Connect with us

Regenerative braking

Discussion in 'General Electronics Discussion' started by cdog, Feb 19, 2012.

Scroll to continue with content
  1. cdog

    cdog

    7
    0
    Feb 19, 2012

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    My first thought is that the 4082 may not be able to supply enough current to switch the mosfets very quickly. This will cause problems with heating of the mosfets.

    The second problem is, if you use the correct drivers, the switching speed will be much higher and you will need to worry about dead time to ensure that you don't have problems with shoot-through (which will cause rapid death of your mosfets)

    I haven't bothered to look further in your circuit than that.
     
  3. cdog

    cdog

    7
    0
    Feb 19, 2012
    Thanks for taking the time to look Steve.
    The bootstrap cap values are lifted directly from the Harris datasheet, but I agree that the 12v sub-supply needs to be beefier. This variant of the 4080 series claims to be ALMOST shoot-through proof, which is the main reason for choosing it.
    And I belive in Father Christmas!
    Cheers mate. Any input gratefully recieved. cdog
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    Hahaha, OK, I looked up 4082 and came up with (naturally) a 4000 series CMOS logic chip. Your handwritten IC name appeared to (at first glance) be a common prefix to 4000 series ICs :)

    I'm not familiar with this chip, but looking at the specs, it neatly answers all of my criticisms above.

    I do wonder how Q1 and Q2 can get turned on if Q4 or Q3 are also turned on. I note that this chip does not have a charge pump, so I can't see how it can raise the gate voltage high enough.
     
  5. cdog

    cdog

    7
    0
    Feb 19, 2012
    Hi Steve. It appears that Q1 and Q2 inputs (AHI,BHI) on the chip are both hard-wired high, so I am assuming (!) that some clever switching is going on in there.
    C10 D4, C11 D5 are, (again I assume) the charge-pump components.
    I just cannot work out how to automatically drive a fifth Mosfet to arrange for automatic regenerative braking. Still, thank you for your interest. cdog.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    Why do you need another mosfet?

    You can simply turn on the bottom two mosfets (for dynamic braking) or drive the motor in reverse for regenerative braking.

    For regenerative braking you need to either interpose a diode to only allow a "charging" current, or control the timing such that only a charging current flow (which may be very tricky -- or impossible).

    Do you actually need regenerative braking (i.e. to recover energy) or is dynamic braking. sufficient?
     
  7. cdog

    cdog

    7
    0
    Feb 19, 2012
    No, I personally see no benefit in regeneration on a vehicle such as this, but the faulty commercial unit that I will be replacing has it. Monkey see monkey do.
    As to motor reversal, this will be achieved by VR1, as in forward stop reverse, in the normal usage of the Mobility Scooter (UK term ) cdog
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-