Re: Solid-state TC - transformer design

To: tesla-at-pupman-dot-com
Subject: Re: Solid-state TC - transformer design
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
Date: Fri, 25 Oct 1996 08:12:28 +1200

Alan, in reply....

> One dumb question - leakage induction. I'm assuming that the primary
> acts partly like a pure transformer perfectly coupled to the secondary.
> But partly like a pure inductor blind to the secondary. And of course
> partly as a pure resistor boiling off the enamel :(. So the effect of the
> leakage induction is then to resist the rise in current and to give
> back EMF at switch off. Is this right?

Leakage inductance is modelled as an inductor completely separate 
from and uncoupled to the transformer. This inductor can be seen
in both primary and secondary and has a value reflecting the turns 
ratio when looking into the appropriate winding. If one models it 
that way, it is then a component capable of storing 0.5LI^2 which
is basically a rogue lump of energy. If you short one of the windings
then measure the inductance of the other winding, you are measuring 
the leakage inductance (uncoupled flux). A perfect transformer will
theoretically give zero inductance in this situation. I think I got 
that right but stand to be corrected.

Malcolm