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PIEZOELECTIRC ENERGY HARVESTING SYSTEM WITH FREQUENCY MISMATCH TOLERANCE

  • US 20160204717A1
  • Filed: 02/16/2015
  • Published: 07/14/2016
  • Est. Priority Date: 01/09/2015
  • Status: Active Grant
First Claim
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1. An impedance matching circuit, for use with a piezotransducer that can produce an output voltage waveform in response to a mechanical input stimulus and with an energy storage circuit that can harvest energy from the output voltage waveform, wherein the piezotransducer includes a parasitic capacitor, the impedance matching circuit comprising:

  • an inductor configured to be coupled in parallel with the parasitic capacitor;

    a peak and valley detection circuit configured to detect output voltage waveform peaks and valleys;

    a first switch circuit configured to bias flip the output voltage waveform at a selectable first time relative to a detected peak and at a selectable first time relative to a detected valley;

    a second switch circuit configured to couple the inductor to the energy storage circuit at a selectable second time following each output voltage bias flip;

    an energy monitoring circuit that includes a voltage detector configured to provide an indication of energy flow from the inductor to the energy storage circuit following each output voltage bias flip; and

    a maximum power point tracking (MPPT) circuit configured to select the first time and the second time based at least in part upon the indicated energy flow.

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