The Siemens Taurus locomotives make the absolutely best sound of all trains. It literally plays a musical scale while accelerating from a stop. There are countless videos of it on RUclips.
@@AegisEdge You might not have checked what a Taurus is. The ES64U2 also has SIEMENS GTO modules like the 京急1000 and 2100 series, they also feature the musical scale during the asynchronous phase, and imo the scale sounds better on the Taurus. Not disregarding the 京急 trains tho, i love them and it’s sad to see them replaced with new IGBT modules. These singing Tauruses are still pretty common in Europe, here’s a video of a Taurus accelerating on its own fyi :) ruclips.net/video/vxOUdp903UE/видео.htmlsi=mNtRQo7TeombXyTl
I always felt that a train’s motor sounds made up a part of its “identity”, and I also kinda wondered how the sounds are made. I know part of it is due to electromagnetically-induced noise (coil whine), but I always wondered why even the same type of motors might sound different when they are from different manufacturers, etc. This video definitely provides a good overview of what I always wanted to know.
This is a brilliant video! I was always wondering why electric trains make that sound! I personally love motor noise. My favourite motor noise comes from the Siemens Taurus, Class 455, Class 323 and Desiro.
The synchronous (pattern based) mode is used to reduce motor current harmonics. The method is called "Selective Harmonic Eliminated PWM" or just "SHEPWM". And you are right, the transition between patterns is because of the limited maximum switching frequency - very well explained! For asynchronous carrier based modulation there are many methods. More common nowadays is the Space Vector Modulation (because it creates less current harmonics) and in older drives you would find 'center-aligned' or 'edge-aligned' SPWM methods. All of these carrier based modulation methods can be used with a random generated carrier in a given range to reduce harmonics even further.
You mean pattern based, in contrast to a hard square wave, right? The closer you get to a proper sine wave, the less other sine frequencies you are going to have in the final motor drive frequency. Or do you mean you are making sure the pulse signal sent to the thyristors doesn't have any components above a certain frequency - the elimination of the too thin pulses as explained in the video?
6:00 Those DC motors sound so beautiful. Outdated technology? Yes. But I don't care. It is a thing of beauty. Those newer trains that make a high-pitched "eeeeee" sound drive me a little crazy. I understood the electrical part, but now I know why the different drive systems sound different. Thanks, Beno!
Back when I was studying Electrical Engineering at college, we spent months on DC motor drives, I still prefer Motor Generator sets rather than modern static converters, you can see and hear real engineering. Unstable electronics no thank you, give me the logic of a few thousand relays any day :)
Brilliant video! I’ve had a slight grasp of the idea of pulsing (I’m a tram driver, and we have gone from resistors to transistors (still DC, two types) to AC technology. The DC I understood, but have never had the AC principle explained so easily. However: Early single-phase electrificiation used low frequency AC. The Thamshavn-Løkken Railway uses 25 Hz, and the Norwegian/Swedish/German railways uses 16 2/3 Hz. I’ve been told they use DC motors somehow converted to AC, and the low phase prevents arcing (they are still using brushes and coiled rotors). 50 Hz could not be used until transistors came along, before then they used converters (rectifiers), such as the Ignitron (a kind of mercury arc rectifier), before reliable solid state rectifiers came along. Details about this are in the book "The history of the electric locomotive" by F. J. G. Haut (aviable in libraries and on Amazon). For which reason many railways electrified with direct current (France, Belgium, The Netherlands). More detalis are to be found in the book "Electric traction on railwas" by Philp Dawson, but this is a rather old and rare book. Keep up the good work! :D
The low frequency AC is for universal motors. The German railways use low frequency AC. A universal motor is a DC motor where both windings of the motor are wired in a way where changing direction causes both to change in a way that they counteract each other, so forwards force is produced both on positive and negative. The problem is that the voltage alternating has a reaction time that takes away efficiency. This means the lower the frequency the less the motors have the reaction delay, but if the frequency is too low the transformers supplying the power to the overhead line will stop working properly. To use universal motors you have to have a completely separate power supply, using a separate part of a power station, separate distribution lines just for it to work. That is a lot of inferstructure. Then a unerversal motor is less efficient than if it was just run on DC due to reaction losses. The only thing you gain is that you no longer let losses in the arc rectifier to convert the power to DC. But this is no longer a problem since the diode was invented.
Fantastic video! I've ridden on many of those types of trains over many years and gradually figured much of this out but it's great to see so much more. I witnessed a 1990's BART train blow a motor and drive as it was slowing down nearing a stop; I was in the station and there was a very very loud BANG the instant the descending tone switched to the final continuous drive tone; which I thought was most interesting. Within about a minute half the station was full of a thick, white yet nearly odorless smoke. I figured that transistor based drive and maybe some motor coil had met it's 1000 volts of instant DC death. Regarding the advancement of transistors, it seems the same thing is true for other types of motors. I work with old video tape machines and have noticed some very interesting and sometimes complicated methods of getting tapes to run at high (yet servo controlled) search speeds in the more expensive machines. I think I am hearing about 200 Hz as the maximum the coil switching speed in some of these capstan motors with parts originally designed in the early 1980's. When the machine is commanded to run at a slightly faster search speed the capstan motor just disengages and the machine switches to servo control of the direct drive dc reel motors (on some older machines). I'm guessing that is a duty cycle of less then 400 hz or so.
Now I know why trains make the noises that they do. Remember those double deck train in the netherlands from your amsterdam video's? They have a characteristic woop-woop sound that's a bit like the examples you've shown. The really old (now out of service) mat 64 trains from the 1960's had some characteristic sounds, they accalerated quickly but could also break quite fast making a sound that I've associated with the sound of waterfall. These trains also made you feel every shock of the rails like those old prague trains. Those Mat 64 trains where awsome.
You mean the DDZs? Those have a really funky sound, it's really interesting. The ICMs also sound really nice. I do wonder what kind of equipment those two have and what the engineers programmed in to make them do that. Apart from those, I think my favorites are the Austrian Taurus locos that play the major scale when accelerating.
This video was very interesting and brilliantly explained! Could you please reference some of the sources of information you used to make it? I would love to research this topic in more depth!
It isn't really fair to say that Direct Current motors themselves are SO much less efficient than a VFD and induction motor. A bit less efficient, perhaps, yes, but not dramatically so. Using resistors to control the DC motors IS terribly inefficient, as noted. The real advantage of the AC motor and VFD is the elimination of the maintenance of the brushes and commutator. I am and will always be partial to direct current machinery, and so am quick to point out that it actually isn't so bad as is assumed JUST because it's "old". BTW, speaking of that, you didn't mention the original way that Direct Current power for traction was obtained from Alternating Current supplies: Rotary Converters! There's a truly marvelous machine. ;)
I started going down this rabbit hole after riding Helsinki metro trains from late 70s/ early 80s. Learned they were apparently the first trains ever to use this technology and it’s really loud and very obvious compared to 90s trains. I really thought they had a gear box or something!
This is interesting I'd always wondered exactly what caused the step change pattern of sounds as electric vehicles accelerate, knowing that they don't feature gearing systems like combustion drives I assumed it had to be something on the input side of the drive motor but never really knew exactly what.
@@benolifts The Porshe Taycan Turbo S has two AC permanant magnet synchronous motors which seems to use pattern pulsing to drive it. This sound is amplified with the help of some speakers and can be heard here: ruclips.net/video/h0IAgkHpU54/видео.html
@@Cloudrak That is very weird that a Porsche sports car has pattern pulsing. Although I don't like these sorts of overpriced cars as they are status symbols and also in my opinion the bad side of capitalism when people lust over expensive items that are not necessary to have. I have noticed that Toyota Prius has possibly the same VF drive as the train on Warsaw metro that has the PWM pulsing change pitch in stages as the train starts. Also a few cheap generic lifts have this VF drive. If I owned a Prius I would see if I could lower the PWM frequency and make my car sound like a Warsaw metro train.
The technologies of which you speak were actually available a bit earlier. I remember reading in Robert Tufnell's _The Illustrated Encyclopedia of Railway Locomotives_ that some experimental German diesel-electric locomotive had AC propulsion in 1968 (I might be off by a year in either direction), and that French trains started using synchronous AC motors in the 1970s. Meanwhile, in my own experience not relying on 3rd party sources, the Boeing USSLRVs (often just called LRVs) used on the MBTA (Boston area, USA) and MUNI (San Francisco, USA) in the 1970s had electronic choppers that went up to 400 Hz, but were NOT constant-frequency when starting up; they also had a low voltage generator that had a lower frequency chopper, with the total result that they sounded like they were powered by tortured ghosts with terminal indigestion. They did have a provision for switching out the propulsion chopper once they got going fast enough. I have seen one unit (in a 2 car train) on which this mechanism was broken on one end so that the chopper was always cut out, and so full voltage was applied to the motor (each end had 1 motor for 2 axles) when starting; but contrary to your expectation, it didn't destroy the motor or even trip a circuit breaker, but instead spun the wheels on that end (with great slippage); likewise, during application of reverse voltage during dynamic braking, it spun the wheels on that end backwards. The 1980s-vintage Hiticha trains on the east-west line of MARTA (Atlanta, GA, USA) had the same electrical systems (both propulsion and low voltage power supply), resulting in the same sounds, although much muted due to better sound insulation on these cars (this disappeared after they were rebuilt with modern electrical systems in the late 2000s/early 2010s). The MBTA (Boston area) Type 7s (built by Kinki-Sharyo) of the 1980s were actually a technological step back from the Boeing cars -- they had constant-frequency choppers operating at 220 Hz that never cut out, and they went back to a motor-generator for the low voltage power supply, whose hum could get very loud if the bearings were going bad; these were also a weak point in that they could fail (probably because somebody forgot to change the motor brushes), and then the train would soon after become disabled once the low voltage battery discharged below a certain point (which didn't take very long). Edit: By the way, fixed-frequency AC motors have been used for traction, and still are, although now to a limited extent. Pioneering examples entering actual revenue service include the FS (Italian Railways) E550 and their successors using 2 wire 3 phase supply, and the original locomotives of the Virginian Railway (EL-C) and the Norfolk and Western that used single phase supply but used a rotary phase convert to make the polyphase electrical supply for the motors (I think these came even before Kalman Kando did the same thing in Hungary). Modern examples in revenue service include the Petit train de la Rhune (in France) and up to 3 other mountain railways (but I am not sure which of the others still actually feed fixed frequency AC to the motors as opposed to rectifying the input 3 phase current and then re-inverting it to make variable-frequency AC). Presumably these dealt with the problem of poor starting torque by using over-engineered motors, as well as liquid resistors ro limit current to keep the wheels from slipping and prevent overheating of the motors.
Thank you for making this - it is so underrated despite its importance, because even I have missed this video this first time round. If you have the time, are you able to make a video comparing how much power consumption is saved/used relative to each generation of technology used on trains (resistor - chopper - thyristor - GTO - IGBT - MOSFET)?
Best train noises: 1996 Jubilee Line trains Class 323 trains Siemens Taurus ‘singing’ locomotive 1992 Central Line stock Berlin S-Bahn Class 481/2 trains
Thank you very much indeed for posting this extremely interesting video. In it you explain exactly what I've been wanting to understand for ages; plus a lot more besides !! My own favourite sounds are those of the German ICE model 3 (and the improved Velaro D), together with some of the London Underground trains.
Have a look at a mercury arc rectifier, designed in 1902ish was a crude but well used way of converting ac to dc, the Manx electric railway used to use several
12:20 So the rate of the transistors is really easy to hear the 96 and 92 stock have lower frequency sounding ones. I need to watch the video again to properly understand it though. From a very brief overview though it seems like the more modern motors do a similar thing to the older dc motors but in a much more precise and controlled way or a way that allows the motors to work the way they do more naturally, if that even makes sense.
Skytrain in Vancouvers Mark 1 UTDCs are very distinctively GTO as the LIM really make it loud..very distinctive 1985 tech…only start being retired this year.
Singapore's C751A rolling stock (made in 2001-2) make a higher-pitched version of the '96 stock's sound; a difference I can think of is that the former uses 1.5kV DC from overhead wires instead. The newer C751C stock (made 2014-5) sound similar at lower speeds but at higher speeds sound more like the C830C stock (built at the same time & sounds like Amsterdam metro's M5 rolling stock) that runs on a different line that uses 750V DC from a 3rd rail instead
This is a really good video, with excellent annotations and commentary but I noticed some misleading imprecisions : #1 (5:30) As the motor starts, resistors must be sequentially *removed,* not turned on ! #2 (6:46 - 12:06) The first semiconductor equipment used as a switch to "pulse" the current from DC to DC was the thyristor, not transistor. It is limited as you said by its "chopping" frequency. By the way, such electronic apparatus is better known as chopper circuit (chopper control). Also, its wide adoption in trains began in the 70's. The first train driven by a thyristor-chopper in my country (Belgium) dates from 1970 ! The thyristor kept being produced until the 90's, depending on the country, etc. Eventually, basic transistors could be used as switches in chopper circuits, allowing higher switching frequency, but I don't know a single train model with this configuration. There is the modernised tram T5C5K but it was equiped with next-generation IGBT-transistor in 2002 (thanks hu.wikipedia), thus having nothing to do with 80's' transistors. Finally, GTO-thyristors and IGBT-transistors were both created in the 90's, having even better efficiency and allowing the use of 3 phases AC motors, in the now famous and melodious VFD's. ^_^ Apart from that, your video is excellent to popularize those underknown concepts ! Note to people interested : the clip at 6:01 can be found here : watch?v=BbvdBA4jygI
Oslo has two classes of thyristor-based trams, both dating from 1979-80. However, the second class (externally very similar to the older), has a newer thyristor equipment (you notice the different humming). Could be they have GTOs, as they came ≈5 years after the first (SL79I/SL79II). And we have a bunch of Ansaldo/Breda trams with AC motors and inverters (SL95). Presently awaiting new trams from CAF…
Hello Ciel, I just saw your reply, sorry for not responding earlier. The control device of SL79 clearly sounds like chopper :) Regarding the second batch (1989 126-140), the chopping frequency rises soon after departure, while it seems constant in the first batch (1982 101-125). Compare *watch?v=IlKMsIxxpqQ&t=2s* and *watch?v=IlKMsIxxpqQ&t=58s*. I found no reliable source on internet supporting the presence of GTO's but it could be the case. What can be said for sure is that the switching pattern of the latter control device is different. Speaking of SL95, judging by what I can hear, it must be IGBT-based inverters watch?v=SPLL0sIP6x8&t=237s
Um no. Unfortunately, Point number 1 is not valid, Beno got it bang on. I think your forgetting that these resistor banks are wired in Parallel not series. Its quite confusing but the total amount of resistance in a Parallel circuit is always LESS THAN (not equal to) the total amount of resistance in each of the circuit loops. A good way to visualise this is to think of current as little people (maybe passengers at a train station). If they are all forced to go through one of the circuit loops and through 1 lot of resistors at a time then they will all be squished and will slow down trying to get through. But if they were given the option to go another circuit bank AND the one they are currently using (remember in parallel circuits the Current is split between the different loops pretty much equally) then although the amount of resistance in the resistor remains the same throughout the circuit, the current is able to pass through easier. (Its like having multiple queues at the checkout and they open a new till and suddenly the process is twice as fast!) It seems counter intuitive, but this is the way it works.
Thanks, I think this is the only video that mentions anything about unusual traction sounds. Siemens did a bang up job with the VF drives on the Taurus locomotive, that plays a musical scale when moving off. Interestingly, the class 700 trains recently introduced make a really weird car alarm type sound when running off the middle rail, but a normal sound when running from overhead, I don't know if that just because they're using two entirely different and separate VF drives or what.
1::::2:::3::4:5:4::3:::2::::1:::::1::::3::5::3::::1:::::1:::3:5:3:::1 Have you heard a class 73 electrodiesel in electric mode. It takes a DC input, but sounds like it has VF, even though it was built in the 1960s.
Sydney Trains traction systems are as it follows: K sets and V sets V1-V27: Mitsubishi Electric camshaft resistance control, with DC series-wound motors V sets V28-V51 and T sets: Mitsubishi Electric GTO-4-quadrant chopper control, with 2-phase DC shunt-wound motors M sets: Alstom ONIX 1500 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors H sets: Mitsubishi Electric 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors A & B sets: Hitachi 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors The Sydney Metro uses Alstom OPTONIX 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors
And 2 more things you forgot to mention here: Random width, as heard on the S stock during its carrier-based pulsing. Spread spectrum, as heard on the Class 395 _Javelin._
So what you mentioned about the singular tone sound at the start being made by the transistors (6:42) makes sense to me. And it makes sense how you described the IGBTs and such, changing the pitch of the sound along with the motor/train speed itself. However what doesn't make sense to me is that some trains, such as, say the Alstom trains on the Washington metro (3000/6000 series) have only several constant pitches that change with the train speed, and no smooth variation at all - just jumping through pitches. Why would that be? Is that what you mentioned about IGBTs? Or is that the very last thing where you said it changes so there's no resonance?
Does Porsche Taycan also using this? Because the artificial sound is actually not artificial and it was an "futurized" recording of the motor sound, and the spaceship sound is similar to trains with VVVF
After so long, I have finally found a video that clearly explains why trains make these sounds. I'm so grateful for this video, thank you so much for your hard work!! I do have a question though; where can I learn more about this? Or in other words, how did YOU learn about this? Electrical engineering college course? Many youtube videos? Trained at a job that deals with this? Again, thank you so much and I can't wait to hear your response.
When I made this video there was very little on the internet about it. I had to teach myself a lot of things from going in lift motor rooms and playing with the VF drive settings until I learnt a lot of how it worked. Also, before I made this video there was only one video on the entire internet about this subject. Which is... ruclips.net/video/u6AUVwlhCis/видео.html This one is very informative with the oscilloscope. College and Uni taught me nothing about VF drives, it seems it was a specialist area that would only be taught if you were going into industry in designing them. Even the installers and companies that use VF drives are not involved in the back end programming of it. In the present day things have improved on the internet as there are now VF drive enthusiasts who program and build their own VF drives out of interest. I should have tried this myself, but I don't have time at the moment. Take a look at these videos of these VF drives that enthusiasts have hand built... ruclips.net/video/SKu6loq9kfg/видео.html ruclips.net/video/VCqwfJM1xyY/видео.html ruclips.net/video/4Zq70-QF1hE/видео.html
@@benolifts oh, wow. As a sound tens to hundreds of millions of people hear every day I would assume there would be more information about it online! Thanks for the information. You don't know just how much I appreciate this video. Thanks for your hard work!
I have no idea what half of this means; I just wanted to know why trains make the "rrreeeeeeererrrrrrr" noises when they pull off or slow down. Came away knowing a lot more than that.
Hey Beno! I might sound stupid but can we get this kind of sound from today's latest technology inverters like SiC MOSFET inverters? Though their switching frequency is extremely high, can we shape the sound like the 1990"s trains make with the help of some tweaking in the algorithm?
The switching technology of the inverter does not directly cause any change in motor sound. The sound that can be heard is the motor acting as a speaker. It is the way that the switching has been programmed that makes the sound. In the modern day a lot of inverters use either oscillating carrier frequency, or random (white noise) carrier frequency.
Can we use Frequency Modulation (FM) as in radios and digital synthesisers (I’m not sure) where a wave is used to modulate another(......I think) to control 3 phase AC motors, by having 3 Frequency modulators to control the 3 separate phases? If not, what is the reason behind this?
This is a brilliant video..and thank you for explaining how these changing frequency sounds are made..but could I ask..what exactly is making these Sounds? The electric motor ? Or the other electric equipment? And what exactly are these sounds , they are obviously something vibrating?
@@benolifts thank you .. but pardon my Ignorance...how is the sound actually being produced.. obviously air waves are vibrating against my ear drum for me to hear this sound but what is actually producing this sound at the motor level..IE the first high pitched sound happens even before the wheels start moving. .
@@diarmaiddillon1568 The VF drive starts before the brake releases for anti roll back protection. The creation of the sound is from the VF drive switching the supply, the frequency of this is the sound (not to be confused with the output frequency). The sound is emitted by the motor's winding coils which resinate the sound through the motor.
@@benolifts I would assume there's a minimum pulse width for whatever switching transducer they're using, and that this minimum pulse width would push too much current through the motors at the nominal PWM cycle frequency. To reduce the PWM duty cycle (and therefore time-averaged current) further, one can decrease the PWM cycle frequency. That way, a pulse of a certain duration would still make up a smaller proportion of the overall cycle, but without breaking the minimum pulse width rule. As speed goes up, the motor can take more voltage without drawing excessive current, so frequency can go up. The reason for the multiple frequency changes (which sound like gear changes) may well have more to do with the implementation. Typically a PWM circuit is built using a clock and two counters. One counter is used to set the cycle time (in effect it forces a reset after X many clock pulses) and the other determines the pulse width. It can set on-time or off-time, it really doesn't matter, but for this example let's go with on-time. So when reset, as long as the pulse width counter is less than or equal to the set point, the output is on. When it exceeds it's switched off. Because these machines are old, and in the past compute power came at a premium, the sensible approach to this would be to use a clock frequency which provides a pulse width that is just over the bare minimum. That way the counter buffers can be made narrower and thus the whole controller gets to be less expensive. This is where clever engineering comes in. The first few PWM increments are very wide relative to each other, so the frequency change trick from earlier can be reused to keep everything smooth. All that's needed is to adjust the set point for the cycle time counter and voila - variable frequency PWM. And because the entire range of that counter is available, we can be a lot more precise with the cycle frequency at that point. Less so at higher frequencies, but at that point the train is going fast enough that normal PWM gives enough control.
The reason for the reduction of pulses as set intervals as the motor speeds up is to keep the overall number of pulses per second within a range. Everytime the thristor switches states, it is completly instant. There is a very slight moment for a couple of nanoseconds that it is part on and part off. As heat disapates at the point of resistance, a half on thyistor has become the point of resistance and current is being dissipated. To reduce the amount of heat in the thyistor there is a limit of how many times it can be switched in a second. So in pattern mode, as the pattern speeds up, the amount of pulses in the pattern keeps being reduced to stop too many pulses per second. This happens until the motor is running at a faster speed, where it has less acceleration, meaning less current, after that the pulsing can speed up endlessly without more reductions to the pattern.
HELLO ?! Come on Beno, how risky would it be for you to tell me why some inner doors sound like they sound ? (I'm a lift surfer and urban explorer too just to remember you and I know that doing some things might put me at risk whilst others not much so).
Apart from being AC and DC, why does an AC desiro (350\360) make slightly different noises to a DC desiro (444\450) Do you know how 1995 stock motors work?
The 377s do that pulse sound around 32 mph on dc and 36-40mph and ac overhead wires, But that being said if it is just perfectionist programming that makes the motors sound .....a bit boring at the start ...and not a major benefit..then I'd much rather than switch it back to the way it used to be in the 90s
What about the Metrowoagonmash 81-718/719 in the Kharkiv Metro on the Oleksiivska line (green line)? I know they have the DC pulsing, but they don't sound the same as the 1996 Stock on the London Underground.
There are 3 sounds. These are the VF pulsing sound, the motor sound, and the train running along the track sound. The pulsing and motor sound sometimes makes an overtone. Also, the different motors and VF drives are not exactly in sync, which adds to the sound. When one VF drive changes pitch on one end of the carriage, the VF drive at the other end may do this one second later.
what makes that electrical 'tick... tick' sound that large diesel electric freight trains make when they are running but not moving my guess is that even at idle its generating electricity, and it has to go somewhere so every once in a while a relay goes off and somewhere a spark is created to dissipate the electricity? idk lol
When they are in "idle" (power lever set at 0), the generator field is open so it can't generate any electricity without the field voltage. You might be referring to the regular "tick tick" sound of the automatic water traps
You can convert ac to dc like the charger in your phone some are switching chargers I uster teach this a lot its like my alarm clock it plugs into ac in wall and converts it to 12 v dc. You can get a dc to ac converter circuit
A lift motor is much smaller than a train motor. The larger the load a transistor has to switch the lower the switching frequency needs must be (within the limits of the transistor technology used).
@@cheezyvids one year later, TYSM for the reply! I figured it must be the newer tech because of the sound. Lovely to have this confirmed! What does IGBT propulsion actually mean?
@@theblockybanana5537 IGBT is the type of transistor used because of the higher switching speed. Honestly, I’ve always thought the ‘95 trains sound identical to the A&B trains from the Prague Metro hah
The 1996 train has an early VF drive that switches from true PWM to pattern PWM at just 2 mph. The sound it makes is typical of and old style VF drive. It doesn't sound DC to me.
The Siemens Taurus locomotives make the absolutely best sound of all trains. It literally plays a musical scale while accelerating from a stop. There are countless videos of it on RUclips.
Idk, Siemens SITRAC could give it a run for its money.
@@camacakegd3714 The VIRM could do that too.
not even close. Keikyu 1000 series siemens gto vvvf playeda better song. And I mean way better.
@@AegisEdge You might not have checked what a Taurus is. The ES64U2 also has SIEMENS GTO modules like the 京急1000 and 2100 series, they also feature the musical scale during the asynchronous phase, and imo the scale sounds better on the Taurus. Not disregarding the 京急 trains tho, i love them and it’s sad to see them replaced with new IGBT modules. These singing Tauruses are still pretty common in Europe, here’s a video of a Taurus accelerating on its own fyi :)
ruclips.net/video/vxOUdp903UE/видео.htmlsi=mNtRQo7TeombXyTl
Russian EP20 sounds better.
I always felt that a train’s motor sounds made up a part of its “identity”, and I also kinda wondered how the sounds are made. I know part of it is due to electromagnetically-induced noise (coil whine), but I always wondered why even the same type of motors might sound different when they are from different manufacturers, etc.
This video definitely provides a good overview of what I always wanted to know.
This is a brilliant video! I was always wondering why electric trains make that sound! I personally love motor noise. My favourite motor noise comes from the Siemens Taurus, Class 455, Class 323 and Desiro.
Edmund Osborne just listened to the Siemens Taurus and its so crazy how it sounds like that
Vote 323 for president
Keikyu N1000- The musical train
Desiro? On overhead or on third rail?
I like the Class 395, Class 365-466, Class 700-717, Class 800-810, and more.
The synchronous (pattern based) mode is used to reduce motor current harmonics. The method is called "Selective Harmonic Eliminated PWM" or just "SHEPWM". And you are right, the transition between patterns is because of the limited maximum switching frequency - very well explained!
For asynchronous carrier based modulation there are many methods. More common nowadays is the Space Vector Modulation (because it creates less current harmonics) and in older drives you would find 'center-aligned' or 'edge-aligned' SPWM methods. All of these carrier based modulation methods can be used with a random generated carrier in a given range to reduce harmonics even further.
You mean pattern based, in contrast to a hard square wave, right? The closer you get to a proper sine wave, the less other sine frequencies you are going to have in the final motor drive frequency. Or do you mean you are making sure the pulse signal sent to the thyristors doesn't have any components above a certain frequency - the elimination of the too thin pulses as explained in the video?
The 1996, and 2009 stock makes the nicest noises
1992 and the D Stock are also cool
Not a big fan of the 2009 stock but I love the 1996 stock
2009 stock sounds like a future train for me
@@esftracksydeomg If you like the 1992 stock, the Class 319 is like the 1992TS, but with a lower pulsing frequency and just as epic-sounding.
The 2009 stock sounds like a ufo
6:00 Those DC motors sound so beautiful. Outdated technology? Yes. But I don't care. It is a thing of beauty. Those newer trains that make a high-pitched "eeeeee" sound drive me a little crazy. I understood the electrical part, but now I know why the different drive systems sound different. Thanks, Beno!
I like that sound the jubilee line 1996 stock makes.
Sonic the Freedom Fighter Same i also love central line
p Odunlami I also like the central line as well.
I also like the Berlin S-Bahn 481 sound
They sound similar to the C751A stock on Singapore's MRT (tube), though of a lower pitch
Jubilee is my favourite line because of that sound
These sounds, I must say, for some reason I find them so satisfying : D
Back when I was studying Electrical Engineering at college, we spent months on DC motor drives, I still prefer Motor Generator sets rather than modern static converters, you can see and hear real engineering.
Unstable electronics no thank you, give me the logic of a few thousand relays any day :)
Brilliant video! I’ve had a slight grasp of the idea of pulsing (I’m a tram driver, and we have gone from resistors to transistors (still DC, two types) to AC technology. The DC I understood, but have never had the AC principle explained so easily.
However: Early single-phase electrificiation used low frequency AC. The Thamshavn-Løkken Railway uses 25 Hz, and the Norwegian/Swedish/German railways uses 16 2/3 Hz. I’ve been told they use DC motors somehow converted to AC, and the low phase prevents arcing (they are still using brushes and coiled rotors).
50 Hz could not be used until transistors came along, before then they used converters (rectifiers), such as the Ignitron (a kind of mercury arc rectifier), before reliable solid state rectifiers came along.
Details about this are in the book "The history of the electric locomotive" by F. J. G. Haut (aviable in libraries and on Amazon).
For which reason many railways electrified with direct current (France, Belgium, The Netherlands).
More detalis are to be found in the book "Electric traction on railwas" by Philp Dawson, but this is a rather old and rare book.
Keep up the good work! :D
The low frequency AC is for universal motors. The German railways use low frequency AC. A universal motor is a DC motor where both windings of the motor are wired in a way where changing direction causes both to change in a way that they counteract each other, so forwards force is produced both on positive and negative. The problem is that the voltage alternating has a reaction time that takes away efficiency. This means the lower the frequency the less the motors have the reaction delay, but if the frequency is too low the transformers supplying the power to the overhead line will stop working properly. To use universal motors you have to have a completely separate power supply, using a separate part of a power station, separate distribution lines just for it to work. That is a lot of inferstructure. Then a unerversal motor is less efficient than if it was just run on DC due to reaction losses. The only thing you gain is that you no longer let losses in the arc rectifier to convert the power to DC. But this is no longer a problem since the diode was invented.
I thought it was because they recycled parts from the war of the worlds tripods.
Fantastic video! I've ridden on many of those types of trains over many years and gradually figured much of this out but it's great to see so much more. I witnessed a 1990's BART train blow a motor and drive as it was slowing down nearing a stop; I was in the station and there was a very very loud BANG the instant the descending tone switched to the final continuous drive tone; which I thought was most interesting. Within about a minute half the station was full of a thick, white yet nearly odorless smoke. I figured that transistor based drive and maybe some motor coil had met it's 1000 volts of instant DC death.
Regarding the advancement of transistors, it seems the same thing is true for other types of motors. I work with old video tape machines and have noticed some very interesting and sometimes complicated methods of getting tapes to run at high (yet servo controlled) search speeds in the more expensive machines. I think I am hearing about 200 Hz as the maximum the coil switching speed in some of these capstan motors with parts originally designed in the early 1980's. When the machine is commanded to run at a slightly faster search speed the capstan motor just disengages and the machine switches to servo control of the direct drive dc reel motors (on some older machines). I'm guessing that is a duty cycle of less then 400 hz or so.
Now I know why trains make the noises that they do. Remember those double deck train in the netherlands from your amsterdam video's? They have a characteristic woop-woop sound that's a bit like the examples you've shown. The really old (now out of service) mat 64 trains from the 1960's had some characteristic sounds, they accalerated quickly but could also break quite fast making a sound that I've associated with the sound of waterfall. These trains also made you feel every shock of the rails like those old prague trains. Those Mat 64 trains where awsome.
You mean the DDZs? Those have a really funky sound, it's really interesting. The ICMs also sound really nice. I do wonder what kind of equipment those two have and what the engineers programmed in to make them do that. Apart from those, I think my favorites are the Austrian Taurus locos that play the major scale when accelerating.
@@WhyFi59 pretty sure the ICMm has Chopper's. not sure about DDZ.
This video was very interesting and brilliantly explained! Could you please reference some of the sources of information you used to make it? I would love to research this topic in more depth!
It isn't really fair to say that Direct Current motors themselves are SO much less efficient than a VFD and induction motor. A bit less efficient, perhaps, yes, but not dramatically so. Using resistors to control the DC motors IS terribly inefficient, as noted. The real advantage of the AC motor and VFD is the elimination of the maintenance of the brushes and commutator. I am and will always be partial to direct current machinery, and so am quick to point out that it actually isn't so bad as is assumed JUST because it's "old". BTW, speaking of that, you didn't mention the original way that Direct Current power for traction was obtained from Alternating Current supplies: Rotary Converters! There's a truly marvelous machine. ;)
I guess that's why you can reduce that frequency to make lifts sound nice.
Knuckles the Echidna Wait, you know about trains?!?!?!
DO YOU NO DE WAE
I started going down this rabbit hole after riding Helsinki metro trains from late 70s/ early 80s. Learned they were apparently the first trains ever to use this technology and it’s really loud and very obvious compared to 90s trains. I really thought they had a gear box or something!
This is interesting I'd always wondered exactly what caused the step change pattern of sounds as electric vehicles accelerate, knowing that they don't feature gearing systems like combustion drives I assumed it had to be something on the input side of the drive motor but never really knew exactly what.
I wish one day that one person makes an electric car with 90s pulsing patterns.
When I get an electric car I will be going through setting on the OBD to see if I can get to the VF carrier frequency setting
@@benolifts The Porshe Taycan Turbo S has two AC permanant magnet synchronous motors which seems to use pattern pulsing to drive it. This sound is amplified with the help of some speakers and can be heard here: ruclips.net/video/h0IAgkHpU54/видео.html
@@benolifts Oh and for the BMW i3 ev, you cannot change anything drivetrain based through Bimmercode on a OBD2 reader.
@@Cloudrak That is very weird that a Porsche sports car has pattern pulsing. Although I don't like these sorts of overpriced cars as they are status symbols and also in my opinion the bad side of capitalism when people lust over expensive items that are not necessary to have.
I have noticed that Toyota Prius has possibly the same VF drive as the train on Warsaw metro that has the PWM pulsing change pitch in stages as the train starts. Also a few cheap generic lifts have this VF drive. If I owned a Prius I would see if I could lower the PWM frequency and make my car sound like a Warsaw metro train.
The technologies of which you speak were actually available a bit earlier. I remember reading in Robert Tufnell's _The Illustrated Encyclopedia of Railway Locomotives_ that some experimental German diesel-electric locomotive had AC propulsion in 1968 (I might be off by a year in either direction), and that French trains started using synchronous AC motors in the 1970s. Meanwhile, in my own experience not relying on 3rd party sources, the Boeing USSLRVs (often just called LRVs) used on the MBTA (Boston area, USA) and MUNI (San Francisco, USA) in the 1970s had electronic choppers that went up to 400 Hz, but were NOT constant-frequency when starting up; they also had a low voltage generator that had a lower frequency chopper, with the total result that they sounded like they were powered by tortured ghosts with terminal indigestion. They did have a provision for switching out the propulsion chopper once they got going fast enough. I have seen one unit (in a 2 car train) on which this mechanism was broken on one end so that the chopper was always cut out, and so full voltage was applied to the motor (each end had 1 motor for 2 axles) when starting; but contrary to your expectation, it didn't destroy the motor or even trip a circuit breaker, but instead spun the wheels on that end (with great slippage); likewise, during application of reverse voltage during dynamic braking, it spun the wheels on that end backwards. The 1980s-vintage Hiticha trains on the east-west line of MARTA (Atlanta, GA, USA) had the same electrical systems (both propulsion and low voltage power supply), resulting in the same sounds, although much muted due to better sound insulation on these cars (this disappeared after they were rebuilt with modern electrical systems in the late 2000s/early 2010s). The MBTA (Boston area) Type 7s (built by Kinki-Sharyo) of the 1980s were actually a technological step back from the Boeing cars -- they had constant-frequency choppers operating at 220 Hz that never cut out, and they went back to a motor-generator for the low voltage power supply, whose hum could get very loud if the bearings were going bad; these were also a weak point in that they could fail (probably because somebody forgot to change the motor brushes), and then the train would soon after become disabled once the low voltage battery discharged below a certain point (which didn't take very long).
Edit: By the way, fixed-frequency AC motors have been used for traction, and still are, although now to a limited extent. Pioneering examples entering actual revenue service include the FS (Italian Railways) E550 and their successors using 2 wire 3 phase supply, and the original locomotives of the Virginian Railway (EL-C) and the Norfolk and Western that used single phase supply but used a rotary phase convert to make the polyphase electrical supply for the motors (I think these came even before Kalman Kando did the same thing in Hungary). Modern examples in revenue service include the Petit train de la Rhune (in France) and up to 3 other mountain railways (but I am not sure which of the others still actually feed fixed frequency AC to the motors as opposed to rectifying the input 3 phase current and then re-inverting it to make variable-frequency AC). Presumably these dealt with the problem of poor starting torque by using over-engineered motors, as well as liquid resistors ro limit current to keep the wheels from slipping and prevent overheating of the motors.
Thank you for making this - it is so underrated despite its importance, because even I have missed this video this first time round. If you have the time, are you able to make a video comparing how much power consumption is saved/used relative to each generation of technology used on trains (resistor - chopper - thyristor - GTO - IGBT - MOSFET)?
I have heard that sound on few modern trains too.
Jubilee line train has the best sound with the southeastern 466 train they both sound similar.
Best train noises:
1996 Jubilee Line trains
Class 323 trains
Siemens Taurus ‘singing’ locomotive
1992 Central Line stock
Berlin S-Bahn Class 481/2 trains
Oh... they're literally just oversized audio synthesizers you'd find in 80-90s game consoles :P
I recently started riding the Metra Electric into Chicago and I’ve been really curious about this. Thank you sir 🫡
South Shore Line motor sounds awesome
I like the 1996 stock and class 450 also 444 and beno is smart
6:00 sound like hanging or camshaft
7:46 you could do it using led lights the higher the faster there flash the lower the slower there flash I learnt this in radio communications course
Thank you very much indeed for posting this extremely interesting video.
In it you explain exactly what I've been wanting to understand for ages; plus a lot more besides !!
My own favourite sounds are those of the German ICE model 3 (and the improved Velaro D), together with some of the London Underground trains.
This is the principle of a variable speed drive.
Have a look at a mercury arc rectifier, designed in 1902ish was a crude but well used way of converting ac to dc, the Manx electric railway used to use several
rickyreynolds17 It has to be the most beautiful way to convert AC into DC. It looks better than a rotary converter.
@@buddyclem7328 They are also without moving parts… I guess with proper cooling they last "forever", as on the MER. :)
Great video. ☺️
So what I understand from the transistor explanation at 6:46 is that the dutch ICM(m) has 2 types of transistors and then switches over?
Thanks Ben! Very informative!
12:20 So the rate of the transistors is really easy to hear the 96 and 92 stock have lower frequency sounding ones. I need to watch the video again to properly understand it though.
From a very brief overview though it seems like the more modern motors do a similar thing to the older dc motors but in a much more precise and controlled way or a way that allows the motors to work the way they do more naturally, if that even makes sense.
Skytrain in Vancouvers Mark 1 UTDCs are very distinctively GTO as the LIM really make it loud..very distinctive 1985 tech…only start being retired this year.
Great explanation, but my only criticism is maybe just slow down the explanation a little bit, it becomes kind of hard to follow you at some points.
Singapore's C751A rolling stock (made in 2001-2) make a higher-pitched version of the '96 stock's sound; a difference I can think of is that the former uses 1.5kV DC from overhead wires instead. The newer C751C stock (made 2014-5) sound similar at lower speeds but at higher speeds sound more like the C830C stock (built at the same time & sounds like Amsterdam metro's M5 rolling stock) that runs on a different line that uses 750V DC from a 3rd rail instead
My best friend thinks that the Jubilee Line Motor sounds like a dead cat.
Most interesting video I've seen in a while. Keep up good work!
Interesting question - how do Junipers make that thrashy sound? I hear it every time I’m on a 334 sat in the back of the front coach or vice versa.
If you hear the C751A and C751C motor sound, it sounds 'melodic' to you
I'm sure many people think you're crazy. But you really know your sh*t! Thumbs-Up
Great Vid, why is it that the class 323s make so many different sounds just to get to 20 mph
Hey ben, what video editor do u use to edit your videos?
This is a really good video, with excellent annotations and commentary but I noticed some misleading imprecisions :
#1 (5:30) As the motor starts, resistors must be sequentially *removed,* not turned on !
#2 (6:46 - 12:06) The first semiconductor equipment used as a switch to "pulse" the current from DC to DC was the thyristor, not transistor. It is limited as you said by its "chopping" frequency. By the way, such electronic apparatus is better known as chopper circuit (chopper control). Also, its wide adoption in trains began in the 70's. The first train driven by a thyristor-chopper in my country (Belgium) dates from 1970 ! The thyristor kept being produced until the 90's, depending on the country, etc.
Eventually, basic transistors could be used as switches in chopper circuits, allowing higher switching frequency, but I don't know a single train model with this configuration. There is the modernised tram T5C5K but it was equiped with next-generation IGBT-transistor in 2002 (thanks hu.wikipedia), thus having nothing to do with 80's' transistors.
Finally, GTO-thyristors and IGBT-transistors were both created in the 90's, having even better efficiency and allowing the use of 3 phases AC motors, in the now famous and melodious VFD's. ^_^
Apart from that, your video is excellent to popularize those underknown concepts !
Note to people interested : the clip at 6:01 can be found here : watch?v=BbvdBA4jygI
Oslo has two classes of thyristor-based trams, both dating from 1979-80. However, the second class (externally very similar to the older), has a newer thyristor equipment (you notice the different humming). Could be they have GTOs, as they came ≈5 years after the first (SL79I/SL79II).
And we have a bunch of Ansaldo/Breda trams with AC motors and inverters (SL95). Presently awaiting new trams from CAF…
Hello Ciel, I just saw your reply, sorry for not responding earlier.
The control device of SL79 clearly sounds like chopper :) Regarding the second batch (1989 126-140), the chopping frequency rises soon after departure, while it seems constant in the first batch (1982 101-125). Compare *watch?v=IlKMsIxxpqQ&t=2s* and *watch?v=IlKMsIxxpqQ&t=58s*. I found no reliable source on internet supporting the presence of GTO's but it could be the case. What can be said for sure is that the switching pattern of the latter control device is different.
Speaking of SL95, judging by what I can hear, it must be IGBT-based inverters watch?v=SPLL0sIP6x8&t=237s
Um no. Unfortunately, Point number 1 is not valid, Beno got it bang on.
I think your forgetting that these resistor banks are wired in Parallel not series. Its quite confusing but the total amount of resistance in a Parallel circuit is always LESS THAN (not equal to) the total amount of resistance in each of the circuit loops.
A good way to visualise this is to think of current as little people (maybe passengers at a train station). If they are all forced to go through one of the circuit loops and through 1 lot of resistors at a time then they will all be squished and will slow down trying to get through. But if they were given the option to go another circuit bank AND the one they are currently using (remember in parallel circuits the Current is split between the different loops pretty much equally) then although the amount of resistance in the resistor remains the same throughout the circuit, the current is able to pass through easier.
(Its like having multiple queues at the checkout and they open a new till and suddenly the process is twice as fast!) It seems counter intuitive, but this is the way it works.
Thanks, I think this is the only video that mentions anything about unusual traction sounds. Siemens did a bang up job with the VF drives on the Taurus locomotive, that plays a musical scale when moving off. Interestingly, the class 700 trains recently introduced make a really weird car alarm type sound when running off the middle rail, but a normal sound when running from overhead, I don't know if that just because they're using two entirely different and separate VF drives or what.
Well, overhead is fed in AC while when on 3rd rail it uses DC
Great video, learnt a lot, thank you.
I like the 377 sound,313 and 1996 sound.
And 319 (although i hate that train)
fab video beno! I am still quite partial to the clunky clunk and the feeling of resistor banks tho!
So it's the coil whine? EM induced acoustic noise? The same 50 Hz hum that comes from the power substation?
Thanks for the great video!
In the last section, what time did the switching occur? 14:59 ? (when high freq sound can't be heared?)
1::::2:::3::4:5:4::3:::2::::1:::::1::::3::5::3::::1:::::1:::3:5:3:::1
Have you heard a class 73 electrodiesel in electric mode. It takes a DC input, but sounds like it has VF, even though it was built in the 1960s.
Sydney Trains traction systems are as it follows:
K sets and V sets V1-V27: Mitsubishi Electric camshaft resistance control, with DC series-wound motors
V sets V28-V51 and T sets: Mitsubishi Electric GTO-4-quadrant chopper control, with 2-phase DC shunt-wound motors
M sets: Alstom ONIX 1500 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors
H sets: Mitsubishi Electric 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors
A & B sets: Hitachi 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors
The Sydney Metro uses Alstom OPTONIX 2-level IGBT-VVVF inverter control, with 3-phase AC induction motors
Camshaft sound like hanging resistance control
What explains the cooling fan noise on alstom trains such as 465s 1996, and 1995 stocks. They make the motor thrash sound really good
And 2 more things you forgot to mention here:
Random width, as heard on the S stock during its carrier-based pulsing.
Spread spectrum, as heard on the Class 395 _Javelin._
He did mention R-PWM at the end of the video...
I like the sounds of these trains
So what you mentioned about the singular tone sound at the start being made by the transistors (6:42) makes sense to me. And it makes sense how you described the IGBTs and such, changing the pitch of the sound along with the motor/train speed itself. However what doesn't make sense to me is that some trains, such as, say the Alstom trains on the Washington metro (3000/6000 series) have only several constant pitches that change with the train speed, and no smooth variation at all - just jumping through pitches. Why would that be? Is that what you mentioned about IGBTs? Or is that the very last thing where you said it changes so there's no resonance?
Impossible how the 96 stock sounds were made by accident
Does Porsche Taycan also using this? Because the artificial sound is actually not artificial and it was an "futurized" recording of the motor sound, and the spaceship sound is similar to trains with VVVF
Why do new trains make the arching like sound before accelerating. The S stock and some adventras.
After so long, I have finally found a video that clearly explains why trains make these sounds. I'm so grateful for this video, thank you so much for your hard work!! I do have a question though; where can I learn more about this? Or in other words, how did YOU learn about this? Electrical engineering college course? Many youtube videos? Trained at a job that deals with this? Again, thank you so much and I can't wait to hear your response.
When I made this video there was very little on the internet about it. I had to teach myself a lot of things from going in lift motor rooms and playing with the VF drive settings until I learnt a lot of how it worked. Also, before I made this video there was only one video on the entire internet about this subject. Which is...
ruclips.net/video/u6AUVwlhCis/видео.html
This one is very informative with the oscilloscope.
College and Uni taught me nothing about VF drives, it seems it was a specialist area that would only be taught if you were going into industry in designing them. Even the installers and companies that use VF drives are not involved in the back end programming of it.
In the present day things have improved on the internet as there are now VF drive enthusiasts who program and build their own VF drives out of interest. I should have tried this myself, but I don't have time at the moment.
Take a look at these videos of these VF drives that enthusiasts have hand built...
ruclips.net/video/SKu6loq9kfg/видео.html
ruclips.net/video/VCqwfJM1xyY/видео.html
ruclips.net/video/4Zq70-QF1hE/видео.html
@@benolifts oh, wow. As a sound tens to hundreds of millions of people hear every day I would assume there would be more information about it online! Thanks for the information. You don't know just how much I appreciate this video. Thanks for your hard work!
Excellent! Very clear explanation
I have no idea what half of this means; I just wanted to know why trains make the "rrreeeeeeererrrrrrr" noises when they pull off or slow down. Came away knowing a lot more than that.
Hey Beno! I might sound stupid but can we get this kind of sound from today's latest technology inverters like SiC MOSFET inverters? Though their switching frequency is extremely high, can we shape the sound like the 1990"s trains make with the help of some tweaking in the algorithm?
The switching technology of the inverter does not directly cause any change in motor sound. The sound that can be heard is the motor acting as a speaker. It is the way that the switching has been programmed that makes the sound. In the modern day a lot of inverters use either oscillating carrier frequency, or random (white noise) carrier frequency.
Why aren't they programed like the 323
Can we use Frequency Modulation (FM) as in radios and digital synthesisers (I’m not sure) where a wave is used to modulate another(......I think) to control 3 phase AC motors, by having 3 Frequency modulators to control the 3 separate phases? If not, what is the reason behind this?
*intense train sound*
This is a brilliant video..and thank you for explaining how these changing frequency sounds are made..but could I ask..what exactly is making these Sounds? The electric motor ? Or the other electric equipment? And what exactly are these sounds , they are obviously something vibrating?
It is the windings of the motor. Any coil can act as a speaker.
@@benolifts thank you .. but pardon my Ignorance...how is the sound actually being produced.. obviously air waves are vibrating against my ear drum for me to hear this sound but what is actually producing this sound at the motor level..IE the first high pitched sound happens even before the wheels start moving. .
@@diarmaiddillon1568 The VF drive starts before the brake releases for anti roll back protection. The creation of the sound is from the VF drive switching the supply, the frequency of this is the sound (not to be confused with the output frequency). The sound is emitted by the motor's winding coils which resinate the sound through the motor.
Why do some inner lift doors sound like an IV line machine then ?
But why does the 1995 train, its very similar cousin, not make that sound even though it’s slightly older, it sounds like it has a newer VF
Effing brilliant 🙌🏽
I assume it was easier to change frequencies smoothly rather than pulse width.
How do you mean?
@@benolifts I would assume there's a minimum pulse width for whatever switching transducer they're using, and that this minimum pulse width would push too much current through the motors at the nominal PWM cycle frequency.
To reduce the PWM duty cycle (and therefore time-averaged current) further, one can decrease the PWM cycle frequency. That way, a pulse of a certain duration would still make up a smaller proportion of the overall cycle, but without breaking the minimum pulse width rule. As speed goes up, the motor can take more voltage without drawing excessive current, so frequency can go up.
The reason for the multiple frequency changes (which sound like gear changes) may well have more to do with the implementation. Typically a PWM circuit is built using a clock and two counters. One counter is used to set the cycle time (in effect it forces a reset after X many clock pulses) and the other determines the pulse width. It can set on-time or off-time, it really doesn't matter, but for this example let's go with on-time. So when reset, as long as the pulse width counter is less than or equal to the set point, the output is on. When it exceeds it's switched off.
Because these machines are old, and in the past compute power came at a premium, the sensible approach to this would be to use a clock frequency which provides a pulse width that is just over the bare minimum. That way the counter buffers can be made narrower and thus the whole controller gets to be less expensive. This is where clever engineering comes in. The first few PWM increments are very wide relative to each other, so the frequency change trick from earlier can be reused to keep everything smooth. All that's needed is to adjust the set point for the cycle time counter and voila - variable frequency PWM. And because the entire range of that counter is available, we can be a lot more precise with the cycle frequency at that point. Less so at higher frequencies, but at that point the train is going fast enough that normal PWM gives enough control.
The reason for the reduction of pulses as set intervals as the motor speeds up is to keep the overall number of pulses per second within a range. Everytime the thristor switches states, it is completly instant. There is a very slight moment for a couple of nanoseconds that it is part on and part off. As heat disapates at the point of resistance, a half on thyistor has become the point of resistance and current is being dissipated. To reduce the amount of heat in the thyistor there is a limit of how many times it can be switched in a second. So in pattern mode, as the pattern speeds up, the amount of pulses in the pattern keeps being reduced to stop too many pulses per second. This happens until the motor is running at a faster speed, where it has less acceleration, meaning less current, after that the pulsing can speed up endlessly without more reductions to the pattern.
HELLO ?!
Come on Beno, how risky would it be for you to tell me why some inner doors sound like they sound ?
(I'm a lift surfer and urban explorer too just to remember you and I know that doing some things might put me at risk whilst others not much so).
Apart from being AC and DC, why does an AC desiro (350\360) make slightly different noises to a DC desiro (444\450)
Do you know how 1995 stock motors work?
The 377s do that pulse sound around 32 mph on dc and 36-40mph and ac overhead wires, But that being said if it is just perfectionist programming that makes the motors sound .....a bit boring at the start ...and not a major benefit..then I'd much rather than switch it back to the way it used to be in the 90s
Is the the one you mention at the end, the one that sounds like a alarm going off.
Favourite video. 323 is best. Beno an electrical engineer?
whats the first part of the sound (0:02), the really harsh sound before it starts to accelerate and make the rising tones?
6:42 is the explanation
What about the Metrowoagonmash 81-718/719 in the Kharkiv Metro on the Oleksiivska line (green line)? I know they have the DC pulsing, but they don't sound the same as the 1996 Stock on the London Underground.
The 1996 on London underground does not have DC pulsing. It has AC pulsing.
Thanks maite.
In Czech republic we have a train called city elephant (Actual name; not translated). It makes the CLEANEST "electric train sounds"
And then there's SiC
great video! my only confusion is, for example on the 2009 underground stock, why does the sound seem to have "overtones"?
....are there two sources of sound or one?
There are 3 sounds. These are the VF pulsing sound, the motor sound, and the train running along the track sound. The pulsing and motor sound sometimes makes an overtone. Also, the different motors and VF drives are not exactly in sync, which adds to the sound. When one VF drive changes pitch on one end of the carriage, the VF drive at the other end may do this one second later.
I miss keikyu gto vvvf
what makes that electrical 'tick... tick' sound that large diesel electric freight trains make when they are running but not moving
my guess is that even at idle its generating electricity, and it has to go somewhere so every once in a while a relay goes off and somewhere a spark is created to dissipate the electricity? idk lol
When they are in "idle" (power lever set at 0), the generator field is open so it can't generate any electricity without the field voltage.
You might be referring to the regular "tick tick" sound of the automatic water traps
thats really interesting, i don't know what that is so i'll learn something new!!@@xeels2708
So, did anyone ever put thyratrons on a train?
Brilliant video Beno you should get a look at the new scotrails trains on the ENG line they sound amazing
DixieNormous561 I do actually like the new 385 traction motors.
At the start the train sounds like a networker
Same drive.
You can convert ac to dc like the charger in your phone some are switching chargers I uster teach this a lot its like my alarm clock it plugs into ac in wall and converts it to 12 v dc. You can get a dc to ac converter circuit
Why was this re-uploaded twice
due to errors
ok
Why class 456s has silent motors ?
Why did the 90s kone ecodisc lifts not make the 90s vvvf sound?
A lift motor is much smaller than a train motor. The larger the load a transistor has to switch the lower the switching frequency needs must be (within the limits of the transistor technology used).
Ever heard the Dutch VIRM trains?
frequency changer ❤
If it’s due to the tech at the time, why does the 1996 stock pulse when the older 1995 stock doesn’t?
Funnily enough the 1995 stock is actually the newer one, already using IGBT propulsion
@@cheezyvids one year later, TYSM for the reply! I figured it must be the newer tech because of the sound. Lovely to have this confirmed! What does IGBT propulsion actually mean?
@@theblockybanana5537 IGBT is the type of transistor used because of the higher switching speed.
Honestly, I’ve always thought the ‘95 trains sound identical to the A&B trains from the Prague Metro hah
If the '96 train has AC motors, then why does it make the sound of the transistors reducing the inrush of current to the DC motors?
The 1996 train has an early VF drive that switches from true PWM to pattern PWM at just 2 mph. The sound it makes is typical of and old style VF drive. It doesn't sound DC to me.
I have a diode bridge somewhere as on 9:27
Electric vehicles whine as well :)