Help ! 2 IGBTs High Voltage driving

Hi everyone,
Thank for your time,

I'm a french young engineer, and I'm stuck on a problem.
I'm trying to understand a PCB my company is using for Ozone generation - IE High Voltage board -

Here is a diagram I've made from this PCB

IC is a SG3525AN
both IGBTs are FGA25120ANTD

View attachment HV.pdf

The HV transformer is the TX2

So, as far as I understand, the IC is driving both IGBTs through outA and outB that induce current into the tranformer which applies current to the gate and "ON" both IGBTs.
There are 3 small variable resistors on the board, one drives IC frequency, one drives feedback loop (top right)(?), and last one duty cycle (?)
The last variable resistor (top left) is the potentiometer the customer can use to adjust the amount of ozone

I'd like to understand what's the second IGBT used for ? The one on the right. Because as TX2 is directly powered by the first IGBT, if this one is "ON" the second one should be useless ?
And what is the influence of the POT3 ? Does it drives IC duty cycle ?

If someone can explain to me, it'd be awesome !
Thanks;
Martin

Your Circuit seems Overly Complex.

Why don't you get some Ozone generating Tubes and ballasts?

Hi Chemelec, thanks for the answer

I don't know .. !

I'm just trying to understand the product they have. But in an other time, if there is a simpler solution it may interrest them.

The series circuit of two IGBT switches is apparently used because the transformer flyback voltage exceeds the voltage rating of a single device.

This looks to me like an arbitrary circuit compilation made without systematic understanding of power electronics design.

In any case it's impossible to analyze circuit details without knowing all component parameters.

- - - Updated - - -

I just realized that I have read your schematic wrong due to the unusual arrangement of components. The two IGBTs are forming a regular half bridge, feeding a square wave to the transformer. The capacitor may be tuned with the transformer leakage inductance for series resonance. I withdraw "arbitrary compilation".

Thank you very much FvM !

I've been looking around on the internet for a long time without result.
But now with the correct "half bridge" naming, It seems I'll be able to find exactly what I want !

I'll have a closer look on all of this on Monday, and see if I'm able to answer all my questions now.

Thanks again !