Electric scooter sings as it travels

This scooter has been fitted with a three-phase induction motor. It reminds us of the sound effects from vehicles in the Jetsons. Right now they’re using lead-acid batteries and get about 15 miles of range from one charge. Once they switch over to lithium polymer they calculate the range will be closer to 45 miles due to the reduced weight and increased capacity. Not bad for $600 in parts, and we’d bet it’s both faster and more stable than the one-wheeled-wonder we saw last week.

Comments

  1. po says:

    It Sings!

  2. Jake says:

    I was in Elk Rapids, Michigan this weekend. Some kid went by us on a moped, he had a full sound system on the thing – It even had decent bass. It was LOUD!

    That’s what I thought this hack was about ;)

  3. Jake says:

    Hahaha, he calls the changing duty of the FETS “the changing of the gears”

  4. kaaaaaaang says:

    What is the exact function of the exahusts? decorative?

  5. sunjester says:

    And?

  6. Sci says:

    @kaaaaaaang Umm, what exhausts? Do you mean the fairing?

  7. extermin8tor says:

    The guy who filmed it looks like Niko Bellic from GTA IV, he even sounds like him :)
    They scooter looks pretty good, I used to have a 200 watt electric scooter that had the same body style and MAN that thing was fast, 50 KM/HR @ 48 volts, 50 KM range.
    However the state government passed a memorandum that basically prohibits electric scooters, and only allows assisted bicycles, due to the number of people riding those things irresponsibly (mainly no helmet, on sidewalks at 50 km/hr, on bike trails, etc).

  8. grenadier says:

    Enough with people slapping tesla’s name on everything!

  9. cuttlefsh says:

    @grenadier they need to make a “Tesla Toothbrush”

  10. Drayon84 says:

    Custom electric mopeds and scooters are getting more popular. In a few months I’ll have to send my Honda PA50II conversion here when I’m done.

  11. Rustybadger says:

    The sound reminds me of Kirk’s electric motorbike in the latest Trek film.

    And these guys actually CAN put Tesla’s name on it, since they’re using an AC motor (as opposed to DC systems, which would have to be named after the King of DC, Thomas Edison). Besides, we should be naming EVERYTHING after Tesla, since he rocked!

  12. svofski says:

    This sound is indicative of very coarse AC motor control. This scooter could be made much more efficient and practically silent, but it’s a great start.

  13. Gert says:

    If we ever develop good and affordable batteries for
    electric transport we still have the noise to work out. Electric cars have a very high pitch noise.
    Combine that with todays plastic cars and you have a noise that’ll become unbearable after a few minutes.

    One question about the scooter. How hot do those mosfets get?

  14. James says:

    No-one else worried by the chap burying a body at the side of the road?

    I like it, clean, simple, does the trick.

  15. hanneshow the says:

    I this kind of hacking legal in France? I would love to build something like that, but german police would kick my ass when they caught me.

    @James: yeah, that guy digging there looked kinda awkward. But hell, that seemed to be rural France so maybe that’s how things work there :)

  16. Hackius says:

    It’s rural Macedonia!

  17. Chris says:

    What is the benefit of using an AC motor? Seems like converting from battery DC to AC would be less efficient.

  18. Quizme says:

    I wish Toyota would put a sound system on their hybrids when they are going slow or start moving. I got hit in the knee when walking by a prius parallel parked in a parking lot when it lurched out, no warning no light indicator. Scared the crap out of me!

  19. ravenacious says:

    Quite a nice scooter. Doesn’t look too much like a massive hack either.

    The best thing about this video is the dude in the background going at what looks like it might one day be a pavement with a pick axe. What’s that about?!!?

  20. NoName says:

    @Chris
    Actually when you’re varying the speed of a DC motor, you’re sending a PWM signal to it which is already similar to what you do when trying to do a DC to AC conversion. You would use an AC motor because they can typically have better efficiency, and superior power curves than a DC motor. Downside is that the motor controller for them is much more complicated.

  21. jonored says:

    @Chris – Actually, it’s worth note that a normal DC motor boils down to an AC device mechanically coupled to a simple converter from DC to AC. To my knowledge only a homopolar motor actually directly uses a DC current, and that’s not exactly got much oomph to it. So it really is about the complexity and cost vs. efficiency, and for something high-power like this, the beefy semiconductors aren’t that expensive and are mostly just better.

  22. lee says:

    Can someone explain why it sings? duty cycles? be gentle if you plan to flame me for asking a question… =)

  23. Justin says:

    @lee – The noise is from the PWM switching action of the power supply driving the motor. The noise is pretty considerable, which tells me that the supply has a low switching frequency, say in the neighborhood of 2-6 kHz. Another possible reason is that it uses hysteretic control, meaning that the switches only turn on or off when the motor current gets too far away from its target (commanded) value. In other words, having a variable switching frequency.

    Don’t worry, no flames :)

  24. Cory says:

    lee– Tones are a constant frequency you can hear. Humans are can hear from 20Hz-18kHz (generally). On the bike there are two sources of frequency:

    1. The sine waves driving the motor and are proportional to the RPM of the motor — this will be < 400Hz, like the buzz you hear from a loaded transformer (60Hz)
    2. One which chops the battery voltage to approximate a sine wave

    All they do is adjust the frequency of #2, which does not change the duty cycle. The duty cycle is used to control the speed/torque of the motor.

    The reason it "sings" is the windings in the motor actually vibrate at that frequency, like a giant speaker.

  25. jeditalian says:

    i need to get ahold of one of those scooters, it looks pretty light. not after you put lead batteries in it, though. there is plenty of room for battery. throw in 96+ volts of LiPo and speed controller, and a motor that doesnt convert energy into noise so much, although it would be fun to play music with your throttle. then, you have an excellent source of transportation instead of just a slow, short range one.

  26. Igor says:

    The best electric scooter produced in Macedonia ever !!!

  27. Vasko says:

    It’s has 9 batteries now and about 120 volts. Peak current more than 80A and a peak power of about 10kW.

  28. Louis II says:

    Did anyone else hear music from Apocalypse Now?

  29. ladz says:

    Sounds exactly like the ancient VFD on my lathe. Newer VFDs I think are usually not this noisy.

  30. Olivier says:

    @hanneshow the: I don’t think german police would care what you ride in france…

    Some years ago, peugeot made an electric scooter. I saw only one on the road, but this thing was really dangerous: it was almost silent and you couldn’t really see it arriving :-/ Scooters and bikes must be loud for our security.

  31. anitokyo says:

    Damn! I think I should be making one. That doesn’t have a reverse button which is like those kiddie toy bikes. :D

  32. phugh says:

    Nice. This power transmission setup would also work nicely for a trike, as it does have reverse. Trikes are lower so they are much easier to streamline. More space for batteries too.

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