Plasma Ignition

Originally posted by shmot   Collector is connected to battery ground and emitter is connected to 320 V ground.

Ah ha, now I got it.   That's why your drew the IGBT  this way.   You notice I drew it backwards.    

Originally posted by shmot Simple math: Power what heats air-fuel mixture is plasma threshold voltage x current. If coil output voltage is 50 kV, current 1 A and plasma threshold voltage is 50 V, the power what heats air-fuel mixture is 50 V x 1 A= 50 W.

Originally posted by shmot     At same time power what is needed to produce is 50 kV x 1 A = 50 kW. Only 0.1 %......

Ok, I think I sort of follow your logic on it.   So, I am back to my first question on how you measured the current.     

I understand that I=V/R and I understand your idea of having the R in the return leg.      The problem is it's not that simple.  First R is not R.  R is a complex device made up of capacitance, inductance and resistance.   If you took say a 1K 1206 resistor and used it at DC, sure it's about 1K.  But we both know that at this frequency, this will not be the case.  The inductance may be the dominate component.  You need an R that is very stable over a very wide range.   

Next will be the scope that was used.   We both know that 0.35 / fBW = Trise assuming we are not talking about a system using modern digital filters.    The current signal is very fast and will require a very fast scope to see what it really looks like.  

Interconnection will also play into this. 


So, let's start with how did you measure the current.  What scope, what sort of sense.  Any pictures, models numbers, etc. 

I find this thread to be very interesting.I cant help but to be reminded of a seminar I attended some yrs back where a Ford engineer was addressing fuel mileage,that led to air fuel ratio's and ignitions. We were told that in yrs to come 14.7-1 would not be the optimum ratio for fuel mileage with gasoline--it would be much leaner.The problem he said was lighting the leaner mixture.He said that it took a flame to light it-not just a spark as we had in a conventional gas engine---He mentioned a plasma ignition that Ford was playing with to light the leaner mixture

Originally posted by geek I am guessing that a 1MHz sample rate is not even close to what you would need to see it.  The scope you used could be very old and still work.  It would have been a very high end unit for the day.   Then the resistor would really have to act like a resistor.

Spark duration is around 50 us. 1 MHz scope should should give general view what is happening. For more detais here is one cheap way to build 100 MHz scope
http://www.fpga4fun.com/Hands-on_Flashy.html

Originally posted by geek Now that I understand what your doing, it would be interesting to duplicate your testing to compare results.   Do you have the MSD coils and wires?   If so, we could start with a very simple test to just to compare the method used to measure it.   Let me think about it.

Yes, we could compare results. I do have Nology 0.6 ohm coils and and Nology wires.
http://www.nology.com/profiremotor.html
http://www.nology.com/hot.html
It would be nice to have system where I could set wanted spark current and spark duration...


Edited by shmot - 17 October 2009 at 11:40am

I checked out the scope link.  That's a pretty fun little project.   Is this the one your wanting to buy?   If so, I wonder if we could make a little tweak to the design to give you your waveform generator rather than using a stepper motor.  

Both my ignition trigger simulators use FPGAs.  The complex one uses an Altera and I have a very simple one based on a small Xilinx part.  Nothing fancy but can do the basic waveforms for the Dyna and MSD (single and dual mags.).     I wonder if we could add this simple one to their design.   If you get it, and they provide all the source for it, let me know.

I did a search on the nology wires and one of the first links was this one:
http://iwcweb.com/eclipse/html/warning.html
Parts are pretty funny.   Reminds me of this site's blacklist.  

Do you have any scrap of this wire that you can section and show a picture? 

I would tend to believe what your saying Scott about comparing the various wires.    Right, they make the capacitor. 





The following link is for the entire patent if you care to read it: 

http://www.google.com/patents?id=4wINAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q=&f=false

I was able to find a lot of claims  but no real supporting data.     The following is a promo on youtube:

http://www.youtube.com/watch?v=r5RVbaQt5fM

I used to love watching those Slick 50 promos.  Watch us drain all the oil...... 

What is interesting is the claim of speed and power with no other changes.  Hum.... Maybe if you started out with bad parts?  

The basic problem I see is having this "inner capacitor member" and  "outer member"  break down.    It would be fun to try a set to see at what point they fail in my little chamber.   Guessing Dynatek may have this data.   Anything you are able to post, I would really like to read it.  May be the closest thing to an unbiased study out there!!

Having a capacitor right next to the plug will have an effect.    But if you can't measure it, it really does not matter. 

Originally posted by geek I checked out the scope link.  That's a pretty fun little project.   Is this the one your wanting to buy?   If so, I wonder if we could make a little tweak to the design to give you your waveform generator rather than using a stepper motor.

This USB2-based Saxo-Q should work as 150 Ms/s 4-channel scope and it has 2 D/A outputs.
http://www.knjn.com/FPGA-FX2.html
http://www.knjn.com/shop.html?pg=pic&src=images/Flashy4ch.gif&title=FlashyDemo&menu=0
It should also be used as signal generator
http://www.fpga4fun.com/DDS1.html
Nice toy for $250. Do you think that it would do what is needed?


Edited by shmot - 18 October 2009 at 10:58am

I came across this article on a home made target.  Similar to what we would normally use to calibrate a gun.   
http://www.conformity.com/artman/publish/printer_75.shtml">http://www.conformity.com/artman/publish/printer_75.shtml

Spent some time to cobble one up using 1206 inside hole rather than slot.  Cut the rings using a lathe.  Stuck it on the VNA.  Not good, but decent to about 1.4GHz.  I used a 4-wire meter to check the DC resistance.   I had some Midwest Microwave attenuators that I used to couple it to the scope.    Next took the starter from the gas grill.  Nothing like the MC4, but its a spark.   My scope can do a 1GS single shot with a BW of 500 MHz.     I have another with a 4GHz BW but it has to run RIS. 

With this setup, I can see the grill lighter put out 60Amps depending how far away I am from the target with it.   Scope is not near good enough to see the real signal and I would need to make a better target.  

I also tested a 4-wire sense resistor.  This one is ceramic, rectangle shape.  Also tried a large shunt.   Ran both on the VNA.   Both were very unstable.   I was going to zap them to compare results with the home made target but can't risk the scope.   BTW, after the attenuators, I have a clamp to try and save the scope.  If you decide to play with your own scope, the normal Neon or other discharge tube will be too slow to save the front end of the scope. 

It would be interesting to see the waveforms for the basic MSD, but I can't do it with what I have.     Maybe you can figure out another way.    IMO, simulation may be the cheapest route but you still need to figure out a good model.  



I did see this article on a guy wanting to test plug wires that may be of some interest.  He was running the Nology wires.   No solid data but he does make a good point of there not being any sound data from a dyno.   Maybe Scott can show us their data.
http://mr2.com/TEXT/DavidKucharczyk/ignition.html

Then I found this classic book on line.  I have not read it all yet but its very entertaining so far.  It's on old engines when they used to use the mechanical viberators to fire the coils.   I used to have one of those for a model T or something of the sorts.  Was inside a wooden box!  A modern ignition for the day I'm sure. 
http://books.google.com/books?id=TTVLAAAAMAAJ&pg=PA215&lpg=PA215&dq=measuring+current+through+spark+plug&source=bl&ots=QKcOPmjT7J&sig=hkQAFgIeRffLjIkPF_oPW6aPXx0&hl=en&ei=uLzcSvKnMZCQNrepyasD&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBEQ6AEwATgK#v=onepage&q=measuring%20current%20through%20spark%20plug&f=false">http://books.google.com/books?id=TTVLAAAAMAAJ&pg=PA215&lpg=PA215&dq=measuring+current+through+spark+plug&source=bl&ots=QKcOPmjT7J&sig=hkQAFgIeRffLjIkPF_oPW6aPXx0&hl=en&ei=uLzcSvKnMZCQNrepyasD&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBEQ6AEwATgK#v=onepage&q=measuring%20current%20through%20spark%20plug&f=false

Sorry could not be more helpful.  Would be interested in seeing what you come up with.

Originally posted by shmot   There is small mistake: "The calculated value of energy storage for a 35pF capacitor at 15kV is 1/2CV^2 or about 4 J, well in excess of the storage capacity of the coil itself." Energy is 1/2 x 0.35 x 10^-12 x (15 x 10^3)^2= 4 mJ not 4 J (piko=10^-12).

Good catch!  He is 10X off and you have 0.35pF not 35pF  and manage to get the right answer.     It's pico.    

I had some small PC-104 computers and looked into using one for a logger for the bike.  The power supply and timer boards were cheap but I couldn't find a decent ADC board.  I was going to run headless and just FTP or something to get the data.   In the end it was better just to build one.   Scope would be nice as you can collect much faster.  You may want to check noise specs. before you get into it too far.

I am guessing that the other guy's was a typo as well.   

 

 

Do they have some sort of programmable filter or do you have to add all your own signal conditioning.   For anything I have done with my bike, 10-bit's would do if you can get a full 10.   Even 8-bits would be good for most of tests I have ran.

 

National Instruments was selling a flavor of Labview for the Palms.  There were a few with USB.  I looked into it but they wanted a whole new license for the software.  Cost would have been more than buying a top of the line logger.  You may be able to just code it in C# or C.  I am not sure what they want for the Palm development tools anymore. 

I'm not a USB fan.  I met one of the members who worked on that standard.  Unimpressed to say the least.   I have worked for two companies that tried to use it for products and abandoned their efforts.   The basic problem is there is no common mode rejection.   The devices are DC coupled.   The chipsets are not designed to handle any sort of EMI.   The engineer I spoke with felt that with the two units being DC coupled by the cable, there could be no potential between the two.   He had no concept of RF.  

So, you want to use plug wires that know are going to create a lot of splatter but you want to run USB too.  It's an oxymoron.   My advice is to use shielded cables, buy stock in a ferrite company then test the crap out of it before you head to the track!!   You have your ignition on the bench, so this will be a great way to see how things hold up.

The other thing you may want to consider and test the crap out of is the MC4's trigger input.  It has been my experience that the trigger input can be very prone to noise pickup.  Once it gets lost, it takes some number of pulses to recover as  the bike tries to buck you off.    

Sorry if I'm coming across a bit negative.  Just trying to give you a heads up and maybe save you some time.