Gentlemen,
Now we are getting down to the challenging aspect of this reverse engineering effort. How does an H-Bridge switch control a parallel resonate tank circuit to dead line an oscillatory process and then start it up again 180 degrees out of phase?
I thought there would be some novel timing trick found in the logic controller, such is not the case. So far we only have a simple pulse train and its complement. When you hit a tank circuit with a single saw tooth current pulse it does just what it is suppose to do. It rings like a bell. Even the application of a second pulse of reversed polarity only complicates the response (at least so far). This leads me to consider two situations:
1. There is additional control logic to be found on the H-Bridge card (I doubt it because experimental tuning and adjustment would be difficult)
2. The response of the secondary tank on the primary tank circuit is more profound than we are generally exposed to. This is complicated by the novel magnetic circuit.
The syntheses of the proper waveform from multiple signal generators is probably not going to offer much of a solution. We need to have the forcing function develop inside the transformer.
Any Ideas?
Spokane1
This is all I've come up with so far
This is still a very good question. If anyone has purchased the MIT video, are there any hints regarding how this is done? To me the transformer design has very high leakage inductance primary to secondary due to the topology (magnetically a widely separated primary and secondary, gaps etc.)therefore, even if the secondary were shorted during the dead time it would not quench the oscillation on the primary so effectively, we should see a ringdown due to the leakage inductance. This leads me to believe that there is nothing happening on the secondary that can quench the oscillation so effectively. It may assist, but would not alone produce the tiny damped oscillation we see in the scope shots. Could it be the H bridge that is shorting the tank + swinging choke with a third cycle on the timing diagram where both the grounding Fets in the H bridge are kept on during the dead time cycle?
It is my belief that the basic circuit can be back engineered from a very careful analysis of the scope shots. Additional circuit info is a bonus and fills in some missing pieces. The elusive factors will be the exact magnetic circuit and materials. Your important observation and question needs a good answer. I might add that the DC output from a uniquely wound transformer is what Steve Marks achieved in several stand alone units of very high power.Consider this: The ordinary magneto ignition system on a old style gas engine lawn mower motor uses a fly by magnet to induce a current into a coil which remains shorted by the points. At the appropriate moment, the points open and a HV DC pulse appears on the secondary. Normally this pulse rings with the distributed capacitance and the capacitor across the points to turn the DC output pulse into an HV oscillatory damped wave, but the DC could also be captured with a flyback diode and dumped into a capacitor. Some folks used a DC restorer circuit on the primary to present a single DC burst on the HV coil output rather than an damped ringing wave. This supposedly created a hotter spark from a unidirectional pulse. In GG's device it seems (in comparison) that the fly by magnet is replaced with a primary tank circuit to charge the magnetics. GG opens the (points aka FET's) on the secondary at the appropriate time to release some, but not all of the stored current flowing in the coils of the magnetic circuit. Regards, ION
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Topic: Graham Gunderson Energy conference High COP demonstration (Read 235671 times)
