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h bridge motor controllers

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by bob golding, Mar 3, 2022.

  1. bob golding

    bob golding Member Gold Contributor

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    hi all,
    after months getting my pc up to a decent standard to use with my hp reverb goggles i am getting ready to start on the platform build. i have got hold of a couple of wheelchair motors cheaply to do some experiments before i jump in with the build. i have a local enginner who will any welding and machineing needed so its testing time. i have looked at the few h bridges but a bit of feedback based on experiance would be useful. the motors are 330 watt 24 volt. don't know about the final drive speed yet as i haven't tested them.
  2. Ads Master

    Ads Master

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  3. SaintFrank

    SaintFrank Member

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    Hi, I use IBT-2 (BTS7960 5.5V naar 27V 43A High Power Motor Driver)
    bridges with 250W 24Volt wheelchair motors .
    I'm still building and testing my rig .
    But the bridges work perfectly , stay cool and are cheap.
    Should be good for 300W motors as well
    Last edited: Mar 5, 2022
  4. 29ford

    29ford New Member

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    Ive got 520W 24v wheel chair motors

    The IBT2s contain the BTS7960 seem to be running them fine although only on bench test at the moment :)
  5. bob golding

    bob golding Member Gold Contributor

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    thanks have ordered a couple. do you know the average current draw of the 2 motor over say a one hour flight. so i can get an idea of the power requirments.
  6. SaintFrank

    SaintFrank Member

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  7. bob golding

    bob golding Member Gold Contributor

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    been offered a large 3 kw meanwell psu. could i run multiple motor controllers from one large psu ok. its over the top but the right price so i would like to run 6 motors controllers from it. eventually. 6 250 watt motors at full load would be 1500 watts so well within its capacity.
  8. bob golding

    bob golding Member Gold Contributor

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    i may have found a suitable power supply,and have ordered some h bridge controllers. one thing that has occured to me is whether i need to add any protection circuitry against back emf from the motors. as the motors are reversing all time this may be difficult,is it needed i wonder?
  9. SaintFrank

    SaintFrank Member

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    I have no experience with powering 6 motors, but it is powerfull enough:D
  10. bob golding

    bob golding Member Gold Contributor

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    doi need to add diodes the hbridges to prevent back emf when the motor is running in reverse.? oe does the software k
    looking good.i have got my power supply. bit over top but the right price. meanwell rps 3000. 3 kw at 24 volts. 125 amps. i like your motors. have been looking at electric scooter motors whick look a lot like those. i have got some h bridges and a couple of wheelchair motors that i have yet it test. still got a long way to go but getting the bits together slowly. wondeing if your base twists as it doesnt see to have any cross support. the mini seat looks good. will have to go the scrapyard and find one,plus a uj as well.
  11. SaintFrank

    SaintFrank Member

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    The base is stirdy no twist movement at all , what do you mean with a cross support.
    I got some trouble with backlash in the motors , need to put some (gas) springs on it .

    good luck with the build , will be following your progress
  12. 2nasty4u

    2nasty4u ROOKIE BUT LEARNING FAST Gold Contributor

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    They should already be protected bro because that's what they're made to do they're made to run and Reverse Motors multiple motors at a time so they're they're made to do that so they should be already protected
    • Informative Informative x 1
  13. cx5my

    cx5my Member Gold Contributor

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    Thanks, I'm glad someone else, i.e. you confirm this.......

    Hence whatever problems we are facing is not about "reverse motion voltage", but something else entirely.
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  14. cx5my

    cx5my Member Gold Contributor

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    Hi Bob,

    Back EMF in lay men term is efficientcy lost "during" operation, not voltage generated when motor is manually pushed/spin by hand or the sim-rig falls from sky to ground.

    i.e. back emf, using a different way of saying, is something like example ==> we provide 10v into motor, but motor's internally produces back emf (naturally must happens, it's law of physics), hence let's assume the back emf is 5v large just for the sake of making this example, ultimately the motor is only spining forward 10v mins 5v = real spinning only 5v.

    back emf stops instantaneously hence motor stop, irregardless forward or backward by input voltage source, AND irregardless forward or backward by manually pushed/turning the spindle.

    i.e. when we turn the spindle by hand, the motor generates voltage, this is not back emf, and I see you want to protect against this, but I think the circuit design of H-bridges already can handle this, I would think it must because it know there will be time exposure from reverse voltage.

    last, when we turn the spingle by hand, the faster we do it, the stronger the resistance we feel, this resistance is back emf, i.e. lost of efficientcy.

    There's many youtube of EV motor's design, how they figure out how to reduce the back EMF and push the boundary of motor design, now it's around 85% efficient for EV, high-spec / latest EV. For cheap DC motors, I think may be only 50% efficient ......

    Correct me if I'm wrong, anyone, thanks.
  15. Steve B

    Steve B Member Gold Contributor

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    Some insight into IBT-2 H-bridges, they seem to be designed to be powered by batteries and so the power generated by the motor on deceleration which would be directed to a braking resistor on more expensive controllers is pushed back to the power supply and raises the supply voltage for a fraction of a second.
    This may not be an issue, however if your power supply has over voltage protection of may shutdown.
    Also if the voltage gets too high the IBT-2 may fail, they are usually listed as max 27v.

    A high powered diode between the power supply and H-bridges will protect the power supply and prevent that shutting down.
  16. 2nasty4u

    2nasty4u ROOKIE BUT LEARNING FAST Gold Contributor

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    Do you have a recommendation on which diode to use and what line to connect it to?
  17. 2nasty4u

    2nasty4u ROOKIE BUT LEARNING FAST Gold Contributor

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    Yes