[HN Gopher] How electric trains work and why they make interesti...
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How electric trains work and why they make interesting sounds
[video]
Author : zdw
Score : 103 points
Date : 2024-10-06 15:30 UTC (4 days ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| hejira wrote:
| Fun and educational video!
| CraigJPerry wrote:
| That video turned out way more interesting than I first thought.
| I never really considered why the 380 makes that noise, i assumed
| it was a maintenance issue.
| mlok wrote:
| It's a mystery to me how the camera is mounted for the video at
| 7:55.
|
| https://youtu.be/IRJIJPTUXXE?t=474
|
| A drone ?
|
| The camera follows the train so precisely that it seems it is
| mounted on the train, but it passes on the other side of some
| objects so it cannot be mounted on it.
| lainga wrote:
| I believe this is an example of ludonarrative dissonance. The
| camera is simply at a fixed offset from the train model.
| sicross wrote:
| That's not a real life video. Is a capture from a train
| simulator app.
|
| Like Microsoft Flight Simulator, but for trains.
|
| Example: https://www.trainsimworld.com/
| radiowave wrote:
| Your example is the exact answer.
| tshaddox wrote:
| Apt example considering that they also released Microsoft
| Train Simulator in 2001.
| mjamesaustin wrote:
| The secret behind this camera is that it exists within a
| virtual world, and therefore can freely float anywhere ;)
|
| An easier giveaway might be the floating teal icons on the
| station platform.
| zdw wrote:
| I think that's game footage, but not sure what game it is. The
| train game or sim genre has a bunch of folks who go incredibly
| deep and accurate in their representations of real trains.
|
| If you want an incredibly detailed 3 hour history of the genre:
| https://www.youtube.com/watch?v=5vwE_p9SCXw
| rootusrootus wrote:
| Simulations have gotten quite good, apparently. It threw me for
| a loop for a moment, too, until I figured out what was going
| on.
| jkingsman wrote:
| Fascinating video! One of my favorite train vids is a Taurus
| starting up in frigid conditions. As the wheels slip and the PWM
| modulation on the individual motors varies to keep traction, it
| makes beautiful music.
|
| https://www.youtube.com/watch?v=Q_bF1Wb_pSE
| asciii wrote:
| That's really neat - it sounds like a violin. I can barely keep
| a tune so I'm wondering if anyone knows anything special about
| the melody
| fotta wrote:
| Anyone know what the BART FOTF trains use? I'm guessing it's
| IGBTs but they sound more like fixed PWM switching to pattern
| mode with pulse drops.
| Animats wrote:
| Some OBB locomotives have their PWM systems tuned so that when
| they change frequency, they're always on a standard musical note.
| There's one example of that in the video. It's a cute feature,
| people like it, and it's probably all in software.
| 0_____0 wrote:
| They could easily have picked aharmonic intervals, and it would
| have even been a little easier. But given the opportunity, they
| chose to make something that added a little bit of color and
| magic to the world. I love that.
| theideaofcoffee wrote:
| As much as I love the futuristic and sophisticated sounds that
| electric traction drives make as compared to their fossil-fueled
| counterparts, I do think that the driving and control systems
| that actually generate the PWM waveforms that are sent to the
| motors are even more interesting. Huge, massive IGBTs weighing a
| kilo+ each chopping up hundreds of thousands of joules/s of
| energy without destroying themselves, current transformers,
| contactors, it really tickles parts of my brain. He only spent a
| handful of seconds on those, would be interesting to hear a
| deeper dive.
| itishappy wrote:
| Same! That stuff is so freakin' interesting! The other deep
| dive I really want (pun intended) is submarine sonar transducer
| drivers, which as I understand do basically the same thing but
| bidirectional and with a LOT more waveform customization.
| rwmj wrote:
| Photo on Wikipedia:
|
| https://en.wikipedia.org/wiki/Insulated-gate_bipolar_transis...
|
| Are they manufactured using regular silicon lithography? You'd
| think when making something so large you could just mix up the
| chemicals instead.
| theideaofcoffee wrote:
| From what I understand, mostly yes. They are still built up
| layer-by-layer with standard litho techniques, with pattern
| masks, ion implantation for the p- and n-type layers,
| etching, CVD to deposit insulation material (for the
| 'insulated gate' part of the device). Though they don't have
| to be nearly as precise, as I understand it as something more
| sophisticated, like a cpu, they still need to lean on those
| to make it chooch.
| bgnn wrote:
| I don't thik they're produced with the same process as CMOS,
| but I bet some photolithography is involved.
| 1970-01-01 wrote:
| Very early EVs (GM's EV1 and then a few other GMs) used banks
| and banks of water cooled IGBTs to spin the motor.
| amelius wrote:
| Can't they filter out those sounds with some L's and C's?
| CarVac wrote:
| The motor is a bunch of big Ls, and the Cs are already used to
| feed the chopper.
| amelius wrote:
| A class D amplifier + speaker has a very similar circuit
| topology, yet here we apply filtering all the time ...
| jimmaswell wrote:
| I still find it amusing that most fossil fuel trains only burn it
| to power a generator, with the wheels run by electric motors. It
| makes perfect sense with the massive startup torque a train
| requires, something electric motors are much better at.
| stackghost wrote:
| The term for that is a hybrid series powertrain. It allows one
| to optimize the generator to run at a single RPM, which leads
| to efficiency benefits.
| euroderf wrote:
| FWIW back in the 80s Mother Earth News had plans for a car
| that used this principle.
| Loughla wrote:
| I genuinely believe hybrid cars will be the path once we
| get the itch for electric cars out of our system. You get
| all the good parts of each engine type, with less of the
| bad parts of the other type.
| gambiting wrote:
| I have a PHEV and I genuienly believe this is the best
| combination of both, it's so practical with upsides of
| both drivetrains, but also let's not kid ourselves -
| PHEVs are vastly more complicated than either just plain
| ICE or EV cars, you have _a lot_ more stuff that can go
| wrong. I deal with it by just buying extended warranty
| for as long as they let me lol, but it 's definitely a
| concern with them.
| Lwerewolf wrote:
| The Prius and other HSD cars (i.e anything with a power-
| split device of the Toyota variety - input-split PSD) are
| some of, if not flat out the most reliable and simple ICE
| cars. Permanent atkinson-cycle engine, no turbos because
| there's no exhaust gas pressure to drive them in the
| first place (and if there was, it'd be an inefficiency to
| be rooted out), bulletproof starter/generator especially
| since the ls600h (double-sided cooling of IGBTs >> no
| usual IGBT packaging degradation-related failure modes -
| this was NOT the setup on the 3rd gen prius), still a
| very efficient power transfer from the engine to the
| wheels (a big percent is still transferred mechanically),
| etc, etc.
|
| Adding a bigger battery to those isn't a whole lot of
| increased complexity. The only issue is making a PHEV
| that has the same performance characteristics in both EV
| and hybrid mode - not that it hasn't been done.
| Specifically on HSD cars, the two electric motors
| combined, or even just MG2 (the "motor") have way more
| power than you'd assume - they actually function as an
| AC-AC converter, converting a significant portion of the
| engine's output power from mechanical to electric and
| back to mechanical again. It's essentially the way the
| eCVT works. Therefore, with a battery (and buck-boost
| converter) that can support such a load, they can propel
| the car alone way more than adequately - with a speed
| limit to protect the "generator" from too high RPM, due
| to the way the HSD works.
|
| Anyways, it absolutely can be done and it absolutely can
| be way simpler. If it's a case of a typical modern ICE
| with a big battery and a motor thrown in somewhere that
| makes it "hybrid"-ish - i.e. all the ICE complexity + the
| EV "complexity" (minus the classic starter/alternator) -
| yeah, no thanks.
|
| IMO: Good examples - the Chrysler Pacifica PHEV. Bad
| examples - C63 AMG (the PHEV version).
| rootusrootus wrote:
| What would you say the bad part is for a BEV?
|
| Personally I hope to never drive another gas-powered
| vehicle, hybrid or not. I'm very much addicted to the
| convenience and performance of modern BEVs.
| gambiting wrote:
| I drive across Europe few times a year and covering 800
| miles in one day is difficult to do in almost every BEV,
| maybe with the exception of Teslas. Also I had to deal
| with chargers in Germany a few times and it's been a pain
| every time(the classic - charger requires an account, the
| account only accepts german-registered payment card).
|
| But I'm also perfectly happy to admit that it's fine and
| doable just requires adjustment of expectations, and even
| the charging network thing I'm sure has solutions if you
| plan beforehand.
| spockz wrote:
| I got the tip from other BEV users for charging in
| Germany to go off the highway and find something like a
| shopping center/mall. There they had always plenty fast
| chargers and something convenient to do as well. Their
| built in navigation showed them the way. (This was bmw,
| not Tesla.)
| thatfrenchguy wrote:
| I mean, you can use Tesla chargers with any car these
| days in the EU?
| rootusrootus wrote:
| I hear you. This is a choice everyone has to make for
| themselves. Not everyone will have the same priorities or
| circumstances.
|
| My longest yearly trip is ~1200km, but that's like once a
| year. Several times a year I do a 500km trip. On the long
| haul the additional refueling stops make the trip about
| 10% longer, on the shorter trip it has more impact, about
| 15%. Caveat: this is in the western US and superchargers
| are invariably right next to the freeway, so they don't
| add much time to the trip.
|
| What really sold it for me was eliminating the trips to
| the gas station. That is a level of convenience it will
| be hard to give up.
|
| I'm in the market right now for a new second vehicle,
| since I'm eliminating the need for a thirsty HD pickup
| capable of towing our trailer, and what I'm finding is
| that the market for EVs is not great in the truck space.
| Couple choices, both with ups and downs, and a little
| bigger than what I'd prefer (C'mon, Toyota, make us an
| electric Tacoma). So I'm faced with having to get another
| ICE vehicle, and the inability to fuel at home bums me
| out.
| elihu wrote:
| Continuing to burn fossil fuels forever isn't really an
| option. At some point we'll effectively run out, but
| before then we'll have caused catastrophic climate change
| due to our CO2 emissions.
|
| Synthetic or plant-based fuels are plausible options, but
| synthetic fuels can't compare with battery EVs in terms
| of energy efficiency, and plant based fuels need crop
| land that's probably better used to grow food.
|
| Electric vehicles aren't a temporary fad. They're here to
| stay. Liquid fuels aren't going away either, but I expect
| eventually they'll be used mostly for military and
| aviation applications, not ground transportation.
| rsynnott wrote:
| Some buses also use these. Dublin Bus has a particularly
| disconcerting plugin hybrid variety; if it's using the diesel
| engine, that runs constantly (so it's noisier than a normal
| bus at rest) but if on battery, it's silent. There are few
| things more unnerving than a double decker bus gliding along
| virtually noiselessly (their pure-electric buses, somehow,
| are noisier). Double-decker buses are supposed to sound like
| they might explode at any moment, like in the good old days.
|
| (/s, just in case; ye olde 20 tonne 1980s buses were
| extremely noisy, and it was not great.)
| drmpeg wrote:
| The other problem it solves is the complex transmission
| required. Diesel-Hydraulic locomotives were built, but were
| not successful long term. The most famous is the Krauss-
| Maffei ML4000, built for the Southern Pacific railroad.
|
| https://en.wikipedia.org/wiki/Krauss-Maffei_ML_4000
| rootusrootus wrote:
| Great video, lots of nice details. Now I wonder what technology
| our local light rail train is using, because I've noticed the
| gear switch sound (though it just has a single switch at perhaps
| 10-15 mph or so). Apparently it's a Siemens S70 (there are
| several varieties of rolling stock, but this is the one that
| makes the most distinctive sounds).
| exabrial wrote:
| I do not have perfect pitch (cool party trick), but I can
| identify all 8 'normal' equal temperament intervals by ear
| relative to a reference (If you couldn't guess, I play bass,
| which is a lame party trick).
|
| I was in Austria last year, and a bunch of the trains starting
| from a standstill had a "gradual acceleration" algorithm for
| their traction motors. As the drive frequency increased, you
| could hear the drive motor whine (or maybe it was the inverter?)
| along with the frequency. It was fascinating, because it played
| chords as it accelerated: root, 2nd minor, 4th major, 6th minor,
| octave, then it would pause at the octave and do it again after a
| few seconds until it reached max power I assume. Each chord had a
| very faint tritone added to it relative to the chord tonic, so
| you got this really harmonic pulsing.
|
| After the second course there was too much rail noise to hear
| what happened, but it was fascinating. I'll try to find a video,
| I know I recorded it.
|
| Power in Austria/Germany is delivered to trains via a really
| weird standard too: something like 25hz 27 kV. Leftover standard
| from 100 years ago.
| the_mitsuhiko wrote:
| Normally it just plays the scale:
| https://www.youtube.com/watch?v=-SDYdHzT7Qw
|
| But it can be configured to play other tunes. Here is a rare
| recording of it playing the Austrian anthem:
| https://www.youtube.com/watch?v=UkdQmDGU9AM (another recording:
| https://www.facebook.com/unsereOEBB/videos/290883783832057/)
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