No Corona Discharge with ZVS Driver

[MaybeJosh]

So, this is my first Port here in this Forum.
Now to my Problem, I wanted to experiment a little with high voltage. I wanted to build a high voltage source for my own electric wind design. I am using a DC flyback transformer and have built two driver designs.
One design works with a simple 555 ciruit and the other with a ZVS driver board.
For my electric wind experiment I need to accelerate air molecules. A good indicator, as I understand it, is the corona discharge.

Now I have noticed that I have a much larger corona discharge with the 555-Ciruit than with the ZVS-Ciruit and that at lower power input.
However, I don't want to use the 555-Ciruit because even if the cathode and anode are far away from each other, about the same amount of power is required as when they are close together.
I can also set the frequency of the 555 circuit. But I can't get to a frequency that you can't hear and that allows the transformer to work at the same time. So I can only operate the transformer with a loud annoying noise.

So I want to use my ZVS driver, but I can hardly detect any corona discharge with it, whereas the arcs are much brighter and larger than with the 555 timer circuit.
Why is this, could someone help me out with this problem?

I have used different capacities with the ZVS-Driver because I thought it could be due to the frequency.
Unfortunately, nothing has changed with my problem. But I only tried: 0.33uF, 0.68uF & 1.36uF.

Values for the Circuits:
555: 7V 2A 5.93kHz
ZVS: 18V 8A

I actually have a few more pictures of the circuit and the corona discharge, but when uploading und attaching pictures I always get "Invalid Attachment".

[davekni]

I actually have a few more pictures of the circuit and the corona discharge, but when uploading und attaching pictures I always get "Invalid Attachment".

I've occasionally experienced the same issue.  However, ignore the message and attach anyway.  Image shows up at the end of message instead of where it was inserted, but still is there.  Images would be very helpful.  (I presume you are using an allowed image file type.  Mine are always ".jpg".)

I can also set the frequency of the 555 circuit. But I can't get to a frequency that you can't hear and that allows the transformer to work at the same time. So I can only operate the transformer with a loud annoying noise.

Most DC flyback transformers are designed for at least 15.625kHz (old analog PAL TV standard).  Likely to work OK to 20kHz with proper drive.

Are you using primary winding built into flyback transformer?  Or are you forming a new primary on other leg of flyback's ferrite core?  Added primary winding works best with ZVS drive.  For 555 drive (conventional flyback drive), internal primary works better.  Typically requires a high voltage FET for drive when using internal primary, and a resonant capacitor across primary roughly matching value used in original circuit.

[MaybeJosh]

Thanks for your answer. So far I have used an extra primary at the leg of the ferrite core. For the ZVS driver i used 5+5 turns and for the 555 10 turns. With 20kHz it works without too much noise.
I tried your suggestion with the internal coil. Now the 555 circuit is more efficient and produces stronger arcs with less power. The 555 driver also uses less power when idling.

Now i can create much more corona discharge, but is it possible to create the same result with the zvs driver?
It is still much more efficient.

I use the IRFP260N as the FET in both drivers.
What do you mean by a capacitor value which is used in which original circuit?
I got a ZVS driver with the Flyback, but it broke very quickly. It used 2x 0.33uF capacitors.

I have added the circuit diagram of my Flyback as an attachment. I used the coil between pin 1 and 2 as the internal coil for the 555 Circuit.

[MaybeJosh]

I have now connected a 0.68uF capacitor between the outputs of the 555 Driver. Now the arcs behave in the same way as with the ZVS driver.
It is now also much more efficient and quieter.
But now, as with the ZVS Driver, I no longer have any corona discharge.
Is there no driver or option how I can keep the efficiency and noise level but also generate enough corona discharge so that I can use the high voltage for the ionic wind?

PS: The heating of the mosfet with the 555 driver is higher than with the ZVS driver despite the capacitor. However, I expected this.

[davekni]

What do you mean by a capacitor value which is used in which original circuit?

HV flyback transformers were mostly built for CRT displays (TV sets and computer monitors).  When used in CRT circuits, drive looked close to your 555 circuit, but with a capacitor across primary winding terminals.  Unfortunately I have no way to know what value was actually used for any given flyback primary.  Probably less than 0.68uF, perhaps between 10nF and 100nF.  If you have an oscilloscope, proper value can be estimated by checking waveforms.
Without any capacitor, IRFP260N FET is going into avalanche breakdown on every on-to-off transition.  Wastes power and heats FET.

I have added the circuit diagram of my Flyback as an attachment.

I presume IRFP260N source connects to ground rather than +7V as shown in your 555 schematic.

I used the coil between pin 1 and 2 as the internal coil for the 555 Circuit.

Do you have a specification for this flyback transformer?  There's no way to tell from the schematic which pins were intended for primary drive.  Primary winding likely has low resistance (larger wire diameter) than most other windings.
Have you tried swapping pins 1 and 2?  For flyback drive into rectified secondary, output voltage will be much higher with one polarity than the other.
Most CRT flyback primaries are designed to be driven by higher voltage FETs, usually 900V to 1500V FETs.  Other primary windings may work well with lower voltage FETs, but also may have higher DC resistance and over-heat with continuous operation.

Now i can create much more corona discharge, but is it possible to create the same result with the zvs driver?
It is still much more efficient.

By "efficient" do you mean it draws less current?  That would be expected for a circuit generating less output power.

Because ZVS waveforms are symmetric AC sine waves, flyback output can't reach quite the same voltage as with proper flyback drive (555 style drive) into correct primary coil with correct FET voltage capability and parallel capacitor.  However, ZVS can likely achieve enough for your interests.  Difficult to debug without a scope.  I'd suggest first selecting ZVS cap value to hit desired frequency, say 20kHz.  Then increase voltage to ZVS circuit until output reaches what you want.