Radiant power from Solid state Tesla hairpin circuit

[fejleszto]

See some of my simulations, it can be useful. But please correct me if I'm wrong...!

[evostars]

keep in mind simulations work on known principles(formulas), they for example wont show Longitudinal wave effects.

[fejleszto]

Hi Ivo,

I've began with the work, and I'm stocked by the testing of the circuit. The switchings are relative clean (tested with a resistor), but as you can see at the scope pictures, if I increase the frequency, the duty cycle of the square waves will be less, even of unequal manner in both side (high-low). My signal generator gives a good signal shape directly checked with the scope. I do not understand the phenomenal. Do you have any idea or did you see something similar?

My other question: the pancake coil gives me a pure resonance of about 600 kHz. It's a beautifull dampened oscillation, but we need rather only ONE fast, large impulse (the first part of the resonance) and not like this. How do you achieve this like in your 2019-12-14 video (see attached)?

Thank you!!!

[evostars]

fejleszto, very cool to see your version of the radiant half-bridge PCB working.

I have no Idea why the duty cycle changes. Suspect something to do with the ground of the square wave signal?

check If you bridged the source to the negative of the gate driver IC

The damped ringing of the L1 coil, suggests you have not connected the series resonant L2 coil (and its series capacitor) to the half bridge.

the series resonant L2 provides a low impedance path to ground for the energy of L1, during dead time.

So dont use 50% duty. use 49% or even less.

when L2 is perfect series resonant the impulse of L1 will not be visible, as it is fully absorbed into The series tuning cap of L2.

when tuned slightly above resonance, the impulses will appear (voltage probe between series cap and L2). these impulses are the voltage half waves of ringing L1 (energy is transferred into L2)

I don't know which isolated dc dc you have used, maybe that could also be a cause for the duty cycle problems

[fejleszto]

Hi Ivo,

thank you for the very fast answer!
I've found a solution for my problem: if I add +2,5Vdc offset to the 5V input signals (square waves) with the signal generator, anything works just fine at all frequencies!!! I don't understand exactly why. The negative inputs of the drivers are grounded. Perhaps the two sides should be better separated, I dont'n know...

I understand your answer in terms of damped ringings and so, I'll keep working.