Fuel Cell connected to a super cap

Discussion in 'The Projects Forum' started by gusmas, Mar 3, 2011.

  1. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    Hey guys

    I am doing some research on fuel cells powering a motor and i found a bit of info, I am just curios about the following:

    In pic 1 i found the following:

    1. DC/DC converter acts as a buffer between the fuel cell and energy storage.
    2. The energy storage then acts as the source for the motor.

    If a super capacitor is used. How is the DC motor going to run if the Voltage and current that is being supplied by the super capacitor will decrease with respect to time? Will there be a sensing circuit that will make sure the capacitor is always sitting at around about the level it needs to be to supply enough current to the load?

    Or am I missing something here?
    Last edited: Mar 3, 2011
  2. Adjuster

    Late Member

    Dec 26, 2010
    The motor controller will most probably use switched-mode techniques to provide a variable voltage transformation effect, so that (provided the capacitor voltage stays within certain limits) the motor is given appropriate drive.
  3. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    OK cool I see what you are saying, so for example the motor controller will be able to drive to motor if its "input voltage"(from the super cap) is between 4V and 6V?
  4. Wendy


    Mar 24, 2008
    What kind of fuel cell?
  5. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    hydrogen fuel cell :)
  6. Markd77

    Senior Member

    Sep 7, 2009
    Maybe the fuel cell has a low output current and the supercap is there to provide short periods of higher current.
  7. gusmas

    Thread Starter Active Member

    Sep 27, 2008
    Ok so its been a while so now I am on how to limit the output voltage and current of the fuel cell. Reason for that is firstly to protect againts short circuits since the fuel cell is very expensive and secondly I want to control the max output power of the fuel cell.

    The protection circuitry is not that difficult to imement, the problem is designing a circuit that will only allow a maximum of 24V at 8 amps. Any tips?
  8. GetDeviceInfo

    AAC Fanatic!

    Jun 7, 2009
    I would suggest that the cap is storage for regen action, indicated by the bidirectional arrows.
  9. iONic

    AAC Fanatic!

    Nov 16, 2007
    I tend to agree with GetDeviceInfo. A motor controller is often configured for regenerative action. The fuel cell in the diagram appears to be able to either regenerate the battery source and perhaps also to augment the power to the motor. This would surely increase the longevity of the driving current to the motor. Maybe they can add some solar as well!