voltage doubeler with capacitors

Discussion in 'General Electronics Chat' started by ripadisc, Aug 31, 2016.

  1. ripadisc

    Thread Starter New Member

    Aug 31, 2016
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    Hey guys trying to double my voltage from 24 to around 48v to run a grid tie inverter can this be done with capacitors
     
  2. crutschow

    Expert

    Mar 14, 2008
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    How much current?
    Capacitive voltage doublers only work well for small currents.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
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    ................unless you use really huge capacitors and a high frequency drive waveform.
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    ... and are prepared to have very low efficiency.
     
  5. ian field

    Distinguished Member

    Oct 27, 2012
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    The triplers in TV sets didn't run particularly hot - the diodes in the early ones were long paxolin tubes full of hundreds of little selenium rectifier pellets.

    They're not inefficient if you design them properly.

    A double charge pump used to be the favourite method to make dual voltage SMPSU rectifier/reservoir circuits - they didn't run particularly any hotter than just a bridge rectifier charging the reservoir.
     
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I meant that in the way of this conundrum http://www.smpstech.com/charge.htm In the first picture lets say you have 1F at 1v which is 0.5J of total energy, but after the switch closes you get twice 1F at 0.5V = 0.125J so total energy of 0.25J. When you charge a capacitor by paralleling it with another capacitor, you lose half or less of the energy in the resistance.
    That is also why step down SMPS uses an inductor as well as acapacitor, instead of just doing PWM into a capacitive load.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    In most SMPSU topologies - the output side capacitor has nothing to do with conversion, its simply a LPF.
     
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