Kapanadze Cousin - DALLY FREE ENERGY

[itsu]

First result with my non dissipative snubber instead of the Oleg snubber.
I still have the RC snubbers in place and varistors (140V clamping) across the drain / sources.

I am in resonance with a 40W bulb on the Grenade output, pulling almost 6A from my 24V battery stack.

Further results and video later tonight but it looks better then the Oleg snubber, nothing gets really hot, just somewhat elevated temperatures

Yellow and blue traces are across the both MOSFET drains.


Itsu

[Void]

Hi Itsu. That's looking pretty good. I am not clear if you are using two
non-dissipative snubbers, one for each MOSFET?

I will reconnect my 10uF cap at V+ and retest to see if any of my UF4007 diodes
still get hot now that I have the varistors connected in.

All the best...

[itsu]

Hi Itsu. That's looking pretty good. I am not clear if you are using two
non-dissipative snubbers, one for each MOSFET?

yes, both MOSFETs have their own snubber, (1mH inductor (choke), 0.1uF cap and 2 UF4007 diodes).
Both snubbers put together on 1 small pcb inbetween the MOSFETs and yoke.

Itsu

[Void]

Hi Itsu. Ok, thanks for doing that test. It is helpful to compare results.

My UF4007 diodes still get too hot when I connect the 10uF back to V+,
expecially the D3 and D4 diodes. I get a lot cleaner waveform and better
spike reduction with the 10uF cap connected however. I think my varistors
do not have a low enough clamping voltage however. The max clamping voltage
for my varistors is listed as 250V, so I think I will have to get some varistors with
a lower max clamping voltage.

Also, I wonder how the non-dissipative snubbers would work if the value of C is reduced somewhat.
I may try that, as it may be a way to reduce the current in the diodes and keep them cooler.


All the best...

[itsu]

I removed the RC snubbers from across the drain / source of the both MOSFETs which caused the ringing to return, see screenshot 1.
For comparison with when the RC snubbers are installed, i have also put up the screenshot with both the RC snubbers in place as the new non dissipative snubber, see screenshot 2

So the non dissipative snubber is able to tame the spike, but not the ringing, so we need both if we want a nice square wave like signal.
Perhaps Nick likes to have the ringing back, then he can remove the RC snubbers and try the non dissipative snubber only.

I do not see much difference when using a battery stack (24V) or a 24V / 10A PS with added filtering.

Temperature measurements show some elevated temperatures, but it stabilizes around 45°C (113°F) for the D1 and D2 diodes.
The inductor get the most hottest at about 60°C and climbing.

I will try some schottky diodes, but i think that this non dissipative snubber setup will protect the MOSFETs enough to be able to run it for longer times
allowing some further tests,  however.......it seems that Nick's setup behaves somewhat different then Voids and mine, so  there are no guarantees


Video here:   https://www.youtube.com/watch?v=8KFHiR8MJFs

Regards Itsu