Re: Energy storage in primary?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Jolyon,

The quenching switch (SW2) should have the same low ON voltage as the main 
current interrupting switch (SW1). The sequence of operation would be to 
close SW1 and SW2, allowing primary current to build to the desired level 
through SW1. Then open SW1, allowing the primary LC circuit to ring 
(through SW2), beginning energy transfer to the secondary. Once all of the 
primary's initial bang energy (0.5 Lp(Ip^2)) has been transferred to the 
secondary, open SW2. Although a self-commutating SCR, bridged with a 
reversed diode to permit reverse conduction, might be cobbled up, a better 
choice for SW2 would likely be an IGBT or power MOSFET. And yes, connecting 
SW2 in series with C1 to ground would simplify biasing of SW2. Using a 
monostable to provide control for SW2 would work (nice and simple), or one 
could detect the point of minimum primary energy or maximum secondary 
energy (providing more flexibility).

Best regards,

-- Bert --
-- 
Bert Hickman
"Electromagically" (TM) Shrunken Coins
Stoneridge Engineering's Teslamania
http://www.teslamania-dot-com

Tesla list wrote:
>Original poster: "Jolyon Vater Cox by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>It is strange but it it seems the requirements of the quenching switch
>(which I shall term SW2) -that it should turn off below an extinction
>voltage, or after a set period of time are exactly the same as those
>respectively for a static and a rotary spark gap;both of which I presume
>would be unsuitable in this instance due to the relatively low voltage of
>the current-driven primary.
>Other than saturating reactors what if any are the other possible options
>for quenching in a current-driven TC?
>Would the best position for the quench switch to be connected be between the
>lower lead of C1 and the ground rail?
>For the voltage-controlled quench, would DIACs, neon bulbs, or
>thyristors/TRIACs triggered by zeners or neon bulbs be of any use?
>Or, for a time-controlled quench would it be possible to used a monostable
>(another 555?) to gate SW2, which would close the moment the first switch,
>SW1, opened.
>The quench switch would turn on for a period of time less than the "off"
>period of SW1, terminating the flow of current in the primary-capacitor loop
>after the timed period elapsed. The monostable would be triggered by the
>falling edge of the squarewave from the astable.
>Would any of these ideas work?
>Jolyon.
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Thursday, January 30, 2003 7:23 AM
>Subject: Re: Energy storage in primary?
>
>  > Original poster: "Bert Hickman by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
>  >
>  > Hi Jolyon,
>  >
>  > My response is interspersed below...
>  >
>  > Tesla list wrote:
>  > >Original poster: "Jolyon Vater Cox by way of Terry Fritz
>  > ><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>  > >So the primary oscillation will not be quenched when the switch turns on
>  > >again -short-circuiting the primary capacitor?
>  >
>  > The goal of quenching is to strand energy in the secondary side at the
>  > appropriate time by opening the primary LC current loop. If we short
>  > circuited the primary capacitor instead, this has the effect of short
>  > circuiting the primary inductor, but it still leaves the primary as an
>  > "active" element in the primary-secondary magnetic circuit. The primary
>  > would behave as a short circuited transformer winding, robbing energy from
>  > the secondary resonator. To achieve a proper quench, the primary current
>  > loop must be broken.
>  >
>  >
>  > >Could quenching be accomplished  by means of saturating ferrite core in
>  > >series with the TC primary- these have a  high impedance to current
>changes
>  > >at low voltage but low impedance to current changes at higher
>voltage -when
>  > >the core saturates.
>  >
>  > Interesting question... this might work. However, Including a nonlinear
>  > off-axis inductive element in the LC loop may also create additional
>  > voltage standoff problems for the main switch when the inductor goes in
>and
>  > out of saturation, and interesting tuning characteristics... :^)
>  >
>  > >Jolyon
>  >
>  > Best regards,
>  >
>  > -- Bert --
>  > --
>  > Bert Hickman
>  > "Electromagically" (TM) Shrunken Coins
>  > Stoneridge Engineering's Teslamania
>  > http://www.teslamania-dot-com
>  >
>  > >----- Original Message -----
>  > >From: "Tesla list" <tesla-at-pupman-dot-com>
>  > >To: <tesla-at-pupman-dot-com>
>  > >Sent: Tuesday, January 28, 2003 7:20 PM
>  > >Subject: Re: Energy storage in primary?
>  > >
>  > >  > Original poster: "Bert Hickman by way of Terry Fritz
>  > ><teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
>  > >  >
>  > >  > Jolyon,
>  > >  >
>  > >  > In theory, yes. However, in practice, it's difficult to find an
>"opening
>  > >  > switch" that can handle high current and then quickly be able to
>withstand
>  > >  > the subsequent high voltage developed across the inductor. Some
>pulsed
>  > >  > power systems have been successfully designed to use energy initially
>  > >  > stored in inductors (quite desirable, since inductors can store
>msnip.....