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Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Hi all, here's another my SSTC idea from the "SSTC - Super Simple Tesla Coil" series . The idea is basically that a halfbridge (or fullbridge -but that's not simple enough ) is switching at a frequency several times lower than the secondary's resonant frequency. A series LC-circuit, with "L" being the primary winding, is connected to the output of the halfbridge. This circuit is tuned to resonate at the same frequency as the secondary. Every time the halfbridge "switches over", the primary tank circuit starts to oscillate, exciting the secondary. Output power can be varied by changing the frequencyof the halfbridge. Now please tell me why this wouldn't work
Registered Member #795
Joined: Mon May 21 2007, 06:04PM
Location: Bocholt, Germany
Posts: 35
I think its no problem to fire a TC with a lower frequency than the resonant frequency, but what is the advantage? Just that you can use slower semiconductors?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Crow187 wrote ...
I think its no problem to fire a TC with a lower frequency than the resonant frequency, but what is the advantage? Just that you can use slower semiconductors?
Advantages I can think off -you do not need any feedback circuits so the whole circuit is kept simple -you can use slower semiconductors -because the halfbridge frequency is low, you can use a halfbridge driver chip (such as IR2153) to make the circuit even simpler, this would be literally a few component DRSSTC!
I can imagine you would need high pulse current transistors to get some power from the coil. I'll try this circuit in the near future with some IGBT's, hopefully I'll see at least some sparks
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
There would be no advantage of this except eliminating shot trough condition.
If you use 50% deadtime IGBT's would need to withstand 2x longer on time to produce equal spark. And contrary to this most people seem to find best to pump the energy into secondary in shortest amount of time, deliberately using low Q tanks and short on-times.
Drive logic would need to be complex, it would produce larger delay and zero current switching would be poor.
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Either 1) you only drive it at 1/2, 1/3, or maybe 1/4 Fres, in which case you will still require zero current switching synch up, or 2) you drive it at such a low frequency so that the primary oscillations are basically damped out before the next switch, but this would lead to very little power throughput, making it pretty underwhelming i think.
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(DR)SSTC circuit idea
. 
) is switching at a frequency several times lower than the secondary's resonant frequency. A series LC-circuit, with "L" being the primary winding, is connected to the output of the halfbridge. This circuit is tuned to resonate at the same frequency as the secondary. Every time the halfbridge "switches over", the primary tank circuit starts to oscillate, exciting the secondary. Output power can be varied by changing the frequencyof the halfbridge.
