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Old 07-01-2011, 01:57 PM
valerun valerun is offline
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Default Re: Another DIY DC controller mock

Quote:
Originally Posted by jackbauer View Post
I used a 1uf RC snubber across the switch as i was seeing some alarming ringing on turn on if i remember rightly. My advice would be to use 2 resistors and a schottky diode to shape the turn on and turn off. You really need a hard turn on to punch through the miller knee.
yes, will try that tonight. For the RC snubber, what did you use as R? And how you heatsinked that? From my calculations, at 200V and 8kHz, you would have to dissipate C*U^2*f=10^-6 * 4*10^4 * 8*10^3 = 320W on a resistor (:-0). I can't find anything close to that in a non-inductive package...

Quote:
Originally Posted by jackbauer View Post
What is the ton and toff of the devices your using? Are you using emitter resistors?
ton: 700 ns
toff: 350 ns
I figured if I want to keep switching time to <1% of the cycle, this would mean <10kHz frequency. Now, since I can't really use that blazing toff speed anyway, I have to reduce the frequency to keep the dissipation under control. I hope I can use 5 kHz.

EDIT: oh, yes, I am using emitter resistors.

V

Last edited by valerun; 07-01-2011 at 09:25 PM.
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