Re: [femm] Inductance by means of his definition

[dcm3c@xxxxxxx]

In a message dated 11/15/01 8:00:21 AM Eastern Standard Time, albertoperarnau@xxxxxxxx writes:


> Hello,
> As you know I'm simulating an induction motor, now I'm calculating inductance. I read manual of femm where it says to calculate inductance by energy. I use this method, but I find another method where it uses integer of A, the equation is:
>  
>  L = [N*h/Scopper*(integer A in section Scopper+ - integer A in section Scopper- )]/i
> where
> N : number of turns
> h : depth 
> Scopper : section 
> i: current 
>  


I think that this oughta be:

L=(N*h*Scopper/i) * (A1 - A2)

where A1 is the average value of a in section Scopper+ 
and A2 is the average value of a in section Scopper-

W
> hich method is more exact or are two equals? I think this method is more exact because  the method of energy uses definition of W=1/2Li^2 and  it equals to energy by integer of AJ. This method come of definition of inductance. The results are similars by two methods.
>  
> Thank you
>  
> Alberto


It's neither more nor less accurate than using a energy method, because you can show that it really is the A.J integral method for the special case where the current in the coil cross-section is constant.
--
David Meeker
http://members.aol.com/_ht_a/dcm3c