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How does wireless charging works?

Discussion in 'Electronic Design' started by [email protected], Jun 2, 2013.

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  1. Guest

    Hello there,

    I live in India, currently studying electronics..

    I would love to learn and create on of wireless charges for mobile phone like Nexus and samsung.

    May anybody please tell me guide , basic info and instruction to pursue my journey?
     
  2. Jamie

    Jamie Guest

    School projects must be in again.

    http://en.wikipedia.org/wiki/Helmholtz_coil

    Jamie
     
  3. Percival

    Percival Guest

    It's basically transformer technology with the primary winding in the
    charger and the secondary winding (and rectifiers and other conditioning
    circuitry) in the device being charged.

    Transformers can be better than 99% efficient but that assumes very
    close coupling between primary and secondary, so most "wireless" systems
    use "tricks" like running at high frequency and making both windings
    resonant at that frequency to cut losses.

    This is (unusually for Wikipedia) a pretty good overview of the topic:

    http://en.wikipedia.org/wiki/Inductive_charging

    I always recommend taking what Wikipedia says with a grain of salt,
    and checking the listed references and external links at the end for
    more in-depth information.


    Mark L. Fergerson
     
  4. G. Morgan

    G. Morgan Guest

    Induction.
     
  5. Robert Macy

    Robert Macy Guest

    select operating frequency on the highest [within practical limits,
    skin effect will eat you alive] allowed by regulatory agency, probably
    9.999kHz, but you may be able to go up as high as near 150kHz..

    For the Tx, think 'make a field' related to diameter AND current.
    Sometimes tuning the Tx makes high current easier, too.
    For the Rx, think intercept as much field as possible and 'high Q
    tuned to resonate' related to accessible energy 'tapping' that energy,
    when I say high Q, I mean at least 150, probably more than 200. If you
    can get 400-600, celebrate!

    You'll find that large diameter, closely coupled coils work the best.
    Foget using any metal - no advantage and usually gets in the way.

    Remember magnetic fields are a bit like sound in that once created
    they are difficult to get rid of. They penetrate, reflect, and bounce
    everywhere. But there in lies an advantage too. The penetrate means
    the Rx coil can be hidden. Reflect means the energy is around
    somewhere.

    For receiver regulation think in terms of LOW impedance, not HIGH
    impedance. So to shut off the spigot of power coming in, you SHORT the
    input, do not OPEN the input like you do with a voltage power supply.
    For example, if you want to lower power coming in from the Rx coil,
    place an impedance across the coil, de-Q'ing the receiver and you'll
    get less power. Short the coil completely and in a loosely coupled
    transformer system; you'll get almost NO power. If in trying to lower
    power you instead try opening up the receiver system, you'll find some
    excitingly HIGH voltages! The concepts are reversed of what we're use
    to, so simply turn your thinking 'inside out'.

    To optimize components and structures, use femm 4.2, octave, and
    LTspice [all free software tools] Don't know how to use each? join
    their groups, they are VERY helpful.

    There are more 'tricks' but you'll learn those as you proceed.

    When you're done, share what you learned and ship one to Jim Thompson
    for his phone and I'll consider my 'consulting fee' paid.. ;)
     
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