Power Transfer OUTSIDE the work coil:
  In this short video, I am addressing a viewer's specific question about power transfer OUTSIDE of the work coil.
His question was rather general in nature, so I simply ran a couple of tests.  I could do a lot more testing if I had more information about his exact use:

/>

Look up "Steam Tables" to see what partial pressure it takes to evaporate water, at various temperatures.
  We used to take certain potted assemblies weighing about 2 pounds down to about 25 microns (pressure)  for at least an hour or two.  Those circuits ran at 20,750 VDC,  24/7/365.
We had lots of mechanical (vacuum) roughing pumps around that backed up oil vapor diffusion pumps.  They all "blanked off" at that 25 micron point.

Here's one simple reference that I found:

"around 0.03atm
Water evaporates when the vapor pressure is greater than partial pressure of water in the atmosphere. At room temperature, the vapor pressure of water is around 0.03atm. So 0.1atm is insufficient to cause boiling.  Aug 22, 2018"
---
Anyway, you need well over 29 inches Hg to do the job at room temperatures.  A simple 0-30 in Hg bourdon tube vacuum gauge isn't going to be accurate enough for you to see the difference anyway.

!! DO check out the steam tables to see if you can heat your stuff hot enough to get the water to "boil" at a pressure that you CAN obtain.

Pete Stanaitis
---------------

I do not understand this post.
Are you offering to pay someone USD$300 to design something for you?
You need to be much more specific about the goal of the project.

Re: "The piezo should be treated/replaced as a "leaky" capacitor...say creating sparks."
I don't know what this means.


Why do you need "80 volts at 9 amps?

Pete Stanaitis
----------------

Mosfet Gate Drive Concerns for ZVS Induction Heaters and other applications:
---------------------------
Mosfet gate driver concerns-
or-
Achilles heel for ZVS gate drive circuits
or
Running Mosfets with gate voltages too far below maximum

My Conclusion:
We must carefully design gate drive circuits to consider linear mode operation, even when running in "switched mode"!

Discussion:
Over the past several years, I have been experimenting with small ZVS induction heaters (1000 watts to 2500 watt models).  Early on, I had more than my share of circuit failures mostly due to overheating of the Mosfets.  ( I do NOT have these problems any more)
More recently, I have been using/attempting to use DC to DC SSR's to switch power to induction heaters.   It appears to me that all too many of these devices have poorly designed gate drive circuits.  I have even made a couple bad choices myself when attempting to repair a couple of them.
Much of this is documented on my relevant webpages and in my youtube videos.
  In addition to the above, I see, from time to time, other folks building  switching mode Mosfet circuits without, in my opinion, proper attention the detail regarding the gate drive voltage profiles, particularly when the Mosfets are momentarily running in linear mode.
Sometimes, I even have trouble understanding the gate drive voltage specs for a particular Mosfet from its datasheet.

Recommendation:
So--- I offer this link as a useful tool in understanding the care that must be taken in gate drive design and implementation: 

See:
https://www.infineon.com/dgdl/Infineon-ApplicationNote_Linear_Mode_Operation_Safe_Operation_Diagram_MOSFETs-AN-v01_00-EN.pdf?fileId=db3a30433e30e4bf013e3646e9381200

Pages 4, 5 and 6 are the most relevant
.

I know there are 3rd party programs out there that assist you in capturing data from the Arduino to put into a spreadsheet for analysis,  And I know that you can add an SD card reader to your project.  But I wanted an easy way to get my data into a spreadsheet without the hassle of downloading  some 3rd party program that might or might not come with some spam or spyware.  I didn't want to go to the trouble or expense of adding in the SD card reader for what might be a one time need to look at the data in graphical format, etc..
  So here is my solution:
/>
Pete Stanaitis
---------------

Asynchronous?

Here' a "follow-on video to the one I published yesterday.
I am simply catching up and cleaning up after all the time I spent making my SSR protection device work correctly.
In this one I tackle 3 subjects:
- A block diagram of my heavily expanded 2500 ZVS heater "system", with pictures to match the diagram,
-A simple spreadsheet that details current draw for a number of non ferrous materials.
-and, a little bit about repairing one of my recently failed DC to DC SSR:
/>
You guys should feel lucky that I won't bother you with ANY of several videos that I made DURING the process; those that were so boring and mistake-ridden that I'd be embarrassed if the ever saw the light of day.

Pete Stanaitis
---------------

Would it be worthwhile to extract the power supply (s) for bench use?

Hello Mads and TMax.
  I, a novice at this, have been working on a  "DC to DC SSR Protector" myself,using an Arduino and a rail to rail opamp to amplify the voltage from a 75mv current shunt that I already use to drive an analog 50 amp current meter.
  MY isssue is that, with the ZVS Induction heaters, if I inadvertently push a workpiece too far into the work coil, I can easily create a momnetary excessive current spike.  I need a way to shut DC power OFF before the SSR fails.
(By the way, the IRFP260N's in the ZVS heaters hold up really well at 40 + amps continuous)

  It appears that the project that you guys are discussing relates to problems shutting OFF an IGBT (or Mosfet, I assume) in an AC  (resonant?) circuit.
 
Question 1:
If that is true, then, does this desaturation detector have to operate in one cycle?
Putting it another way, does the IGBT fail in only one overcurrent trailing edge event, or is the problem with eventual overheating of the die?

Question 2:
Why are aren't you concerned just as much about the leading edge?

I ask because, in my situation, I am using a DC to DC SSR to control power to my 2500 watt ZVS Induction heater.  All I want to do is to shut off power ASAP if I detect current flow in excess of what I set in software.

So far I have built and programmed the sensing device and bench tested it using a simulated voltage input.  I have options as to how much code I can really need, since I am sending info to an I2C LCD  (and to the serial monitor), which might even take  many milliseconds.
Once I do get things going, I won't really need the LCD or serial monitor code, but It's nice to see exactly what is going on.

Pete Stanaitis

Description:My website and my youtube channel have dozens of broad "maker" categories and video playlists.  You need to pick and choose from the topic list on my main webpage and go to the playlists on my youtube channel to locate your own interests.

Website:   www.spaco.org

Youtube: https://www.youtube.com/user/frenchcreekvalley