Synchronous Rectifier for an Energy Harvester

Discussion in 'The Projects Forum' started by BBB, Jan 13, 2010.

  1. BBB

    Thread Starter New Member

    Jan 13, 2010
    8
    0
    Hi everyone,

    I have a kinetic energy harvesting device which, when moved around produces a varying voltage amplitude in the order of 200mV and current in the order of nanoamps.

    I would like to convert this into useful energy (i.e. a DC voltage) and therefore have looked into building a synchronous rectifier with the use of schottky diodes, mosfets and op-amp comparators. I have attached the schematic of what I want to do.

    The problem I am having is, I'm not sure if it is possible to get such low ratings on the components, do I need some kind of boost converter first? I would like to build it on a breadboard / verroboard and people I have seen who have done this are fabricating it on silicon which obviously I am no able to do. Any help would be much appreciated.

    Cheers
     
  2. 3ldon

    Active Member

    Jan 9, 2010
    82
    3
    (Vx10^-1)*(Ax10^-9)= Wx10^-10

    this is not usable power. discrete silicon components require microamps at best.
     
  3. BBB

    Thread Starter New Member

    Jan 13, 2010
    8
    0
    ok, if we assume the harvester produces microwatts 10^-6W. Can this be done?
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,535
    The problem, as I see it, is you have to power the components that will harvest the power first. Like a glutton at a buffet, it will eat up your profits.

    If your hypothetical power source was low voltage high current then you might be able to get somewhere. The real measure of practicality is available wattage. How many watts do you think you'll need to power up those op amps? MOSFETs take a pretty good surge to switch, though they use almost nothing to maintain a state.

    The power levels you have stated don't sound worthwhile. They sound smaller than a crystal radio would produce.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    What would you define as useful energy? Any device that might be able to raise the voltage has to be powered by the same energy that gets harvested.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I think your're going to have to look at different methods of harvesting energy.

    I don't know of any commercially available components that could function with such low power levels.

    You might have a look on the EDN site; there was an article posted perhaps a year ago about using a piezo transducer to charge a supercapacitor using harvested energy.

    Search Google for: piezo energy harvesting
     
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