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DRV8301 and super capacitors

John Tzortzis
Prodigy 90 points
Other Parts Discussed in Thread: DRV8312, DRV8301

Hello,

i am member of a team and we are working on a regenerative braking project using super capacitors. We use the drv8301 kit to control our BLDC motor. Our tests were successfully completed by using LiPo batteries, but when we tried to power the kit with super capacitors, we figured out that the motor could not raises over 400 revs. The capacitors were charged on 12-13 Volts and we thought that it was the problem, because in another post Mr. Chris Clearman said that  "Are you using 14.8V for the bus?  I know the DRV8301 kit doesn't like a bus voltage that low unless you supply the 5V separately to J2" . But we tried to power the kit with one LiPo battery charged on same Volts and everything was ok. So what is the problem of our system? Will the problem get solved if we supply 5V separately to J2?

Thank you in advance,

John

  • 0
    TI__Mastermind 21320 points

    Hi John,

    What do mean by could not raise over 400 revs? Is there a power limitation to the super capacitors. Can you measure the output of the buck converter when the super capacitors are used as the power supply.

    I don't believe the 5V should be an issue. I think Chris may have been refering to the DRV8312 kit.

  • 0 in reply to Nicholas Oborny
    TI__Guru** 119500 points

    I think if you were having an issue with this voltage you would see a brown out / reset event. That's what I see on the DRV8301 EVM at too low of voltage. This doesn't happen on the DRV8301 BOOST, so I think it just has to do with the 12V regulator on the EVM.

    You can try supplying this voltage instead of taking it from the bus...but you didn't see this with the LiPo....

    On your super cap, I assume there is no issue with how fast current can be pulled?  And the voltage is stable or does it droop?

     

  • 0 in reply to ChrisClearman
    Prodigy 90 points

    Hello,

    thank you for your fast replies. Finally we figured out that the problem was the compiler  c2000_6.2.0. We install c2000_6.2.3 and now everything is working perfect.

    Thank you for you time.

  • 0 in reply to John Tzortzis
    Prodigy 90 points

    Hello again,

    we have build a charging cirquit (dc/dc converter) for the purposes of the regenerative braking system we are working on. The system:

         Motor -->  charging cirquit --> supercaps

    So we manually spin the motor to charge the super capacitors. I would like to ask if we could use the DRV8301-69M-KIT instead of our charging cirquit. I know that DRV8301-69M-KIT contains buck converter, 3-phase mosfet driver etc, so i thought that it may be possible to be used as a charger for the super capacitors.

    Thank you in advance,

    John

  • 0 in reply to John Tzortzis
    TI__Guru** 119500 points

    Your comment about the buck converter has confused me...the buck is simply:
    Vdcbus - DRV8301 Buck - 3.3V out to power MCU.
    I don't see this being used specifically for anything to do with your super caps.

    I understand you want to charge super caps, and for that you need a voltage and current source.  For regenerative braking this means you are getting this from an electric motor during it's non-motoring phase (energy is leaving the motor, not being consumed by the motor in the form of torque + heat production).

    Certainly the motor when controlled by InstaSPIN-FOC or -MOTION can operate in generating mode, and voltage/current will be supplied back to the bus....and you can use your circuit to charge your caps.

     

  • 0 in reply to ChrisClearman
    Prodigy 90 points

    Hi Chris,

      thank you for your reply. My comment about the buck converter was just silly. The most important is that the voltage/current can be supplied back to the bus. I tried it and everything was ok. Your answer was very helpful.

    John.