Article on capacitors. Does this ring true?

[watchmaker]

https://finance.yahoo.com/news/why-humble-capacitor-electric-car-180000660.html

[David Hess]

Yes, as the power density of traction inverters increases, the DC link capacitor becomes the limiting factor.  They operate close to their maximum limits.

High-Energy Density Capacitors for Electric Vehicle Traction Inverters:

https://www.osti.gov/servlets/purl/1649202

[coppercone2]

 "stubbornly analog" , I guess you can't expect more from finance cave men

who the HELL writes that garbage

is the battery digital to him ? or the motor? what are those doing running in a excel box? and whats stubborn about it?


I stopped reading yahoo in the last 6 months because it feels like everything there is spit out of a AI text generator

the article says "the car industry is having trouble developing some electrical component and here is some word salad to go with that notice"


Seriously with the stuff yahoo dredges up, I am starting to feel like there was more to actually read on it 20+ years ago. is it supposed to make me feel that capacitors are some how bad? Does he also have a vendetta against water towers?

[ejeffrey]

It's not exactly wrong, but it's kind of just describing how engineering works:

The result is a collision between the marketing department's desire for "fast charging" and the engineering department's struggle with "thermal runaway."

Yeah, you have to optimize your design.  Cost, size, efficiency, charging speed, reliability are all tradeoffs. That's how this works.

[coppercone2]

materials science is not where we want it, get angry about it with us at 11

i feel like im going to get bitched out because of the dielectric properties of polypropylene by some accountant now, and ferrite is too heavy, and chips are too expensive

Why do I think that the article is trying to make me feel "outraged" by electronics... maybe I am getting paranoid but I think it might have something to do with "oilprice.com"

I was just thinking about how stubbornly analog a combustion motor is lol

[David Hess]

Why can't you use these polyester capacitors?  They are much less expensive, and smaller.

[TimFox]

Polyester has roughly 10x higher dielectric loss than polypropylene.

[David Hess]

Polyester has roughly 10x higher dielectric loss than polypropylene.

I was mocking management and marketing.

[jonpaul]

Article is fine.

Indeed power  PFC and bus caps can be  critical, but the foils and dielectrics are plentiful.

Real choke point is silicon steel  lamination, and tapes and ferrite cores.

100 kW - 1000 MW  utility transformers are on BO 1-8 years and custom made.


Thus after storms, sabotage or incidents at generation and substations, the damages may be unrepaired until the transformers are available.

Never see this in capacitors yet.

Jon

(EE for over  half century)

[Geoff-AU]

Article is fine.

+1.  Reading between the journalese hyperbole the author knows a bit.  Sadly, that's just how you have to tell stories to generate clicks these days.  It's a good education campaign.

[coppercone2]

That is saying something when you need to make a something out to be like a bad guy to get someone to read it. You would think there is more then enough of that in politics and that economy/science could be.. .educational... when its like in a serious publication like a paper that belongs to a professional organization

Maybe that is how you get people stuck in the celebrity/politics/criminal sections to read something else. The conditioned brains are just losing traction when its just plain information...


yahoo news makes me feel like I am reading old daytime television (before the fall of television). That is something people used to learn, don't turn on the TV before like 4pm if you happen to get stuck indoors in the not so recent past, and you will have a happy life. jerry jerry jerry jerry.... 

maybe I just read too many murder mystery articles about which vegetable is actually a killer (yahoo said its iceberg lettuce, I think its innocent, despite not having the stunning alibi's that romaine has)

[tom66]

I don't think anyone making an 800V inverter is switching the transistors in nanoseconds.  This would create ludicrous EMI problems that the best capacitor wouldn't be able to solve. Soft switching is a trade off, slightly worse efficiency but lower dV/dt.  And the ICCU failures are not caused by failure of the link capacitor, but seem to be due to water getting into the units because of a sealing/breather vent fault.

[David Hess]

I don't think anyone making an 800V inverter is switching the transistors in nanoseconds.  This would create ludicrous EMI problems that the best capacitor wouldn't be able to solve. Soft switching is a trade off, slightly worse efficiency but lower dV/dt.  And the ICCU failures are not caused by failure of the link capacitor, but seem to be due to water getting into the units because of a sealing/breather vent fault.

I assumed they are referring to the transition from IGBT to SiC and then GaN MOSFETs, so not literally nanosecond switching, but much faster than the previous technology.

[Cyclotron]

I think I might be the only one who can't stop laughing about the subject line.

[tom66]

I think I might be the only one who can't stop laughing about the subject line.

It's a real tank of a joke.  I wonder if they can induct us on other phases of the problem?   

[Siwastaja]

I don't think anyone making an 800V inverter is switching the transistors in nanoseconds.  This would create ludicrous EMI problems that the best capacitor wouldn't be able to solve. Soft switching is a trade off, slightly worse efficiency but lower dV/dt.  And the ICCU failures are not caused by failure of the link capacitor, but seem to be due to water getting into the units because of a sealing/breather vent fault.

Yes. The article is full of totally made-up stuff. Like, written by someone who has a surprisingly wide, but not deep enough knowledge, and fills in gaps (lack of technical detail) with hallucinating up something which sounds convincing. I have seen worse articles, of course, and have no problem with the flashy / clickbaity style, but it has simply too many incorrect / made up details... Can't trust anything by that author, really.

[temperance]

Interesting how a few people here are thinking those caps have something to do with nanosecond switching of whichever switch in there or the input of the PFC. (You don't want capacitors at the input of the PFC at all. Just the bare minimum to cope with HF decoupling and filtering. Filter= hint as to why not.)

Here is an idea: what happens during the dead time of the motor drive? Where does the energy stored in the cables feeding the motor drive goes to?

Those capacitors are specifically made to be placed across each bridge with the lowest stray inductance possible. This can be seen in some teardowns of such drives on YT.