David

time to introduce the generic 'vga' gdt  with its standardized dimensions, im pretty sure the specs wont have large differences from other manufacturers.

im sure the op could find a few

David

regarding OCD, I have my 3rd CT(isolated) with 100Amp/per volt.

What do I have to modify so the existing LM311 have the same output?

I would be using my existing 1:32:31(currently ocd) to be the new fb_ct input.

thanks

David

as per your reply, here are some images and scopeshots.
blue=primary current , 1v=100amp
yellow=Full-bridge output, scope x1 , probe x10 with 2pF in series
note=I made a new GDT here. taken from VGA cables, making sure they both look the same. they have the same dimensions as per your posts. 3T and measures 40uH.

judging from my previous Iprim scopeshot, I think these now have better(?) results... same setup, only GDT changed. there are still those noise but are far lesser

**I have opto on the interrupt input (RCA)
***I have direct connections (GND) from arduino (pwm-ramp) to buck, but controller and buck are separately powered though they share the same GND. I wonder if I should opto-isolate this as well(?)
reason Im using opto is that fiber optic parts are hard to come by.

**point0000.png the initial ramping on the bridge output is 450KHz. and when Iprim starts ramping up, its 370KHz. and because of the 'fast rise' of bridge output, spark output branches early on! 

this -stuffs/early branching of arcs- just happened when I increased UD mosfet drivers supply from previous 20v supply(smps) to 24v Linear-regulated. and from the buck gate driver 15v(smps) to  25v Linear-UNregulated.

-or

just my controller settings!
edit: redid test, adjusted the 'wick' control, even to the minimum setting(virtually removing wick voltage) but there is still the 'quick rampup' on bridge output..

edit2 on phone photo. I have adjusted scope brightness to minimum. no its not 'quick rising'.

David

before, Ive had smps power for UD and buck control circuitry(Gao), power input from LiPo battery.

I have tried using Linear PS for the UD. IGBT driver ps is from 7824 regulator.

on the ramp buck side, Ive got the IGBT high-side driver in un-regulated 25vdc(17Vac traffo).

can you please check attached. where are those hashes/spikes coming from? previously, same problem with using smps power for UD and buck control.

edit: I was thinking maybe I would get 'cleaner' system with Linear PS for the logics and drivers.


the only smps power left, is the boost (16v8 to 300Vdc for buck power)

Those look fine.  A slight reversal at the end of the main transition is not problematic.

Thats great!

Indicates you have sufficient dead-time and barely enough phase-lead.

with "barely enough", does this mean I need a slight component adjustment on the lowpass filter? ~1uH perhaps since my coil works better at lower frequency (370KHz). and perhaps why this is so, because of said IGBT being THAT slow? based on datasheet for 40T60, its calculated speed is said to be ~270KHz. when changing primary MMC from 13nF(Fres=370KHz) to 8.2nF(Fres=430KHz), the triple transitions have higher swing and Iprim more noise. so I take it as a hint that it could either be lacking on the lowpass filter, or slow IGBT (or maybe im wrong?)

Looks great!  Nice progress.

Thanks. goal is 1Meter for this battery-powered

All scope probes have reduced maximum voltage capability as frequency increases.  Some (especially cheap probes) drop dramatically at TC frequencies.

good info! seem to have forgotten about the freq response. but is ~400KHz too much for a 100MHz rated probe?

For many purposes you can get away with a small capacitor (of sufficient voltage rating) in series with the probe tip, value ~1pF.  I often home-make such capacitors with just two twisted insulated wires

I would go this route. gimmick capacitor. but probe switch set to x1 only? how do I set this up on scope?  and could I get an accurate voltage reading (for TC use) of these?

to be more complete, I redid the scoping on 'peak' acquisition and did some more zooming
------
and as compared to a 'high-res' mode

Hi David

kindly check my scope shots. should I be worried about those negative going spikes? and why only on the negative side? and also, they only show when I change to shorter scope timebase. scope error?

Im now using 8pc IGBTs. BT40T60.  is it still ok to use 2R2 gate res for each IGBT? or should I raise it something like 5R since they are now connected as parallel.

the (kit)power supply I am using:
https://www.qsl.net/z33t/dc_0-30v_0-3A_eng.html

so I just set the 'current' pot to minimum, and checked if there is output voltage.yes there is.

ok my igbts are counterfiet, except the IRG im using in the buck switch.

my lcr meter shows. 0.00 reading with open leads. ill try using ferrites for the coax then. thanks

current regulated. its my CV CC power supply. I set it to 2mA only.

I have re-checked both igbts 60T65PES and 40T60 with 100nF(94nF actual) and 10meg

too bad they are fake too. glad that it was refunded

thats why I dont overdrive much my 60T65PES 

anyways I ordered(yet another) 10pcs because they where sooo cheap.
used my yellow LCR meter to check my un-used 60T65PES(for comparison) with these cheaper igbt. checked datasheet and gate capacitance seems close to the LCR reading. its only 80A@25degC so I will 'double switch' this for a full bridge and drive this to 150Apk. ran out of igbt heatpads, ordered them. will arrive 2 weeks tops.

will see if it holds up!

just curious, how did you test it to ~30A only? id imagine you also 'heat up' the igbt prior to testing