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Thread: Hub motor repair

              
   
   
  1. #21
    teddillard
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    Quote Originally Posted by DRZ400 View Post
    Here is the controller I bought....hall sensor or sensorless works great. Brake, cruise control, rpm out. Several guys on ES use them. Some have swapped out the 12 drive fets to IRF units (low (RDSon) to boost the output.

    http://cgi.ebay.com/ebaymotors/500W-...item1c0cb61e25
    I'm really confused. These will work on a motor that's designed for Hall sensors, but without the Hall sensors? How does it work?

  2. #22
    Not to be taken seriously DaveAK's Avatar
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    $5 a piece? You could get all three from mouser.com for less than that, (see my link). Also from DigiKey I would have thought. Maybe you're going for extra special ones.

  3. #23
    teddillard
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    yeah David emailed me today with a price around $1.50- more like it. The $5 price was Digikey I think. I'm going to update tomorrow though, he set up a test pad and we tested them all outside of the motor- they tested out fine. Next dissection is the controller...

    IMG_3023.JPG

    update: Basically David was not confident that we were getting good test results the way we were trying to do it. Sitting on the couch, holding several leads together, resistors in series and all that. He put together the little test rig shown above and tried it out with some sensors he had lying around, and it was really easy to see what was going on. I'm honestly not sure exactly how it is set up, but there are resistors in the circuit and the LED apparently provides some load. If anyone's interested maybe I can get him to shoot me a diagram, but I think you can figure it out from what Rob posted above.

    The end result is that they are "latching" sensors- they turn on and stay on until they're turned off - and all three work fine.
    Last edited by teddillard; 28 October 2010 at 0323.

  4. #24
    SMPS Engineer BaldBruce's Avatar
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    Quote Originally Posted by teddillard View Post
    I'm really confused. These will work on a motor that's designed for Hall sensors, but without the Hall sensors? How does it work?
    Sensorless inverters work by infering the position from the voltage signal directly off the drive wires rather than seperate sensors. They either look at the third leg while driving the other two if it is a two phase at a time type or they can measure the back emf on all three to infer the position of the rotor. This type of controller could care less if you originally had sensors, the more compicated circuit internal to the controller makes the sensor unnecesary.
    I have not failed. I've just found 10,000 ways that won't work.
    Thomas A. Edison

  5. #25
    teddillard
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    Quote Originally Posted by BaldBruce View Post
    Sensorless inverters work by infering the position from the voltage signal directly off the drive wires rather than seperate sensors. They either look at the third leg while driving the other two if it is a two phase at a time type or they can measure the back emf on all three to infer the position of the rotor. This type of controller could care less if you originally had sensors, the more compicated circuit internal to the controller makes the sensor unnecesary.
    Wow, cool. I poked around ES a bit and read up on them... seems like a great option. I'm wondering about the China ordering on Ebay, though- last item I ordered from China took 6 months to arrive. Did you have better luck, DRZ400? (Shipping is almost as much as the item, too- $24- at $50 total or so, it's almost the same price as the stock replacement...)

    I also noticed on one site it says the sensored version of a controller was "instant start" where the sensorless was "pedal first". Any info on that? Are all sensorless needing to be spun up first, or was that just that particular model?

    Sounds like it'd be a fun little twist on the project...
    Last edited by teddillard; 28 October 2010 at 0354.

  6. #26
    Senior Member SplinterOz's Avatar
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    Sensorless controllers have to guess he position of the motor if the motor is stationary. Most sensorless controllers will "shudder" a little at startup as they determine which phase to power to get the motor moving. Also they also they tend to blow the power circuit if the motor does not move immediately.

  7. #27
    Senior Member DRZ400's Avatar
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    I tried mine both with and without sensors....just as smooth either way. I've used sensorless for over 9 months now....ALL of my 10 R/C brushless planes and helis are sensorless as well....nothing new really as hall sensors have not been used in over 10 years in RC. I got mine in 5 days from China, I think it was fed-x. It works very well and is dirt cheap.....with a simple FET upgrade you could easily double the power handling if needed.
    2003 Ninja 250EX, Agni #95R, 6:1 Gearing, 11 Leaf Modules.
    Alltrax SPM72400, 400 amp Controller, all LED lighting
    2014 CRF450X Supermoto
    http://www.evalbum.com/1955
    http://www.evalbum.com/3337

  8. #28
    Senior Member SplinterOz's Avatar
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    I know RC planes and Heli's use them all the time. They are ideal for that for a few reasons. One of the big ones is that they have virtually no load on the motor at start up. However EV's have most load at startup.

    I have heard that the newer sensorless controllers are smother and I am getting one to test for my build as soon as they build one that can do 72volts and 200amps for me.

  9. #29
    teddillard
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    Quote Originally Posted by SplinterOz View Post
    However EV's have most load at startup.
    Especially when you're doing burnouts...

    Since the sensors seem OK, I'm tearing into the controller. Here's the guts:



    I don't see anything melty or anything, but Mr. Wizard might...

  10. #30
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    Hi Rob,
    I was really impressed by your experience and knowlege. So I am encouraged to ask you about my bike. I bought it from China a week ago. it is 72 V 1500 wats .It worked well... for one day. I tried to drain the batteries to test the limits of the scooter, and after the voltage felt under 62 V the motor stopped, and never started again. I changed all the fuses, I ordered a new contrller, but nothing happens. The voltmeter on the screen reads 79 Volts, the lights, horn are OK, but the motor only slightli ckliks when i twist the throttle. Please advise.
    Quote Originally Posted by magicsmoke View Post
    It's my job Ted, it's how I eat.
    If I was paid for my photography Knowledge I'd be on elsoupkitchen.net

    Harlan, that looks like a cool mod. Any chance you could detail it in a thread?

    Rob

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