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Hi Sven,
For a semiconductor like a MOSFET there are several parameters that shouldn't be exceeded if its life is lo last for a long time. For longevity the temperature should be kept low. Heat is generated when current passes resistance. Thus have the MOSFET full conducting (saturated) or not conducting at all. Of course this isn't possible each time it is turned on or off as the voltage has to pass through the linear region where there is much resistance to generate heat. This should be done fast which gives other problems like inductive kickbacks. The inductive kickback can be absorbed in a snubber to avoid heating the MOSFET. Also do not exceed the MOSFET's breakdown voltage even though modern MOSFET's are avalanche rated. An electron avalanche through the crystal of a semiconductor still generates heat. Think of a spark discharge going through the crystal. Instead catch the energy in a snubber circuit to diverge the energy away from the MOSFET. Perhaps use an external spark gap in parallel with the MOSFETs to prevent the internal spark discharges. Another way of doing it is to detect when the drain voltage approaches the breakdown voltage of the MOSFET and then apply a signal to the gate to make the MOSFET conducting. This can be done with Zener diodes. But this still causes switching loss which heats the MOSFET. An external snubber takes the energy to outside the MOSFET.
A current of 4A through a MOSFET having 200V across it will dissipate 800W of heat power in the MOSFET. If the MOSFET is full conducting like 0.2 Ohm drain-source resistance the current of 4A will dissipate 3.2W. Each time the MOSFET is switched through the linear region a lot of power may be dissipated. Thus do the switching transitions fast and protect with a snubber. Fast transitions require a fast gate driver capable of charging and discharging the gate fast. I.e. it must deliver high current.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hi Ole, I have a push pull control built for the transverter. The problem are disorders the occur when the MOSFETs turn to the higher the voltage to so worse. I am so that started potentiometer and heat sink on mass to lay with slight improvement. After I the individual performance lines with aluminum foil wrapped have and this on grounded have are the disturbances way. But the MOSFETs are now is called for itself burden on a very large passive heat sink in itself performance. Sot227 MOSFETs 37 amps 1000v run I Max. With 4 ampere the thought I 10%. A suitable energy recovery snubber do I have yet to build. Next step all boards in a metal case with potentiometer incorporate. Greetings Sven
Von meinem Samsung Gerät gesendet.
-------- Ursprüngliche Nachricht --------
Von: "onielsen@... [EVGRAY]" <[email protected]>
Datum: 17.11.18 02:47 (GMT+01:00)
An: [email protected]
Betreff: [EVGRAY] Re: Neutral spike
H Sven,
"I have now wrapped all power lines with aluminum foil and this one-sided grounded."
Just be careful how the grounds are connected. Here are some EMC tutorial articles: http://learnemc.com/emc-tutorials http://learnemc.com/emc-tutorials
The current paths may still induce currents into other circuit parts when the current carrying wires form loops having enough area (i.e. one turn coils). Shielding that way doesn't help for magnetic fields. The signal wires would probably improve if screened cable was used. But it all depends on how the wires are rigged up to avoid loops transmitting and receiving magnetic fields (magnetic coupling).
"...the high-power mosfets are very hot although they are used at most 10%. The cut-off voltage at the drain increases in the kilovolt range when the transverter is connected"
What do you mean by 'used at most 10%?' When getting hot they may need more cooling or they are used at their maximum power dissipation. Remember the power dissipation given in the datasheet is normally when the surface of the device is held at 20 degree Celsius which is only possible when using water cooling or heavy forced air cooling like pressurized air flow. If the drain-source voltage is reaching the avalanche breakdown voltage of the MOSFETs this will dissipate a lot of heat in them. Also switching high voltages at high current gives great switching loss if the switching transitions take too long. During switching transitions the MOSFETs are working in the linear region which means both voltage across and current through them at the same time. This dissipates heat as voltage times current gives power [V x A = W]. Multiply this by the transition time to get energy dissipation [W x s = J]. Look at the gate source signal as this controls the drain source channel.
Have you found out how to make free energy or is it still just reactive power?
I have made some simple experiments along the way of Pierre Cotnoir's device. I may have simplified it too much as I used a bunch of small transformers instead of a motor stator as in Pierre's device. No excess power output was observed. My next experiment is along the way of the Clemente Figuera patents (http://alpoma.net/tecob/?page_id=8258 http://alpoma.net/tecob/?page_id=8258). He may actually mix the fields the right way for coherence to occur. This could also be the way Alfred Hubbard's device worked.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hello to all those interested, I have now built a push-pull inverter for the transverter anti-drive to drive it. From 37 Hz 650Hz is fully adjustable and the pulse width.
A simple square wave signal is generated and sent. It works wonderfully. The interference is a problem when switching 350V peaks. I have now wrapped all power lines with aluminum foil and this one-sided grounded. The boards I will install in an aluminum housing and also this ground, the disturbances are almost all gone. By shielding, the energy is no longer emitted and remains in the lines apparently, since the shielding, the high-power mosfets are very hot although they are used at most 10%. The cut-off voltage at the drain increases in the kilovolt range when the transverter is connected. The complete line to Transverter is also shielded. I now wanted to build an Energy Recovery Snubber to recycle that energy. First test show that you can drive the transverter so much more efficient. I have to build this inverter even more reliable or change.
Best regards
Sven