two diodes and a capacitor which allows us to dump the energy into the output, in this case the output load so that the energy is recycled instead of being burned up.

You would think it's a very simple circuit. We've taken out a resistor. We've added two diodes and a capacitor in their place. Well it turns out that it becomes a very, very interesting design problem to understand how this circuit works. This is rather common amongst these energy recoveries.

The first thing we do is go out over here and put down the voltage and current waveforms for each of the time intervals, all 13 of the time intervals, in order to make sense of how the circuit works and what all these wave forms actually mean. What's necessary is to actually create a small circuit drawing which represents the active components during each time interval. As we see over here we have 13 time intervals, so we need 13 drawings.

Here's a set of sketches, one after the other, all the way through, until you've completed one full switching cycle and you're ready to start again. Of course, you need some additional information like initial conditions and so forth -- the voltage on capacitors and currents in inductors and that sort of thing.

What we'll do in the book to explain how this circuit works and of course to explain how to design the circuit is that we'll actually go through and use each one of these little sketches to explain how the circuit is actually performing or working during that particular time interval.

By going through the full sequence you'll be able to see exactly how this circuit works and hopefully be able to design it. All that information is part of chapter five. This is one example that will be included in there.

Rudy Severns' book "Snubber Circuits for Power Electronics" is available for purchase on the Internet as an ebook in PDF format. More about the snubber ebook.



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