Re: eddy current brake

["David Meeker" <dmeeker@xxxxxxxx>]

--- In femm@xxxxxxxxxxxxxxx, "mvalca" <mvalca@xxxx> wrote:
> Hello everybody, 
> I am looking for some basic theory of eddy current brake, can anybody 
> suggest to me a site with those informations? I am interested mainly 
> on some simple problem exactly solved.
> 
> thank you
> 
> Marco

I don't really know of a good _simple_ explanation of eddy current
brakes. Although the mechanism by which they work is somewhat
intuitive, the mathematical description of them can be nontrivial.

Anyhow, I like to think of eddy current brakes as being like induction
motors--you could get a lot of insight into eddy current brakes by
thinking of them in that way. An eddy current brake would be the
special case of an induction motor in which the applied frequency is
zero (i.e. DC currents are flowing in the windings of the machine).

I also had some note that I wrote a while ago "for fun" that describes
how one would obtain a closed-form expression for the force produced
by a particular configuration of linear eddy current brake. Since the
answers are analytical, it may be possible to glean some intuitive
insight about what's going on, although it's still pretty
mathematical... I've put a copy of this at: 
http://groups.yahoo.com/group/femm/files/halb.pdf
This note is somewhat similiar to the recent paper:
Spok-Myeong Jang, Sung-Ho Lee, and Sang-Sub Jeong, "Characteristic
analysis of eddy-current brake system using the linear Halbach array",
IEEE Transactions on Magnetics, 38(5):2994-2996, September 2002.

Dave.