Re: Aw: Re: [EVGRAY] Re: Sven's transverter

Body

Hi Sven,

Depending on how much the core saturates its inductance decreases. At full saturation any change in the magnetic field is seen like the coil has no core anymore. This is because saturation means no more atoms or electrons to align with the magnetic field. The coil then behaves as if it has an air core meaning way less inductance than when having an unsaturated iron core.

Resonance happens at the frequency where the inductive impedance equals the capacitive impedance as one is positive while the other is negative. Thus they cancel out leaving only the parasitic resistance of the wire and metallic parts of the components. At ferroresonance all kinds of jumps in inductance happens depending on the degree of saturation. This makes all kind of values of resonant frequencies happen. A ferroresonant transformer has an extra leg to where the magnetic field jumps to somehow keep a higher fixed inductance than if the core just vanishes (by saturation) as seen from a magnetic conductivity perspective. Only a tiny part of the core is actually being saturated as saturation makes great loss by heating the saturating parts.

For little energy to resonate the core keep the losses low like only saturating a small piece of the core as being done in ferroresonant transformers. If high voltage and low current is wanted the impedance of the winding has to be increased by increasing its number of turns. Doubling the number of turns mean quadrupling the inductance. For the same resonant frequency the capacitor then has to be only one fourth of its former value. The voltage is then doubled and the current is halved. The total current [A x number of turns] going around the leg stays the same.

The jumps in frequency and peak current happen because the core becomes saturated to different degrees.

Regards
Ole
 

---In [email protected], <s.friedrich@...> wrote :

 Hi Mick,
 
 yes, I tried to make the core squeak like a pig. laughing. It is not that easy to measure, according to the shunt there are current peaks over 100 amps measured with the scope. I try to find the sweetspot where I need very little energy to resonate the core.
 The question is where do I have to look for and how should that look. My original FR transformer has a very high voltage and the current is not so high and the current flow is not so sharp. Ferroresonance and saturation is somehow similar. The higher the capacity, the stronger the saturation and the lower the frequency where it occurs. Where do I have to search, maybe Hector has an idea!?!
 regards
 Sven

  

     Gesendet: Freitag, 25. Januar 2019 um 14:37 Uhr
 Von: "Mick mkjekyll@... [EVGRAY]" <[email protected]>
 An: [email protected]
 Betreff: Re: [EVGRAY] Re: Sven's transverter
    
 Sven,
 You have gone over to top on this project, looks like Frankensteins lab:-) Great work!    What kind of energy have you measured in watts per second?
 The core sounds like you are torturing it on a rack.
  
 On 1/25/2019 7:40 AM, s.friedrich@... mailto:s.friedrich@... [EVGRAY] wrote:
   Hello Warren and All,
 
 I completed my push-pull control and performed initial tests. The mosfets stay cool and the recovery diodes too. I have an energy-recovery circuit built in with an additional inductance of the large transformer behind it, which I abused for it. But I have not experimented with it yet.
 I also did a video.
 I noticed that the bigger the capacity, the bigger the saturation or the sharper the current flow. At high voltages and smaller capacities and higher frequency, the current is not so sharp.
 
 What is important to achieve the best operation. The noise with a higher frequency is infernal, sometimes it creates a kind of stuttering in the core. Listen for yourself.
  
 https://www.youtube.com/watch?v=YH6KJjBrecw https://www.youtube.com/watch?v=YH6KJjBrecw
  
 regards
 
 Sven