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.
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]
#12Some 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.
Re: How electric trains work and why they make interesting sounds [video]
#13As 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.
Re: How electric trains work and why they make interesting sounds [video]
#14Some 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.
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.
Re: How electric trains work and why they make interesting sounds [video]
#15Can't they filter out those sounds with some L's and C's?
Re: How electric trains work and why they make interesting sounds [video]
#16It'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.
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/
Apt example considering that they also released Microsoft Train Simulator in 2001.
Re: How electric trains work and why they make interesting sounds [video]
#17Can't they filter out those sounds with some L's and C's?
The motor is a bunch of big Ls, and the Cs are already used to feed the chopper.
Re: How electric trains work and why they make interesting sounds [video]
#18I 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.
Re: How electric trains work and why they make interesting sounds [video]
#19I 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.
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.