Hi!

A little time passed but I found problem why I cannot did phase lead properly.
In low power arrangement where current transformer has one section there is necessary to add in serial to CT resistor. Without it phase lead is impossible. I did just like below:



Resistor has to be about 1K and 5W or  little more to keep safe level from overheat. I used 100uH choke as coil and 200R variable resistor. I got zero cross but strange thing happened.
First half wave seems to be fine, but in every next cycle phase lead get disappear and time delay is getting greater. I suppose that is caused by choke which I used and it’s not intended to this type operation. I added 1uF capacitor which makes work of AD790 more stable. At first cycle it likes to oscillate regardless from voltage offset at second input...
 
To set ZCS I just using variable resistor. Coil has 100uH and looks exactly like this:



I suppose I need something like this:



About FET’s. I used them but system will be feeded up to 24V just like ZVS induction heaters. It’s just did for educational purposes only and in further I want to use IGBT’s.

5V zener clamping diodes works fine just like signal diodes. I had never lost any AD790 at this moment:) Only keep in mind to not overcurrent them...

Scope screens:





At this moment I need to find why I got this strange delay...
I suppose wrong type of burden coil...

Hi!
Did You check these simulations in reality?
Does results are quite similar like results of simulations?

I don't see anything wrong. Current leads voltage, because You have not phase lead. ZCS lag is mostly similar and depends from electronic components used in construction. You need to do phase lead. If Fres will lower then angle of lag will be lower also. (time of delay electronic components is same). If Fres will be higher then angle of lag will higher too.
Have You tried to do phase lead?

Hi!
Yellow trace is current measured from same CT used for feedback.
Blue trace is voltage measured on fullbridge inverter.
Current transformer has 60 windings on TX32/19-3E25 Ferroxcube core (white painted with orange one side).
Summarizing:
1. Zener diodes 0.5W gives poor protection and are harmful in any way for (distort/delay) signal?
2. Current transformer may not give to much current and voltage, because power stage is feeded from 12V supply until I make proper phase adjustment.
3. AD790 configuration seems to be fine and I based on predikter driver. Should I something to change?
4. In R24 case higher resistance gives more delay of phase lead?
5. It is good to use instead R24, R1 and Burden Coil use RF choke with high L and R just like this kind of chokes:
https://www.bourns.com/data/global/pdfs/70f_series.pdf
6.  I'm just only struggling in innsufficient phase lead. Some people in Russia founded for it special calculator, but I don't know russian and cannot understand how to use it:
https://tqfp.org/calculatoria/sd_predictor/?f=80&t_predict=300&r_predict=50&r_delay=1k
 

Hi Everyone!

From some long time I’m going to make DRSSTC power supply for Tesla coil, which resonant frequency will have about 180-220khz. I want make fullbridge at IGBT’s in TO247 packages. At this stage I shouldn’t have problems, because I did some coils and SSTC drivers.
Back to the topic of DRSSTC I had read all present in Internet website articles about DRSSTC drivers also in order to not ask too obvious, trivial and clear questions which may to litter forum topics.
One thing which for me is not too clear from component side is proper arrangement CT and phase lead section. I did working prototype driver based on Steve Ward Driver schematic with phase lead below:



I decided to make this driver, because it seems to be easy for me.
Driver is working with power section feeded from 12V supply to begin from safe level but I cannot reach phase lead. I have 400ns delay with time of switching in relation to tank current. Regardless that my frequency of tank has 50khz or 100khz switching delay is same and is about 400-500 nS. It is normal behavior resulted from natural time delays of logic and power sections?
When in this circuit I want to apply phase lead in same way like in schematic I got huge voltage drop which causes that my driver cannot work properly at all. If I put much larger values of burden L and/or R then I cannot reach phase lead and 1K (5W) resistor near clamp diodes gets very hot.
For me is not critical to stay with Schmitt trigger as feedback buffer. It may be any other fast comparator like LM311P, AD790, AD8561, LM306P, MAX941/2 etc. (I prefer THT package). I tried this solution, because it seems to me most safe for logic and is very silmilar like in SSTC which I done...
In conclusion I need to do proper feedback section step by step. If I want at this moment make fullbridge on TO247 IGBT about 200khz resonant frequency coil  what should be done with:
1.   What is the best core for current transformer? (core material, Al, dimensions, manufacturer).
2.   How many turns should have current transformer? (For low/medium power DRSSTC)
3.   It is necessary to schmitt/comparator input give current limiting resistor (like 1K) in series?
4.   Maybe trivial question but clamp diodes for protecting input also?
5.   What values should have burden resistor and coil how important is mutual relationship beetwen burden resistance and inductance?
6.   What type of burden coil is the best: aerial or with core? It seems to me more suitable to make phase lead only by this without making any delaying section with pots. (like in predikter driver).
7.   Does  comparator LM311P is good for low/medium power of DRSSTC?
8.    It is good idea to make feedback and OCD from one core? (One core is wounded UTP bifilar wire?)
9.   Any tips what is important and need to be take account in input/current feedback section will be very thankfull.
10. Any good examples of input arrangement for input schmitt/comparator...

Best Wishes!