RE: IR - Half-Bridge Driver, Model & Schematic

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

Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



Actually, I was looking at your circuit.
One of the things I have been experimenting with is instead of increasing
the input voltage to
the full-bridge circuit (or half-bridge), you can add a step-up transformer
at the output
of the full-bridge instead.  I have been experimenting with a possible 5:1
step-up transformer with
very successful results.  With a maximum output of a 120VAC half-rectified
full bridge circuit of 340 V peak-peak
(at maximum 60Hz peak), the output would be about 1500 V peak-peak.

At first I was designing my full-bridge circuit to accomodate 480VAC input
but with very poor reliability.  However,
using a 120VAC input and a 5:1 output transformer, I am getting similar
results to the 480VAC.  Of course,
the tightly coupled primary/secondary must be EXTREMELY WELL isolated.  I
currently use PVC pipe and another HDMW polyethlyene sheet for added
isolation.

My goal as of now is too get a very reliable system capable of continuously
putting out 3 foot + streamers.  I am getting
very close.  I'd like to work up to maybe a 2 or 3kV p-p output.

For others who are interested, I am using ferrite U-cores to build my
transformers with.  They are available at
ferroxcube-dot-com

Dan







Hi Terry, All

Terry has graciously planted (THANKS!) preliminary IR2153D half bridge
sstc model and schematic at::

http://hot-streamer-dot-com  ir2153d-sstc-half-bridge.xls

http://hot-streamer-dot-com/temp/ir2153d-sstc-half-bridge.xls

CAVEATS:
1.  Circuit is unproven, USE AT OWN RISK.  Suggest powering at low
       voltage (24-30V) to determine functionality before applying line level
       voltages.
2.  All adjustments in this (or any derivation) circuits are FLOATING and
       AT LINE POTENTIAL.  Insulated and isolated potentiometers or
       knob hardware for frequency adjustment (or OV/OC setpoint adjustment
       in future enhanced circuits) are critical for operator safety.
3.  Vcc chip generated 16.5V is current limited by HV dropping resistor.
Any
       additional support circuits (Staccato Modulators, OV/OC protection)
       should use CMOS based active circuits and components, to limit current
       drawn from zener regulator in driver.

Additional information:

Jan Wagner>>
According to general specs on chip, source current is 200mA and
sink current is 400mA.  Based on IGBT shown (~100nC Qsw), this
chip should support charging GE junction in ~50ns, similar delays
with large chip FET's.  Both devices are rated at ~40A (600V IGBT,
500V FET)

IR also makes a enhanced version of this chip IR21531D that has half
the dead time (~0.6us).  This would allow operation to 200Khz + and
would be more suited for FET's IMO.

Chips, FET's and IGBT samples are on order, next step is to get some
heatsink / muffin fan hardware.  Will layout PCB  based on German
educational PCB.  1250W at 120VAC (voltage doubled +/-170V rails)
will require line currents of ~ 23A, and Lp = 23.34uH, Ct = 110nF for
Fo of 100kHz.

Will provide more information when it becomes available...
Best Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA


"Terrell W. Fritz" wrote:

  > HI Dave,
  >
  > Looks great!  I posted the file at:
  >
  > http://hot-streamer-dot-com/temp/
  >
  > BTW - The file opens fine with Sun's StarOffice spreadsheet program too!
  >
  > Cheers,
  >
  >         Terry
  >
  > At 12:06 AM 12/1/2002 -0500, you wrote:
  > >Terry
  > >
  > >Attached is a VERY preliminary circuit for a SSTC using the
  > >IR2153D self-oscillating half bridge driver.  Please place on
  > >hotstreamer, and I'll let folks now where it is.  Also in sheet
  > >is a model from Fairchild for an induction heating driver (which
  > >is also the primary front end of a SSTC; isn't that convenient :^) ).
  > >
  > >Current is dependent on tank Zo (as one would expect).  You
  > >aare much better off to run as high a voltage as practical on input
  > >to keep switching currents and losses down.  At least I'll use
  > >this circuit to get started, I have the 1200uF -at- 450VDC
  > >electrolytics.  A reader from the list noted to me that this chip
  > >is also used for high power push-pull flyback drivers using
  > >FET's for really large plasma globes, and include over voltage
  > >and overcurrent protection.  He is sending me a copy of a
  > >commercial 24" plsama globe using this technology so I can
  > >see if clues pop out about integrating this protection into a
  > >SSTC using IGBT's.
  > >
  > >This guy also looks like a really nice low cost modular driver for
  > >my IDR system as well, one PCB, two heatsinks and a muffin
  > >fan and you're ready to go.  Will stay in touch on this one...
  > >
  > >Best Regards
  > >Dave Sharpe, TCBOR
  > >Chesterfield, VA. USA
  > >