Lecture 2: Analysis Methods and Rectifiers

MIT 6.622 Power Electronics, Spring 2023
Instructor: David Perreault
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In this lecture, we first review linear vs. switching regulators. We then introduce definitions and methods for analyzing switching circuits, including the Method of Assumed States and Periodic Steady State.
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[@ervivekchoubey]

Being an electrical engineer, it is refreshing to watch these lectures and an absolute gem helping me to fill the knowledge gaps that remain due to time constraints while taking the classes and exams. ❤

[@karolakkolo123]

Perfectly put, with the time constraints and exams sucking all time you could otherwise use to make projects and learn other useful stuff

[@lumpyfishgravy]

I trained in the late 1980s and we didn't get this level of *applied* engineering - mostly endless screeds of theory. What I use day to day is what I picked up and taught myself. And understand: I started work before The Internet. If there wasn't a book in the library, you didn't know it. I am loving this Playlist.

[@fabio.1]

👍👍

[@ttc2chan]

Me too😅

[@wthornton7346]

You took the words right out of my mouth!

[@veganath]

As much as i loved the 80's, freedom, privacy, music, near zero racism; education was orders of magnitude more difficult to source. Definitely looking forward to the day of AI directed private tutors....we're almost there

[@glenmerwyn5195]

Thank you for these lectures. I can't travel to a university (I'm geographically isolated) and need to study; I'm already a Mech eng, trying to study Electrical eng. Thanks (I live in NZ)

[@mboykin6047]

Wake up camera person. Show the projected illustration at the end.

[@jamescollier3]

They went on to film TED talks

[@ohsnapfit2096]

I think it just tracks humans..

[@empty_set_]

@@ohsnapfit2096 No ,they switched on the first example and then didn't on the rest.

[@bentpen2805]

Guess I gotta download LT Spice now

[@adrienferreira4666]

I watch Yale lectures and they never film the screen as well. Usually it’s for copyright purposes. There’s even disclaimers stating that some materials are protected and can’t be displayed. The university can pay authors to project their work in the classroom to the students, but don’t have the right to distribute it on KZbin.

[@alfonsocastellanosbalderas9842]

Thank you so much for sharing. Being an communications and electronics engineer, I am loving this video series.

[@SeniorScriptKitty]

i really appreciate the fact that this guy is using child style chalk

[@user-co6ww2cm9k]

Loving the ghost of a previous lecture on state machines in the chalkboard! It takes me right back to class!

[@MalyBa-ig2gi]

I am loving this shows ❤

[@RobertKennedyPersonal]

At <a href="#" class="seekto" data-time="2503">41:43</a> it's not completely clear what needs fixing. Vx has a discontinuity but it isn't clear why that's a problem because Vx isn't the voltage seen by the load. It seems like the inductor still protects the load from the ugly source-side voltage behavior. It would seem clearer to me if the problem statement here were accompanied by a plot of the load voltage and a clear statement of what problem needs to be addressed from that perspective. Or more broadly, a clearer statement of what the problem is, whether it has to do with the voltage seen at the load or not.

[@karolakkolo123]

There are many implied problems with it. First of all, it reduces your average voltage at the output unnecessarily. More importantly, because you can never precisely predict the *actual* value of L, it will decrease the output by an amount that isn't fully predictable. Another problem is that sharp changes in state like that will produce a ton of unwanted electromagnetic emissions from the circuit because of the high frequency content before the filter (this wastes some power too btw). Perhaps there are other problems I didn't think of as well

[@egertondidikallay9449]

Wonderful lecture ! Sadly we didn't get to see the simulations at the end. The Camera was too focused on the instructor.

[@byronwatkins2565]

At <a href="#" class="seekto" data-time="1260">21:00</a>, you drew the load voltage rather than the diode voltage. When Vin>0 the diode is shorted and Vd=I(0)=0. When Vin

[@Treepox]

In my mind... <a href="#" class="seekto" data-time="1300">21:40</a>. If Id is positive, the Vd is zero. That been said with an ideal diode. I think Vd is mixed up with Vo (Voltage over the resistor. Pleased to see reactions on my vision on this.

[@maxiandaur8509]

That's probably a little mistake

[@rafalklepinski7372]

Good, but feels like we missed something prof. Perreault was showing on the projector near the end..

[@therApist69]

It's paywalled : )

[@fabio.1]

​@@therApist69is there an online paid version of the course?

[@therApist69]

@@fabio.1yes but it’s well known to be hard to get in and costs quite a bit… might require a loan

[@fabio.1]

@@therApist69 👍

[@ayanahmed202]

You can download LTspice for free and simulate prof. Perreault's circuit. You can see everything you need to build the circuit at 48:36.

[@kikifaqih_]

thanks so much mit, thanks too for the subtiltle❤

[@tidin_tss]

very quickly and very briefly

[@raisingjakestudios1371]

Your pointing out of the inductance in the wall power source raises a question: What is the impedance of the Power Grid given there can be hundreds of miles of wire from generating station to home electrical outlet? More specifically, how many "grid tied" solar power converters can be attached to this grid before it becomes unstable?

[@SeanyKash8]

Greatly appreciated~

[@Tomty369]

Rewatch from <a href="#" class="seekto" data-time="2020">33:40</a>

[@mechadense]

<a href="#" class="seekto" data-time="300">5:00</a> start with new material

[@myronboone84]

<a href="#" class="seekto" data-time="3040">50:40</a> to <a href="#" class="seekto" data-time="3050">50:50</a> fault, default.

[@randydiffenderfer7793]

loving the availablility of these courses, as a retired quantum chemist, can see how the people who get their hands dirty do their stuff! also loving the "carbon copy" -- wonder how many students know where *that* came from? :D :D :D

[@campbellmorrison8540]

I wish I could go to MIT and really attend these lectures.

[@jamescollier3]

maybe a smaller school where you can ask a question, and not be on TV

[@campbellmorrison8540]

@@jamescollier3 Yes true, I really mean any University with these sort of courses and lecturers. Im now 70 and have done my dash unfortunately.

[@DHAVALPATEL-bp6hv]

@@campbellmorrison8540 no, you are not done, just keep moving .....

[@brucebuckeye]

ELI THE ICE MAN in action!

[@kayhanince]

ELI on ICE :)

[@Alexis-vg4pc]

Thanks for sharing

[@FooclesAutoRelay]

i love this

[@rich4239]

great series I am a noob and am confused at about 38 minutes the supply looks like a dc voltage but I think he is talking about AC...am I confused or is it just an oops by the prof

[@jnnewman90]

He is talking about AC at that time. The symbol for the source that he drew on the board is for DC, so it was his mistake. Everyone likely knew what he was talking about because he labeled the source as Vssin(wt) which implies that it is AC (sinusoidal).

[@user-fb5tz2mk5g]

Son un arsertijo entre dos puerta se vuelven x

[@jackevans2386]

Why has he not taken into account the 2 diodes' voltage drops of at least 0.6V each ?

[@josephthapa529]

It's an ideal diode assumption

[@misfitfarmandhomestead3057]

He's teaching theory in ideal conditions

[@Jptoutant]

I dont exactly get this ideal diode, why is it ON at 0V? isnt it at 2V more or less , or the only thing to consider in his explanation is infinite current capability at ON state.. the saturation point can be moved around

[@harishbharadwajp3600]

If it's 2V more or less, how is it an ideal diode? An ideal diode should not have any voltage drop across it

[@karolakkolo123]

Ideal diode model makes initial analysis easier. Real physical diodes obviously have a voltage drop and for typical current values the "on voltage" will be listed in the datasheet. You can modify analysis to account for that by having a voltage source instead of a short when the diode is on, etc. If you want to be even more exact, you can use the exponential diode equations and use some kind of iterative approach by guessing an initial voltage value and updating the state of other elements, which will generate a new voltage guess etc, but usually that's more work than necessary, and at that point you could as well just simulate it on the computer...

[@dahappychappy]

Maybe we should simulate it in LT Spice. To see for ourselves.

[@dominiquejones8831]

There we are. I'm late. Sorry

[@FreedomIsNotGoingToBeFree]

Should MIT use something from this century on the wall? I mean it is kind of scary how he is trying to hand draw things when you could have a huge screen with animated perfect examples... (which are reusable, re-viewable and asymmetric (eg. you can spend hours making them instead of minutes)).

[@tylerdurden9614]

what about lecture 3?

[@mitocw]

kzbin.info/www/bejne/iqHGZGx4q5iMgJo&pp=gAQBiAQB

[@kennethcfogarty]

Poor camera …

[@user-fb5tz2mk5g]

, es e s terminación po ase bale el sero

[@user-fb5tz2mk5g]

Es con kien dise pas o ira

[@denverbraughler3948]

MIT needs to standardize the titles of their videos. “Lecture 1” is a thoughtless name. The title needs course ID, year, lecture number, course name, and topic.

[@SakhiGuma687]

Imagine being so entitled that the most prestigious technical college in the world posts their class lectures for free and you complain about how they format their video titles.

[@tharun410]

​@@SakhiGuma687😂😂😂😂

[@bobross6228]

They do put some of that info in the description, but yeah a cursory title glance might not be so helpful

[@ervivekchoubey]

Exactly 😂 ​@@SakhiGuma687

[@WonderersWondering]

Brooo how much entitled are you.... Also you can get the whole course in a structured way on their website. If you please follow the link in the description

[@jan-pcro]

nice projection, i guess? 😂

[@user-fb5tz2mk5g]

V 12 vivo Jesus 5

[@QamruddinKhanlove]

CAN POSSIBLE TO CHANGED AUDIIO TO HINDI OR ANOTHER LANGUAGE ALSO

[@ervivekchoubey]

Click the captions button and select auto-translate to Hindi.

[@mckone9]

Camermannnnnnn

[@tidin_tss]

все очень кратко и очень быстро

[@veganath]

Please camera person keep the focus view on the content not the container(lecturer), the content is more important to the end goal of education than the container....

[@sattarpc]

Maybe I don't know but this diode state assumption discussion should be short and simple.

[@Danmaster01]

I was thinking that. He made a half wave rectifier sound like an intel processor

[@donmoore7785]

He is developing a method, using ideal diodes as an example. I like this approach.

[@rodrigoetoobe2536]

@@donmoore7785 the problem is that your predictions are bad, and you will try to build buck boost converter and fail miserably and wonder, why it blew up if I did the math correctly?

[@ervivekchoubey]

In high frequency power electronic converter​ of any kind, there are hundred other things that you need to take care of and you can't depend on math for them. For example, the generated Electromagnetic Interference from high switching which may interfere with other components or circuits and may cause problems or a ground fault or device thermal runaway. Only real projects can help us understand things. However we need to keep those things aside to focus on the working circuit to get the concept. @@rodrigoetoobe2536

[@07sanjeewakaru]

That's a general method for solving many diode system..

[@sdfasd8853]

Have you seen the video application for people who want to get to MIT? They already knew that. Seriously they are wasting money.

[@CutoutClips]

This is the second lecture of the course. It's important to establish a baseline of understanding before moving to more advanced topics.

[@benjaminrich9396]

The mic picks up the chalk scraping on the board in a way I find awful. I love these lectures but that scraping noise is killing me. Please buy some whiteboards!