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How electric trains work and why they make interesting sounds [video]

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Re: How electric trains work and why they make interesting sounds [video]

#71

Post by 0_____0 »

leoedin wrote: post #61
Animats wrote: post #58

Earlier quoted context omitted.

It's amazing how small those things are. That's a transistor which can switch four megawatts . A manual switch with the same rating is bigger. 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...

As an embedded engineer sometimes working on PWM, it's interesting to think that the origin of the gate drive signals is still just some sort of microcontroller timer running at 3.3V and a few mA. I'm sure there's a few layers of level translation and isolation between the micro and the 4 MW power transistor - but it's still indistinguishable at the digital level from a circuit driving a tiny motor on my desk.

An ant driving an M1 Abrams main battle tank.

Re: How electric trains work and why they make interesting sounds [video]

#72

Post by gambiting »

wiredfool wrote: post #70
gambiting wrote: post #24

Earlier quoted context omitted.

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.

I think a PHEV would be ideal for me -- Bimodal use, mostly a few km trips, and then a few 1000km trips/yr. The long trips are the ones where we wind up filling the car, so space inside/towing is important. (We've got a 7 seater, used to be a renault grand scenic, now a ford galaxy). 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 + lu…

Ours is an XC60 T8 and yeah, I do 90% of my day to day driving in EV mode, then few very long distance trips on fuel. But yeah, not much use if it's not charged.

Re: How electric trains work and why they make interesting sounds [video]

#73

Post by fransje26 »

Could someone explain the difference between the PWM mode and the pattern mode?

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?

[1] https://youtu.be/IRJIJPTUXXE?feature=shared&t=406

Re: How electric trains work and why they make interesting sounds [video]

#75

Post by atahanacar »

fransje26 wrote: post #73

Could someone explain the difference between the PWM mode and the pattern mode? 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 mat…

As far as I can understand from the video, pattern is variable frequency PWM.

Re: How electric trains work and why they make interesting sounds [video]

#76

Post by fransje26 »

atahanacar wrote: post #75
fransje26 wrote: post #73

Could someone explain the difference between the PWM mode and the pattern mode? 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 mat…

As far as I can understand from the video, pattern is variable frequency PWM.

So a PWM pattern with a fixed number of pulses that are relatively broadened/shrunk to have a variable wave frequency?

Re: How electric trains work and why they make interesting sounds [video]

#77

Post by namibj »

rcxdude wrote: post #63
rwmj wrote: post #27

Earlier quoted context omitted.

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.

It's definitely lithography on silicon wafers, but a lot of the details are very different. For example, it's pretty common for power devices to be manufactured to be formed from the full thickness of the wafer, as opposed to just on the surface. And a single device tends to be formed of many repeating blocks, since you do need fine details still to get the performance (And a lot of the challenge is making sure each…

The "full thickness" aspect is commonly called "vertical" when talking about the devices.

Re: How electric trains work and why they make interesting sounds [video]

#78

Post by CarVac »

robocat wrote: post #49
Lwerewolf wrote: post #37

Earlier quoted context omitted.

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 (doubl…

> bulletproof starter 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

The Alphard hybrid had a belt CVT, rather than a power-split-device hybrid.

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."

Re: How electric trains work and why they make interesting sounds [video]

#79

Post by asciii »

rob74 wrote: post #59
asciii wrote: post #30

Earlier quoted context omitted.

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

Detailed explanation (in German) here: https://de.wikipedia.org/wiki/Siemens_ES64U2#Ger%C3%A4uschen... > 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 incre…

Wow! I love HN for these finds, thank you
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