Re: Wireless Recharging For Electric Cars

larry moe 'n curly <larrymoencurly@xxxxxxxxxxx> wrote:
Scott Dorsey wrote:

Don Stauffer <stauffer@xxxxxxxxxxxx> wrote:

jolly wrote:
Nissan Plans Wireless Charging on Electric Cars
http://www.techespot.com/2009/08/electric-cars-wireless-recharging-for.html

Those coils need to be VERY close to maintain efficiency. Also, the
fringe magnetic field (that not coupled well) is likely to be VERY
strong. Don't get any piece of electronics in that area!

Depends. The key is that the coils need to be physically touching... the
amount of loss with even a tiny gap is very, very substantial.

So why don't the coils touch in any transformer? OTOH the parts of
the core do touch.

What actually needs to touch are the cores of the two coils. In the
case of a standard transformer, they're wound on a single coil.

What you're doing here is you are constructing a split-core transformer,
that comes apart into two halves. One half is in the car and the other
is at the gas station.

If there is a lot of DC on a transformer primary or secondary, the
core can get saturated, and the solution to this is to cut a notch
in the coil to make it lossy. It only takes a tiny notch to blow
the efficiency at low frequencies to hell. So you want to avoid
doing this on a power transformer at all costs.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
.

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