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Wireless power transfer via variable coupling capacitance

  • US 9,300,163 B2
  • Filed: 03/14/2014
  • Issued: 03/29/2016
  • Est. Priority Date: 03/15/2013
  • Status: Active Grant
First Claim
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1. A system comprising:

  • a charger having;

    a source that provides alternating current at a source frequency (fs), and has a first terminal and a second terminal, and a source impedance;

    a first reactive component connected between said first terminal and an interim point;

    a second reactive component connected between said interim point and said second terminal,wherein one of said first reactive component and said second reactive component is a capacitor, and the other of said first reactive component and said second reactive component is a first inductor,wherein said first reactive component, said second reactive component, and said source impedance, in combination, have a Thé

    venin equivalent impedance,wherein said first inductor and said capacitor have a resonant frequency that is different from said source frequency;

    a first plate that is electrically conductive;

    a second inductor connected between said interim point and said first plate; and

    a second plate that is electrically conductive and is connected to said second terminal; and

    a portable device having;

    a third plate that faces said first plate, wherein said third plate is electrically conductive and thus forms a first capacitance between said third plate and said first plate;

    a fourth plate that faces said second plate, wherein said fourth plate is electrically conductive and thus forms a second capacitance between said second plate and said fourth plate; and

    an electrical load resistance connected between said third plate and fourth plate,wherein said first and second capacitances, together, have an equivalent series capacitance,wherein said equivalent series capacitance has a value in a range between an initial value and 60% of said initial value,wherein said Thé

    venin equivalent impedance has a positive imaginary component, and a magnitude that is at least three times greater than said load resistance,wherein said second inductor has a reactance approximately equal to a reactance of said initial value of said equivalent series capacitance.

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