If you’re a seasoned international rail traveler you will no doubt have become used to the various sounds of electric locomotives and multiple units as they start up. If you know anything about electronics you’ll probably have made the connection between the sounds and their associated motor control schemes, but unless you’re a railway engineer the chances are you’ll still be in the dark about just what’s going on. To throw light on the matter, [Z&F Railways] have a video explaining the various control schemes and the technologies behind them.
It’s made in Scotland, so the featured trains are largely British or in particular Scottish ones, but since the same systems can be found internationally it’s the sounds which matter rather than the trains themselves. Particularly interesting is the explanation of PWM versus pattern mode, the latter being a series of symmetrical pulses at different frequencies to create the same effect as PWM, but without relying on a single switching frequency as PWM does. This allows the controller to more efficiently match its drive to the AC frequency demanded by the motor at a particular speed, and is responsible for the “gear change” sound of many electric trains. We’re particularly taken by the sound of some German and Austrian locomotives (made by our corporate overlords Siemens, by coincidence) that step through the patterns in a musical scale.
Not for the first time we’re left wondering why electric vehicle manufacturers have considered fake internal combustion noises to make their cars sound sporty, when the sound of true electrical power is right there. The video is below the break.
I think this video is a boring ripoff of the much more interesting Beno’s video “Why do trains make interesting sounds”: https://www.youtube.com/watch?v=VOm8ePMg1dE
I followed your link, and I actually found the video presented in the article better. Beno’s video is dense in information, but misses real sound examples, skips on the variations in train sounds that Z&F Railway’s video presents, and contains some factual errors (GTOs are a type of thyristor, not a transistor).
That’s not to discount your video suggestion, just to add some more context for the next reader who might stumble upon it
That was a great video. Thanks for the link.
“Not for the first time we’re left wondering why electric vehicle manufacturers have considered fake internal combustion noises to make their cars sound sporty, when the sound of true electrical power is right there.”
Give it time – car culture evolves slowly. In due course, the sound of a transformer overload will be the “authentic” sound of macho motorsports replacing the current venting of nitrous through hood ports and the peculiarly tuned “hellcat” or “fart can” muffler systems .
The Siemens Taurus locomotives have an easter egg mode where certain musical themes can be programmed into the motor drivers. Here is one playing the Austrian national Anthem upon startup, https://www.youtube.com/watch?v=UkdQmDGU9AM, I have also seen some playing another musical piece (I think a Wagner) at standstill.
I suppose electric car manufacturers (or modders) will catch on to this trend and let cars make interesting sounds. Although I don’t really like the high-frequency wailing sound they usually make now – combined with the mandatory AVAS (Acoustic Vehicle Alerting System) which KIA implements as a very noticeable new wave synth sound…
this reminds me of a common hack used by some electronic speed control modules for small radio control brushless motors (like for model airplanes). it sends tones through the magnets, and you listen to the tones to navigate a menu system by turning the throttle on and off in a certain sequence. i think it’s pretty clever, though it’s tedious to use.
In Australia Hyundai calls it VESS – Virtual Engine Sound System – and I don’t think they could have picked a worse sound! It sounds like a whining hum with a musical overtone. It is absolutely terrible.
Fortunately ADR (Australian Design Rules) allow it to be turned off, but it defaults back to ‘on’ whenever you restart. I have a ‘button sequence’ when I get in to go, and VESS is the second button I press (to toggle it off). I believe some countries don’t allow it to be turned off (wire cutters anyone?).
The reasoning is sound (no pun intended) – to make persons close by aware the vehicle is “running” and not to walk in front. But they could have picked something better!
“The new Dodge Challenger HellEEEEcat, with authentic 20MW industrial motor startup sound and stepper motor shifts”
And the smell of hot rheostats!
The current reality is funnier than fiction – their current fake audio for their EV version is called the “frat”zonic chambered exhaust. Frat boy zone sounds about right, but I guess it could also be the fart zone, with a series of chamber pots. Oh, and they assure you, it’s made to be just as many decibels as the hellcat.
I’d rather an EV sounded like Eve from wall-e if it can’t just sound like whatever it actually is.
I’m reminded of the VW commercial where the car made sounds like George Jetson’s car.
I’d be so happy if I had an electric car that sounds like a ICE3.
They should let us customize the sound! Heck, they could even charge money and it would be like the ringtone market of the late 1990s…
Video doesn’t make it entirely clear, but on more recent trains are they using 3 phase motors, with the PWM’d signals being generated for each phase (the same way a VFD unit can take single phase mains AC and create 3 phase AC for 3 phase machinery, so long as the machinery in question isn’t hugely current-hungry), or is the IGBT generated PWM still being fed to the same type of single phase AC motor that trains had back before we had easily available high power solid state switches? Thanks
Why do electric trains hum? Because they don’t know the words. Thank you, try the veal.
Some of the trains here in Austria have actual musical notes as their ramp up PWM
Ok but how to hack it?
The reason why trains make sound is because they’re using relatively low switching frequencies at very high currents, so they have lots of harmonics in the audible frequency range.
The reason why electric cars don’t need to make any sound is because the switching frequency can be much higher for a smaller motor, and the harmonics caused are above the hearing range. If it’s going to make any audible sound at all – other than the mechanical noise of spinning bearings and rotors – it’s doing something wrong.
I’ve always wanted an explanation of the sounds made by the linear induction motor, Mark I trains of the Vancouver SkyTrain system. They almost sound like they’re changing gears as they accelerate out of the stations. The newer trains don’t make the same distinctive sound.
Induction motors may switch the pole configuration to change the operating speed range, so it is like changing gears in a sense, or, they may switch between delta and wye configuration to change the speed-torque characteristics of the motor as it approaches synchronous speed.