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Re: Charging inductors for resonant charging
Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
Hi Jimmy,
Yeah, I still think it's a problem...
In theory, if the system is operated in a mode where the firing rate is
always at or below 2X the resonant frequency of the charging inductor and
the tank cap, then the inductor the current should return to zero on each
cycle.
In practice, residual magnetism will bias the core since the de-Q'ing diode
prevents reverse current flow, and we begin walking our way into
saturation. Using an ungapped core MIGHT work with if we removed the
de-Q'ing diode AND we set the BPS to 2X the inductor/tank cap resonant
frequency. In this case, reverse current can flow through the inductor for
part of the cycle and this may be sufficient to prevent a saturation problem.
-- Bert --
Tesla list wrote:
>Original poster: jimmy hynes <chunkyboy86-at-yahoo-dot-com>
>You sure? I still think it should work.
>The current will be unidirectional, but the voltage wont, so the current
>wont build up like it
>would with a DC voltage. Most of the flux generated by the secondary will
>just be cancelled out by
>the secondary. The only flux is due to magnetizing current. Since the
>voltage across the primary
>is a sine wave, to find the magnetizing current, it is just V/2*pi*F*L.
>The frequency is probably
>going to be higher than the normal 60hz, so unless you are overvolting it,
>it should be farther
>from saturation. Do you still disagree?
>--- Tesla list <tesla-at-pupman-dot-com> wrote:
> > Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
> >
> > Jimmy,
> >
> > That's why I originally thought it should work. However, because of the
> > de-Q'ing diode in the current path, the charging inductor's current will
> > only be unidirectional, which will drive the ungapped core into
> saturation.
> >
> > -- Bert --
> >
> > Tesla list wrote:
> >
> > >Original poster: jimmy hynes <chunkyboy86-at-yahoo-dot-com>
> > >In a DC resonant charging system, the voltage across the inductor is AC.
> > >The voltage across the
> > >inductor changes polarity when the voltage across the capacitor goes from
> > >< VDC to > VDC. The
> > >transformer should work without a gap, all the energy is stored in
> the low
> > >voltage inductor.
> > >--- Tesla list <tesla-at-pupman-dot-com> wrote:
> > > > Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
> > > >
> > > > Hmmm... you're right! I suppose that's why it sounded too easy!
>:^)
> > > >
> > > > For a DC resonant charging system there appears to be no avoiding
> the need
> > > > for an air gap in the inductor's magnetic circuit. However, if
> the core of
> > > > a moderately sized DT could be cut to introduce an air gap, then this
> > > > approach might still have some merit. The approach would provide
> high BIL
> > > > and current handling and a means to external adjust the charging
> > > inductance
> > > > without resorting to a custom wound inductor. Now, the challenge
> becomes
> > > > how to cleanly cut the core of one of these beasts.
> > > >
> > > > -- Bert --
> > > >
> > > > Tesla list wrote:
> > > >
> > > > >Original poster: "gtyler" <gtyler-at-drummond-dot-org.za>
> > > > >Are you not using this choke on DC? If so the transformer will
> saturate.
> > > > >----- Original Message -----
> > > > >From: "Tesla list" <tesla-at-pupman-dot-com>
> > > > >To: <tesla-at-pupman-dot-com>
> > > > >Sent: Sunday, February 01, 2004 2:57 AM
> > > > >Subject: Re: Charging inductors for resonant charging
> > > > >
> > > > > > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
> > > > > >
> > > > > > Very, very clever... I like it!
> > > > > > One could make a very sophsticated system if one wanted, and
> you'd be
> > > > > > working at "reasonable" voltages
> > > > > > ----- Original Message -----
> > > > > > From: "Tesla list" <tesla-at-pupman-dot-com>
> > > > > > To: <tesla-at-pupman-dot-com>
> > > > > > Sent: Saturday, January 31, 2004 10:25 AM
> > > > > > Subject: Re: Charging inductors for resonant charging
> > > > > >
> > > > > >
> > > > > > > Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
> > > > > > >
> > > > > > > Ed, Jim and all,
> > > > > > >
> > > > > > > Here's an idea I was kicking around with Ed Wingate a
> while back.
> > > > >You
> > > > > > could
> > > > > > > simply use another distribution transformer and ballast
> as a HV
> > > > >charging
> > > > > > > inductor. Use the HV winding in series as the charging
> inductor.
> > > > >Connect
> > > > > > > the low voltage side of the DT to high current ballast
> (welder or
> > > > > > > adjustable high current inductive ballast). The DT will
> multiply
> > > > >the LV
> > > > > > > side ballast inductance by its turns ratio squared,
> easily making
> > > > >the HV
> > > > > > > side look like a large, adjustable, HV inductor. And a
> properly
> > > > >sized DT
> > > > > > > already has the necessary BIL and current rating required.
> > > > > > >
> > > > > > > By selecting the proper distribution transformer and
> ballast, you
> > > > >should
> > > > > > be
> > > > > > > able to get almost infinite flexibility with without the
> need to
> > > > >resort to
> > > > > > > a custom HV choke.
> > > > > > >
> > > > > > > Best regards,
> > > > > > >
> > > > > > > -- Bert --
> > > > > > > --
> > > > >
> > > >
> > > >
> > >
> > >=====
> > >Jimmy
> > >
> > >.
> >