How electric trains work and why they make interesting sounds [video]
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> Google translation: When switching on from a standing start, a noise can be heard that is reminiscent of playing through a scale on a tenor saxophone. It is created in the three-phase motors by controlling the power converters. The noise is twice the clock frequency of the pulse inverters, which is gradually increased. The frequency changes in whole and semitone steps over two octaves from d to d" in the tone pool of the root tones. It is a Dorian scale on the root D. Theoretically, it would be possible to program the locomotive in such a way that it emits completely different sounds. However, the manufacturer has opted for a scale because these sounds are perceived as pleasant by the human ear. This makes it possible for a four-voice tone to result when the wheelsets are spinning (for example due to wet rails).
No wonder the Austrians (who have a reputation of being music lovers) have most of these engines...
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.
Here's a data sheet for a somewhat larger one.[1] The control signal is only 6 volts at 5 mA. It's incredible that this is physically possible.
[1] https://www.infineon.com/dgdl/Infineon-FZ1500R45KL3_B5-DataS...
(silicon lithography is more of a broad range of processes: digital vs analog vs power vs MEMS all have very different needs, and so a process designed for one will look very different to another, and one designed to allow multiple will be making compromises)
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.
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/)
Just compared it to a midi player... first video starts on a G. It may not be equal temperament? Some of the scale degrees sound just slightly flat or sharp.
The German standard you are thinking of is 15kv 16.7Hz.
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.
Like Microsoft Flight Simulator, but for trains.
Example: https://www.trainsimworld.com/
An easier giveaway might be the floating teal icons on the station platform.
If you want an incredibly detailed 3 hour history of the genre: https://www.youtube.com/watch?v=5vwE_p9SCXw
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).
I was told this is not true for 2006 Alphard hybrid (I have one). ~USD1000 part (usually old Toyotas have cheaper parts).
And beware that older hybrids use small (e.g. 50Wh) NiMH batteries - I think they started to change to Lithium in 2017 or something
https://toyota-club.net/files/faq/21-11-20_faq_hybrid_thsc_e...
"Hybrid repair experts have called the first generation Estima (AHR10) Toyota's most problematic hybrid vehicle ever."
OTOH, one of the last times I rented a car, they 'upgraded' me to a PHEV, and I wasn't impressed. It was a tight fit with the kids + luggage, and we didn't even have the dog along. Fuel economy was well worse than plain old diesel, because it turns out when they give you a PHEV with 0km in the battery, it's not much of a hybrid. (This was a Volvo S60).
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.
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.
I have no idea why they don't just use the kind of dumb payment terminals every unmanned carbohydrate station uses. Works with any card from any country all the time.
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.
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.
This is almost meaningless. If you are turning renewable energy sources into either synthetic fuel or grid power, then efficiency is irrelevant. What matters is cost (of the whole system, including distribution of the energy) and emissions (burning even carbon-neutral methane or hydrogen isn’t quite zero emission). There are startups working synthesizing fuels from air and solar energy, and they argue, fairly convincingly, that bypassing the entire electrical distribution network can more than make up for extremely low efficiency.
Also, heavier vehicles likely emit more brake and tire dust than lighter vehicles, and a series hybrid can be much lighter than a long range BEV.
Burning liquid fuel in a heat engine typically wastes about 2/3 of the chemical energy as heat. Hybrids do better, but there's only so much you can do.
I don't know what the state of the art for synthesizing liquid fuel is, but I assume there's some significant energy loss there too.
On the other hand, modern permanent-magnet electric motors can be around 95% efficient. Lithium ion batteries typically have coulombic efficiency better than 99%. Actual energy efficiency is a little less due to internal resistance (it takes a higher voltage to charge the battery than you get out when you drain it, so even if amp-hours in is almost equal to amp-hours out, watt hours might be a little different). Charging circuitry also tends to be pretty efficient. Battery-electric drive trains are already so close to optimal efficiency that there's very little that they can actually be improved on, and nothing else comes close.
The tire dust microplastics thing is a real problem, but it's not that much worse for EVs than other cars. Brake dust is much less of an issue on BEVs and hybrids, due to regenerative braking.
Personally I hope the idea of BEVs that haul around 800 pound batteries goes out of fashion (and it might if we could be bothered to electrify our major highways to make huge batteries largely unnecessary), and I also hope cars in general start to get smaller and less numerous. But I think cars are basically here to stay in some form, so they might as well be electric.
(/s, just in case; ye olde 20 tonne 1980s buses were extremely noisy, and it was not great.)
VFD AC motors will intrinsically self-correct for overspeed when static traction slips and starts going into dynamic region (due to the frequency being slower than the slip/overspeed) and re-enter static friction region. DC or ICE will react to the lack of traction by turning faster as you hit the dynamic friction region and "spin out". Traction control is always reactive and lags behind. Last I read the difference in traction on rail for AC vs DC was on the order of 50%(!).
It's also why EV cars have stupidly awesome traction in adverse conditions under acceleration, trains had been perfecting that technology for decades.
That also makes fully electrifying these things less off a technical challenge and more of a battery cost challenge. Mostly size and battery density isn't that big of a deal even. There's plenty of room in a large heavy vehicle to put some batteries. Even if they weigh a few tons it's not necessarily that big of a deal. Except of course if you need to go half way across the globe with a ship. But shorter range of up to 100-200 nautical miles if very doable now. A big mining truck has plenty of space and they are big and heavy anyway.
To me, the example of the PWM wave [1] looks like the VFD mode, but:
- instead of varying between [-V..V], varying between [0..V]
- instead of having a regular variation of pulse pattern to get a regular wave, having an irregular pattern.
But that irregular pattern (or non-recurring pattern) only seems to be an illustrative example to match the brown wave shape, and I assume you wouldn't want to have irregular wave patterns to drive your engine?
Btw nothing beats the sounds made by both steam- and opposing-piston diesel engines - you can feel the power. Sounds made by electric engines are mostly whining.