Pierre's 170W in 1600W out Looped Very impressive Build continued & moderated

[konehead]

Hi Dog- one
I looked up parametric resonance and the word parametric comes from "parameters" so you could maybe say parametric is similar to "changing the parameters"
Anyways one analogy I read about with resonance is someone on a swing, and to get more power and greater length to swing, the person on swing will stand up and sit at points on swing to create a stronger swing... so sort of vertical actions applied to horizontal swing motions using weight and gravity at cost of more physical effort to get more power into the swing. (whatever eh)


Anyways about super cap working as very heavy load to create a shorted condition, I would think not a drained down super cap bank, but instead like Pierre does, pre-filled super caps which will accept and store the energy easily, and still have the inductor "see" this load as a short (very heavy load) but not so heavy that it becomes a brick wall to the extra energy produced and cap will not full any faster or higher or fill at all...so sort of perfect world in cap's internal resistance is needed where inductor sees a short and cap size just right so it works as receptor and "resonant chamber"
I would guess if Pierre did not pre-fill his caps his DZ generator would not work at all...

[listener192]

A couple of points about the BTS7960B bridge boards.
They are missing a recommended 270nf cap across the supply rails close to each device.
Overvoltage protection kicks in at 27.5V which turns on the HSS and turns off the LSS.

If this gets invoked, then other LSS's will be on sequentially throughout the switching sequence, effectively causing the on HSS device to conduct current continuously.
This is not desirable behavior in this application.
The later  BTN8962TA device that replaces the BTS7960B, does not have this feature, relying only on thermal and current limitation.

The BTN8962TA pulse current rating is higher than the BTS7960B however, the continuous current rating is only 30A compared with 40A. Otherwise the the later device is pin for pin compatible.

A few weeks ago I had a mysterious failure of a single high side device , while the supply was increase to 30V and I attribute this to the over-voltage protection. The device in question had a permanent HSS short afterwards.

Just a warning for anybody using these boards that wants to increase supply voltage, to achieve the same current at higher switching speeds.

L192

[listener192]

In an AC generator, with a DC energised rotor, the flux splits and travels round the stator to the opposite rotor pole, largely closing the flux.
In the DZ generator, each adjacent pole pair is energised at the same time. With a N and S in registration with the rotor, some of the flux will tend to close through the airgap between the adjacent pole rather than close through the stator to the opposite pole. This is a large difference between the generator types.

Experiment:
If you remove 2 poles, 1  from either side of the stator and then switch the remaining poles back and forth i.e. clockwise then anti-clockwise,  the poles will always couple flux fully through both sides of the stator and across the rotor.
Rotating the poles continuously in the same direction would just use more switch steps than required, as rotor induction only need be over a limited angle of arc. Some pole separation would decrease the flux cancellation.

L192

[listener192]

Here is a drawing of the diodes in action that Pierre drew on the back board in one of his videos.   You should see why we have to shut off the field in rotation now.  Keep the code the same using overlap mode.  This also explains why you do not want the coils in series.  You want to isolate the field(s) and you can run them in parallel.

No the field is not shut off in rotation. This waveform shows a pulsed signal riding on top of the output sine, these are not recovery pulses, although as there is pulsing, there could be recovery current via the switch body diodes.

Attached is a simplified drawing of how this could be achieved.
Only a few MOSFET switches shown for clarity. Coil connections and switches remain unchanged only the supply rail is modified.

This could be accomplished with one relay or two MOSFETS.

L192

[Andy71]

Yes exactly
That's how I built it a few weeks ago.
For the coils to fully drive through please use PNP and NPN FET types.
I send you the circuit diagram again.