A previous video has discussed the RC Snubber. This video discusses adding a diode to an RC snubber for a turn-off snubber, adding a diode to a LC snubber for a turn-on snubber, and combining capacitors, resistors, inductors, and diodes in combination snubbers.
Rudy Severns, author of Snubber Circuits for Power for Power Electronics, talks on video about the importance of the resistor-capacitor-inductor-diode snubber described in Chapter 4, Dissipative RCL-diode Snubbers, of his book
You may not have the bandwidth to see the video, so a much shorter audio file and a transcript are provided.
Video - RCL Diode Snubber
(3:09)
Audio - RCL Diode Snubber
Listen to the audio of RCL Diode Snubber (408 kB)
Transcript - RCL Diode Snubber
Introduction
Hello, I'm Rudy Severns, welcome to my office. I'm writing a book on the design of snubber circuits for power electronics. In fact, the book's 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 can get a really good feel for what this book is all about.
RCL Diode Snubber
Now we've talked a little bit about passive snubbers, just simple RC damping networks. These are very useful and very popular, but very, very often that's not enough. You can't do everything with a simple RC snubber.
What happens is if you add a diode to the network you can then do more, more types of snubbing and control of the losses in the switch. So the next class of snubbers, and again we have devoted an entire chapter to it, will be called RCRL Diode Snubbers. In other words, they include capacitors, inductors, resistors, and diodes.
These are generally dissipative snubbers. Now, that doesn't mean that all the energy that's saved in the switching, because the snubbers will actually reduce the switch loss, but not all of that power needs to be dissipated, but generally speaking, you'd only save maybe ten or 20%. So a well-designed RCD snubber will actually improve the overall efficiency, but not by a large amount.
It should sort of be a little icing on the cake, just help you out a bit. But what it does for the performance of the switch and the reduction of switch stress is what's so very important about this family of circuits. And again, what we'll do is we'll approach it by, first of all, talking about turn-on snubbers. In other words, a snubber that's effective as you turn on the switch and reduces the stress in the switch at turn on.
Then we'll talk about turn-off snubbers. In other words, snubbers that operate when the switch is turning off. Finally, we'll talk about many different kinds of combination snubbers. In other words, these are snubbers which are working both at turn on and at turn off. We'll find that there are some very interesting optimization problems that have to be solved there.
In fact, some of the most popular of the turn-on, turn-off combination snubbers, the very most popular one cannot actually be optimized at both ends, it's always a compromise. So you end up with a trade-off. That particular trade-off will be treated carefully in this chapter.
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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