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Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
I have used the ZVS for a while, it recently died when I ran it for about 10 minutes, the main cap exploded and a MOSFET fried, anyway, there was an improvement of it by adding 6 turns with 100ohm resistors?
Has anyone does this, on the 4hv flyback page it says it increases efficiency by 35%?
Registered Member #3888
Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649
Uzzor estimated the efficiency at 70-80%, so I don't think the efficiency could go up 35%. The wiki specifies that it increases performance by 35%, and since it's adding extra windings in parallel I would assume that it means that the output is increased by that factor. This would mean that even more power would be drawn at the primary side and probably explode your parts even faster.
Try using a MMC of PP box caps to spread out the heat between them. Higher current rated ultrafast diodes might help too. Another recent consideration that I've read about with the ZVS is the inductor and how if it saturates it could lead to self destruct mode. For this reason you might want to make a new inductor if you're putting a lot of power into the circuit. If you don't have a larger toroid then you could use a ferrite transformer core. If you're using more than a 12v input you should also increase the gate resistors from 470 ohms to something higher.
Registered Member #4118
Joined: Mon Oct 03 2011, 04:50PM
Location: MD
Posts: 140
I'd say use resistors of about 1k. I don't believe that adding those 6 turns with 100R resistors could help. The resistors would just waste energy... I wouldn't trust the wiki on everything. It even says "The "47-200 µH" inductor is customized to the desired output of the FBT. In general, if one requires more voltage output, he should use a larger inductor. For more current, use a smaller value inductor." The inductor doesn't affect performance at all, it just keeps the ZVS working. The way to change output voltage is change the turns ratio, so changing the number of primary turns.
Registered Member #3926
Joined: Fri Jun 03 2011, 08:32PM
Location: UK.
Posts: 525
m4ge123 wrote ...
I'd say use resistors of about 1k. I don't believe that adding those 6 turns with 100R resistors could help. The resistors would just waste energy... I wouldn't trust the wiki on everything. It even says "The "47-200 µH" inductor is customized to the desired output of the FBT. In general, if one requires more voltage output, he should use a larger inductor. For more current, use a smaller value inductor." The inductor doesn't affect performance at all, it just keeps the ZVS working. The way to change output voltage is change the turns ratio, so changing the number of primary turns.
I tried to increase voltage output of my ZVS by using different inductors, but there is no difference.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hey platinum, perhaps you should consider a half bridge driver with a TL494 instead? You already have some HV mosfets and you can get practically all other parts from a dead ATX PSU! You could even wind the GDT onto one of it's cores.
Of course it'd be a big learning curve, but I assure you it's "the right path" you should consider for a flyback driver.
Mazzili driver has never really held a particular reliability mark, especially if it's caps are undersized and melt themselves after a while!
I find it silly to use just a single capacitor under such high reactive power tortures - I'd use at least several 100..300nF caps in parallel.
Yes, there have been full bridges with flyback transformers. Not long ago I have demonstrated a full bridge driver for flybacks (among other things). I believe you have seen it.
Personally I would skip the half bridge and go directly to a full bridge. If you can drive correctly 2 mosfets you can drive 4.
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Improving the ZVS?
