Ghazanfar Ali Generator - Utlilizing trapped energy

[Mannix]

Ali,

I apolagize for the poor reference of mine

The trouble with refering to batteries is that their chemistry changes and confuses so many people  even the mention of batteries gets my attention in a negative way .
The vast majority of people have no real  idea or experience of how batteries  rise in voltage with load and so many ignorant claims are made along those lines .

Your device on the other hand is designed to sustain of a capacitor  ..absolute proof .. no sums required and i was upset that a battery would play any part other than the drive .There is no issue with the drive because it is easy to use series resistance there

I have buit a version with 3mm wire and a 6" torroid heavy guage  short connections ..and my stack of 4 irfp264 fried instantly with 40volts in the cap.
interesting to say the least .





All , Its is best to stay with multisim in this thread if possible ..yes we know it should not work but it will at least give everybody a cohesive  reference point

[duff]

.

[gyulasun]

...
I have buit a version with 3mm wire and a 6" torroid heavy guage  short connections ..and my stack of 4 irfp264 fried instantly with 40volts in the cap.  interesting to say the least .
...

Hi Lindsay,

I wondered on your fried 4 MOSFETs and decided to do some calculations.  I assumed 3 meter wire length for your coil from the 3mm wire, it may have 0.00712 Ohm DC resistance  (I used this calculator here: http://chemandy.com/calculators/round-wire-resistance-calculator.htm )

For the MOSFETs ON resistance, they have 0.075 Ohm each (from data sheet), 4 in parallel may have had 0.01875 Ohm (assuming the 4 FETs were equal).

Now the inner resistance of your 4700uF capacitor i.e. its ESR (Equivalent Series Resistance) value what we are also interested in and here is a link ( http://kakopa.com/ESR_meter/ )  where there is a table for the ESRs for different capacitor values, I chose the normal value: 0.026 Ohm what I rigorously rounded up to 0.03 Ohm to account for all your short connections too. 

Now the approximate peak current taken from the capacitor (charged to 40V) is I=40/(0.03+0.01875+0.00712)=40/0.05587=715.94 Amper.  This is too much for the MOSFETs because even if I consider their absolute maximum pulsed drain current of 4 times 150A (assuming fully equal ON resistances--unlikely they had), it would give 600 Amper (data sheet is here: http://www.vishay.com/docs/91217/91217.pdf where the 150A pulsed drain current rating is tied to pulse duty cycle, see Fig. 11).

If you had less than 3m long 3mm wire than the peak current could have been higher than 715A.  And at current this high the coil core could have been saturated too (as Duff hinted at) so the coil's inductive reactance at the switch ON moment was way less than 376uH,  I mean very little LC tank reactance against the increasing current to be able to do useful current limit.

IF your 4700uF capacitor is an older type than its ESR value may be higher than what I considered, then the total current is proportionally less (say ESR=0.05 Ohm instead of 0.03 Ohm, then the peak current would be I=527.2 Amper, still a huge value to destroy the lowest ON value MOSFET first.   Indeed your failed test brought interesting learning.

Gyula

[broli]

Hi Lindsay,

I wondered on your fried 4 MOSFETs and decided to do some calculations.  I assumed 3 meter wire length for your coil from the 3mm wire, it may have 0.00712 Ohm DC resistance  (I used this calculator here: http://chemandy.com/calculators/round-wire-resistance-calculator.htm )

For the MOSFETs ON resistance, they have 0.075 Ohm each (from data sheet), 4 in parallel may have had 0.01875 Ohm (assuming the 4 FETs were equal).

Now the inner resistance of your 4700uF capacitor i.e. its ESR (Equivalent Series Resistance) value what we are also interested in and here is a link ( http://kakopa.com/ESR_meter/ )  where there is a table for the ESRs for different capacitor values, I chose the normal value: 0.026 Ohm what I rigorously rounded up to 0.03 Ohm to account for all your short connections too. 

Now the approximate peak current taken from the capacitor (charged to 40V) is I=40/(0.03+0.01875+0.00712)=40/0.05587=715.94 Amper.  This is too much for the MOSFETs because even if I consider their absolute maximum pulsed drain current of 4 times 150A (assuming fully equal ON resistances--unlikely they had), it would give 600 Amper (data sheet is here: http://www.vishay.com/docs/91217/91217.pdf where the 150A pulsed drain current rating is tied to pulse duty cycle, see Fig. 11).

If you had less than 3m long 3mm wire than the peak current could have been higher than 715A.  And at current this high the coil core could have been saturated too (as Duff hinted at) so the coil's inductive reactance at the switch ON moment was way less than 376uH,  I mean very little LC tank reactance against the increasing current to be able to do useful current limit.

IF your 4700uF capacitor is an older type than its ESR value may be higher than what I considered, then the total current is proportionally less (say ESR=0.05 Ohm instead of 0.03 Ohm, then the peak current would be I=527.2 Amper, still a huge value to destroy the lowest ON value MOSFET first.   Indeed your failed test brought interesting learning.

Gyula

Good analysis you did there.

[27Bubba]

Hi Lindsay, I thought Ali mentioned wire size used on coil was 18 Avg =  1.024mm diameter wire. Hope this helps. Sorry about the Mosfets.