coil capacitor using voltage and current impulses

evostars

Re: coil capacitor using voltage and current impulses
« Reply #600,  »
so this is the current on the HC coil. it is larger, but has the same phase as the HV coil.
hmmm confusing. would it be the same current (displacement current, which I before also measured in mid air?)

 SCR17.PNG - 40.46 kB, 1280x824, viewed 3 times.


evostars

Re: coil capacitor using voltage and current impulses
« Reply #601,  »Last edited
its nice to finally get some grip on the circuit, and to be able to predict how it behaves.
The slow turn on of the mosfet, might be due to the low capacity providing power to the gate driver.
It demands a current spike to charge the gate fast. and if the isnt enough charged capacity it wont fire decently.
this might  also results in the power fluctuations (ringing), which translates to the tl494 output distortions.

also the large capacitors C25 C26 C24 have become obsolete, since I dont use a choke for DC offset.
I only use neutral, so now VCC4 is floating. I can short that out to neutral.

in my new design I enlarged those gat capacitors to 1uF, but now they are 1nF (c21 c22) so... I will need to put some 1uF caps parallel  to those ceramic 1nF's


evostars

Re: coil capacitor using voltage and current impulses
« Reply #603,  »
I tuned down to 57kc which gave higher voltage. but that means lower currents, so I might need to remove some of the push pull secondary windings.
I checked, and inductance is related to the square of the turns, indeed not linear
I placed a 3uF polypropylene cap parallel to c21 (1nF), so the gate driver will have more current for the C3M mosfet turn on.

evostars

Re: coil capacitor using voltage and current impulses
« Reply #604,  »
It now runs at 56.6kc/s
the noise on the gate is still there. probed between the second tl494 and the gate driver, at the resistor to neutral.

current and voltage are both maximum, so that is good.
then... I should start measuring output. first need to rectify. but can alresde should be able to probe ac current and voltage

evostars

Re: coil capacitor using voltage and current impulses
« Reply #605,  »Last edited
I increased power an saw no voltage or current on load, except for large noise signals at time of the discharge.
Also the PSU acted up weird again. Now the first channel which is completely disconnected showed voltage.

So a series diode with M should fix that.
or a battery. but Im not ready for that

I also wonder, I now use 2 floating psu's one for the PCB, and one for the push pull.
the M mosfet is grounded on the PCB. So it would be wise to series connect their neutrals

evostars

Re: coil capacitor using voltage and current impulses
« Reply #606,  »Last edited
hmm interesting
 I connected the 2 PSU neutrals and then the HV coil phase was flipped. (pusle on positive max)
I will solve this by reverse connecting the push pull primary

edit:
 that didn't change phase!
eh....
is that the same transistor problem again?

evostars

Re: coil capacitor using voltage and current impulses
« Reply #607,  »
When the M mosfet is not connected, there is still current flowing in the high current coil.

phase shifting only occurs when I am at the dead end of the delay pot (eiter end) so no problem, as I can set the phase where I want it to be.

I retuned the system to 61.9 kc (without M) where it give 1.6A pp current.

the power supply still acts up, so it needs a diode on the negative side. the PCB capacitors should then be able to handle the negative voltage of the push pull HC side.

Maximum voltage is lower when M is connected. current is also lower.

I can not phase shift the current (yet).

bottom line, the voltages are to low.
I don't know if the parallel resonance is already working as it should do. that 1.5A is that from the pp transformer?

many questions.

I should first see if there is a current difference over the HC coil. which is hard due to the probe position influencing the measurement.

but I can measure current on the wire from the secondary of the pp coil, so if that is equal, then it is clear the parallel resonance does not work (yet)

evostars

Re: coil capacitor using voltage and current impulses
« Reply #608,  »
ok there is parallel resonance going on, without the M mosfet.
Current is much larger on the outside of the HC then on the PP side.

pp does deliver current which is normal, but at a much lower level.

So if PP is grounded to neutral is shoulg give quarter wave higher voltage on the HV side.

So only not grounded to neutral during the positive rise of voltage on the HC coil.
 So bypass diode, to keep the body diode from getting warm.
And a diode to the PSU negative side.

I also moved the output coil ground to the other side (which is the parallel resonant side). I measured current on the grounded side of the load (8.2A) I dont know what to think of that, as I have no voltage reading there ... eh....
what?




if the pp gives output that is out of phase. then would it make sense to flip the coil connection over?
I could easily connect the other side of the HV coil to the PP and see what happens.


evostars

Re: coil capacitor using voltage and current impulses
« Reply #609,  »
main problem:
 voltage is to low.
more inductance on PP will also lower the Frequency of resonance,
which demands even larger capacity to tune the HC down.

its not working
 :'(

evostars

Re: coil capacitor using voltage and current impulses
« Reply #610,  »
ok lets ground the PP on one side to neutral, and isolate it from the current coil.

the current coil then needs a separate low voltage supply, which can be quickly discharged by M.

the quarter resonant sine wave was pretty perfect. a slow rise with a quick discharge to neutral.

Before I used a dc supply, and a choke to limit the current.

but the choke became resonant with the coil capacitor CC

actually that would mean the resonance was induced by the CC, and thus not tunable. as the PP would set it.

but that would actually be good.
then. lets get that choke back in, and see how that works again. No DC supply needed,
just M to discharge to neutral.

there is also still the dual choke trick with one half having a diode to ground for the negative cycle. that would make it counter wound for the negative half, so it would appear to have no inductance? hmm? no not true, or... worthy of testing

evostars

Re: coil capacitor using voltage and current impulses
« Reply #611,  »
earth ground on the LOAD should be placed on the open ended side of the high voltage coil(HVC)
discharge Mosfet M should be placed on the opposite end (pp side) of the HVC

The HC coil could work with only a DC supply, with common mode Choke in between it.
one of the CMC has diode to ground passing negative

evostars

Re: coil capacitor using voltage and current impulses
« Reply #612,  »
just did some test with new setup.

No choke no dc. still the HC coil produces current and becomes resonant.

HV coil also produces current.
I had 2.4kV pp
above that I had corona discharge around 3kV at 12v psu which messed everything up.

Since I reverse connected the HC coil and the earth geound on load, the HC voltage was now in phase with the HV coil.
meaning that also the current of the HV coil and HC are in phase. but not precisely.

there is a little lag in the current of the hV coil.

So. to discharge at the V max negative of the HV coil is now impossible, but it can be done, if an external voltage supply is used tongive the HC a positive dc offset for discharge.
again a choke is needed.

if that choke becomes resonant, then it would increase the positive voltage of the HC during the discharge.

Actually the parallel resonance is then at neg max. while the choke series resonance would be at positive max.

evostars

Re: coil capacitor using voltage and current impulses
« Reply #613,  »
how are the phase angels of the mosfet pulses and the voltages of the sine waves produced?
the HV coil voltage sine would be v+ max when the pulse goes high and the mosfet activates right? or is that at V-max?

then the pulse of the HC coil should be 90 degrees delayed. But that would mean to switch at the zero volt point of the HV coil.

I need to measure and get it straight in my head.

I fail to understand why I cant phase shift.
and see no cold current.
Is my load wrong? I am using a 8.2ohm 50w resistance. lets change that to a halogeen bulb their resistance is different when cold.

evostars

Re: coil capacitor using voltage and current impulses
« Reply #614,  »
a halogen bulb has low resistance when cold
and allows relative high current at low voltage.

when it heats up, resistance is increased.
it starts emiting radiation. which could be understood as a displacement current flowing out of the resistance.

as this longitudinal radiation displacement current increases when higher voltages are applied it limits the transverse conventional magnetic currents, and thus explains why the resistance goes up.

is that right?

so my 8.2 ohms might be to low for the load.
it needs to be higher

evostars

Re: coil capacitor using voltage and current impulses
« Reply #615,  »
a 60-watt halogen light bulb has a resistance of about 882 ohms when it is fully lit, but only about 65 ohms when it is cold1
. A 100-watt halogen light bulb has a resistance of about 529 ohms when it is fully lit, but only about 39 ohms when it is cold

this is from chat gtp4. it relates to a 100V bulb

so yes my load resistance is to low

evostars

Re: coil capacitor using voltage and current impulses
« Reply #616,  »
ok I was right. V max is at the start of the pulse of the push pull driver
so 90 degrees later or earlier the voltage is zero, and the current is max. and that is when I discharge M.
So I do need a voltage present to do this. f*ck that is weird

 start pulse.png - 84.85 kB, 1280x800, viewed 2 times.


evostars

HC coil inductance 2.4uH
« Reply #617,  »
HC coil inductance 2.4uH
just measured again, while being inside the nested coils system

evostars

Re: coil capacitor using voltage and current impulses
« Reply #618,  »
I have removed the load (new load not yet in place)

I inserted a choke of 1.4mH between a new dc PSU (16.6V) and the current coil, choke is connected on the HV coil open end side.

so DC voltage is supplied to the HC coil, through a choke. While it is discharged on the other end of the HC coil, by M mosfet.

funny to see, now the voltage of the HC coil shows no mirror of the HV coil, but instead
when the M is tuned to discharge at the 0V point, it gives a inductive spike (orange), after the mosfet is turned off.
All funny, but not what I wanted to see.
but good, that the coil is now not parallel resonnant (not sure).

First I need to see the voltage discharge on the current coil. is it happening? I probably need to adjust the choke

duty cycle need to be lowered. I dont want to charge the HC coil with current. I only want to discharge the DC voltage.

 choke.png - 92.52 kB, 1280x800, viewed once.


evostars

Re: coil capacitor using voltage and current impulses
« Reply #619,  »
I added the load, cold it is 82ohms it is the 3x halogen in series (230v 220W each)

orange shows the HC coil at the M mosfet. clearly the Choke rings again.
blue is the current of the HC coil on the other end. So it appears to be still resonant from the HV sine.
the HV current still has a small phase difference.

ornage has 20V/div the voltage applied (dc) is 16.6V) so there is barely any discharge.
If I tune the choke correctly, it would give max positive voltage, but is that wise?
The choke is resonant with the coil cap, so phase is again driven by the pp transformer.
if it is tuned down to 1/4f it would work. This is the path I was on before.

 loaded.png - 95.38 kB, 1280x800, viewed 3 times.



evostars

Re: coil capacitor using voltage and current impulses
« Reply #621,  »
I put the common mode dual winding choke in. both wingings have 2.4mH and I connected them in series (12mH)
one winding used as choke, other winding going to neutral by the negative passing diode.

I can now see the voltage drop, while I put 16.6V DC over it.

after it there is still a half wave ring. but that is not a problem.
The problem now is that when the mosfet turns off, there is a large spike, so I need a fast diode to kill that.
the M mosfet needs protection.

 spike.png - 82.71 kB, 1280x800, viewed 5 times.



evostars

Re: coil capacitor using voltage and current impulses
« Reply #623,  »
some more insight.

If there is low impedance, then current can flow.

this happens when a sudden voltage is presented to an empty capacitor.

When empty the cap has low reactance so low impedance.

so it is not about the coil capacitor. being charged or discharged when full.

the voltage change happens at the current maximum,
because a coil has kow reactance when it is charged. then impedance to current flow is low.

so
when the coil capacitor is empty. meaning zero (resonant) volts, the current is maximum.

so this is the lowest reactance/ impedance point, where max current flow is allowed.

So if at this zero volts point, a sudden voltage is present, then large currents flow into the coil capacitor.

thus. indeed the M mosfet changes the voltage rapidly at the max current / zero voltage point of the coil capacitor.

this is 90 degrees delayed. or 270.
the large inflow of cold current happens due to the low impedance point, and having a voltage difference on the capacitor plates.

the cap field needs to be suddenly filled.

so M switches the HC coil from positive to neutral voltage.

but this should represent an increase in voltage of the coil capacitor.

so indeed thr HV- and the HC coil need a common reference point, to create the energy vacuum at the voltage change.
which then create the inflow of energy which is the cold current. the displacement current
from the environment.

so basically everything is floating until the discharge, which actually is a charge.
then, the HV coil should be equal in voltage to the HC coil at the switch on of the M.
if 15V is used, HV should be at 15V.

the inflow happens at the max current point, low impedance, so the a Max current should increase when M switches HC to neutral.

evostars

dc offsets
« Reply #624,  »
So I switch M to neutral at the moment that reactance is lowest. when voltage is minimum and current is maximum of the coil cap.

What If I also gave the push pull secondary a dc offset, instead of straight to neutral?

with a large enough cap.
the push pull would act as choke for the current draw of the high dv/dt


then HC and HV coil both are zero at the same time, and have the same dc voltage offset.
whereby the HC coil suddenly changes voltage.
to induce the high displacement current, that amplifies the HV current, and its voltage!