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Chuck norris flyback driver

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Ash Small

Tue Jan 18 2011, 12:50AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Pokemon, as we've already pointed out, you want high wattage, high amperage mosfets.

I imagine 1000v will push ~1000amps, maybe more, through the primary (and mosfet). At 50% duty cycle that means ~500 amp mosfets minimum.

(these figures are guesstimates)

8 amp mosfets will blow almost instantaneously.

Arcstarter

Tue Jan 18 2011, 01:19AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

The voltage the mosfets will see is 3.3 times as high as the voltage put into the driver. That makes a 960v ZVS driver completely impossible, unless you know of some 3kv fets or use a cascade.

Current is not a problem, the more turns on whatever core mean less current it will try to pull, ohms law.

What is wrong with 170vdc or 350vdc? There is no reason at all to make a higher voltage input driver, and then, the ZVS becomes impractical at the power that you would push at 960v at any appreciable current.

Ash Small

Tue Jan 18 2011, 01:31AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Arcstarter wrote ...

.Current is not a problem, the more turns on whatever core mean less current it will try to pull, ohms law.

.

Yep, until you reach the point where output voltage = input voltage. (more likely if you are winding your own secondary)

EDIT: I've been looking into using 380 V on the primary, but it looks like this will be too high.

Myke

Tue Jan 18 2011, 02:37AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Way before you reach that point, you will run into problems. As the driver voltage increases, so does its tendency to go into parasitic oscillations. It's when stray inductances and capacitances resonate somewhere throwing the entire operation off. These start to appear around line input voltage but can appear lower.

As the Vds goes up, so does the other values you don't really want to go up for ZVS operation. Things such as gate capacitance and turn off times. I may be wrong though.

ubuntupokemoninc

Tue Jan 18 2011, 02:41AM

Banned on 1/22/2011 for repeated rule violations after multiple warnings.
Registered Member #3299 Joined: Sat Oct 09 2010, 08:11PM
Location: Bantown, USA
Posts: 220

Kay so rectified mains will work. I CAN'T WAIT TO START KILLING FLYBACKS

Coronafix

Tue Jan 18 2011, 07:28AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

What would the use of such a thing be?
I mean, it would seem pointless to me to spend so much time, energy and money on such a thing just to see if I could do it.
Don't get me wrong, go for it. Do it. Go on.
How many flybacks do you have?

Dr. Dark Current

Tue Jan 18 2011, 09:47AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

You can push more current at less voltage and get the same power. When flybacks die at 40 volts input to the ZVS driver with cool transistors, I think there is no need for a mod... If you want to power more transformers from single driver, use bigger MOSFETs or IGBTs. IMO it is not practical to go over ~100V DC with this driver.

Bjørn

Tue Jan 18 2011, 04:17PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

There have been complaints about the quality of this thread. The whole idea is completely ludicrous and the quality of the posting is not acceptable. In addition you break almost every rule we have about posting.

If you don't understand the basic principles you learn them before posting threads like this.

Steve Conner

Tue Jan 18 2011, 05:04PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I say we ban him for using the "Name Of Chuck" in vain.

Arcstarter

Tue Jan 18 2011, 09:18PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Dr. Kilovolt wrote ...

You can push more current at less voltage and get the same power. When flybacks die at 40 volts input to the ZVS driver with cool transistors, I think there is no need for a mod... If you want to power more transformers from single driver, use bigger MOSFETs or IGBTs. IMO it is not practical to go over ~100V DC with this driver.

I agree to this mostly, but i think a mains driven 'ZVS' is practical, because it seems awfully pointless using a transformer to get the voltage needed to drive another transformer

. To make this driver run off of mains, a 600v device is pretty near the bare minimum needed to allow for some headroom, but you can easily get that with an IGBT.

I agree with Bjorn, if the point of using higher input voltage is to get higher output voltage, why not use less primary turns to get a higher step-up ratio? Sure it would require more current, but that is sort of IGBT's strong point, a small device can handle quite a lot of current. Good luck finding a TO-247 mosfet that is made for 60 amps and 600v!

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