Re: Wild Idea OLTC - Split core inductors

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Richard,

At 11:17 PM 8/16/2002 -0400, you wrote:
>
>
>> Richard wrote:
>> 
>> "Replace them with much smaller LC tank circuits tuned to the frequency
>you
>> wish to pass.  Tank R can be held really low and at resonance Z can be
>made
>> zero.  If you play a little with Fo you can get some really interesting
>> band pass filters.  You can make these little LC filters tunable and put
>in
>> as much tank Z as you desire.  Disassemble a flyback core and wind your
>> much smaller inductor.  Don't forget to put the shims back in."
>> 
>> A wild idea I need to look into :-)))
>
>Terry,
>
>Why are these large inductors here in the first place?  What do they do? 

The inductors are resonant with the 47uF primary cap at 60 Hz.  That drives
the 340 peak AC voltage to about 550 volts (could be more with timing tricks).

1 / (2 x pi x SQRT (0.15H x 47uF)  = 60 Hz.

>They do form an LC filter on each side with Cf1 (1uF) and Cf2.  Are they
>just for smoothing DC?  If so, just make CLC pi filters on both sides.  Put
>Cf3 and Cf4 (like above) below the inductors on both sides.  This would
>allow much, much smaller inductors.  You could use 600 VAC motor run caps
>for the Cf caps.  You could use much higher cap values than 1 uF.  Run a
>spice model to choose size of capacitors and inductors for CLC pi filters. 
>Price should be very inexpensive.  

The values of Cf are chosen to provide a nice low side "spike" to trigger
the IGBT's.  They also absorb high voltage kickbacks off the inductor.

>If you really want to make it easier
>make CRC pi filters and use very low R high Watt resistors to avoid loses. 
>This would eliminate the inductors all together.

I'll check into this.

Cheers,

	Terry


>
>Keeping it VERY simple,
>
>RWW
>
>
>