Post by thread:[EE]:: Inductive power transfer over 1 metre + at

Much rubbish is written about IPT (Inductive Power Transfer) and many patents seem to be trying to endlessly reinvent things that Tesla played with. Or Prof Don Otto ** :-). BUT it seems like Stanford may have found a way of increasing the range over which very high efficiency transfer can be achieved Their examples show transfer of around 97% efficiency at ranges of about 1 metre and somewhat more than 80% at 3 metres. See figure 4 in the free access paper below. Their "enabling technology" appears to be "metallic planes" behind the coils relative to an axis running between the coils. I've only glanced at the paper so far but it looks promising - with the best efficiency topology also being the most convenient one for many applications. http://www.stanford.edu/group/fan/publication/Yu_APL_99_214102_2011.pdf It does appear at first glance * as if they may be reinventing a near-field version of the Yagi-Uda antenna, in which case their patents may be somewhat shaky. http://en.wikipedia.org/wiki/Yagi-Uda_antenna Automotive on-highway recharging using this technique http://www.gizmag.com/stanford-wireless-ev-charging/21321/?utm_source=Gizmag+Subscribers&utm_campaign=4686329cac-UA-2235360-4&utm_medium=email ____________________ ** 1971 IPT work - the late Don Otto, Auckalnd University. http://en.wikipedia.org/wiki/Wireless_energy_transfer Says: ** 1971: Prof. Don Otto develops a small trolley powered by induction at The University of Auckland, in New Zealand.[citation needed] I "drove" it at one stage :-) Russell McMahon Applied Technology ltd ___________________________ * proper reading may show this impression to be wrong

13.56 MHz ISM band is close and the next two harmonics are also ISM. But transmitting power at that frequency might keep my RFID access card from working :( Cheerful regards, Bob On Tue, Feb 7, 2012, at 05:27 AM, John Gardner wrote: > At 10 MHz 97% efficiency may not be enough to wave off FCC > black helicopters... -- http://www.fastmail.fm - Email service worth paying for. Try it for free

Actually it's the electric field which is being transmitted, not magnetic field. On Tue, Feb 7, 2012 at 3:32 PM, RussellMc <.....apptechnzKILLspam@spam@gmail.com> wrote: > On 8 February 2012 02:27, John Gardner <goflo3KILLspamgmail.com> wrote: >> >> At 10 MHz 97% efficiency may not be enough to wave off FCC >> black helicopters... > > > Near Field / magnetic is the intention. > Keeping it that way is the trick. > > > Russell > >

The Stanford paper clearly says" "Power transfer between the resonators occurs in the near-field regime through the magnetic field. The use of magnetic field as the coupling mechanism is important for safety reasons and also minimizes interference effect by off-resonant external dielectric objects." On Tue, Feb 7, 2012 at 10:37 AM, Yigit Turgut <.....y.turgutKILLspam.....gmail.com> wrote: > Actually it's the electric field which is being transmitted, not magnetic > field. >

I was referring to the original work of Tesla. On Tue, Feb 7, 2012 at 9:30 PM, Robert Rolf <EraseMERobert.Rolfspam_OUTTakeThisOuTualberta.ca> wrote: > The Stanford paper clearly says" > > "Power transfer > between the resonators occurs in the near-field regime through > the magnetic field. The use of magnetic field as the coupling > mechanism is important for safety reasons and also minimizes > interference effect by off-resonant external dielectric objects." > > On Tue, Feb 7, 2012 at 10:37 AM, Yigit Turgut <y.turgutspam_OUTgmail.com> wrote: > >> Actually it's the electric field which is being transmitted, not magnetic >> field. >> >> >