Adjusting drsstc phase lead.

I am adding some phase lead to my drsstc circuit to overcome the fairly large delay of the IGBT. This should solve the ringing problem finally, which has killed some brick IGBTs including a cm300 and a cm400. Sure, you have to break some eggs to make an omelet, but these are some damned expensive 'eggs'!

The idea was taken from Finn Hammer's 'Thumper'. It was a circuit he called the 'prediktor'. My circuit is somewhat simplified, as i only included the inductor with associated burden resistor (potentiometer in my case) instead of the dead time generator and other circuitry Finn used. See the thread of 4hv here: http://4hv.org/e107_plugins/forum/forum_viewtopic.php?68820.0

Category:

Science & Technology

Tags:

• high
• voltage
• frequency
• phase
• dual
• resonant
• solid
• state
• tesla
• coil
• drsstc
• sstc
• igbt

[Tab54o]

Hey are you using a variable inductor on yours? Also have you tried using the phase lead shit on a half bridge. I cant get one of my boards to work on a half bridge. Never had a problem before.

[triggerhappy77707]

@Tab54o In this video i used an air core inductor and a pot, but it always seemed to work best with the pot set at its lowest resistance, so now i use a carbon film resistor and a rewound variable inductor. I got the inductor from some old TV board (the kind with the threaded ferrite tuning slug in the metal can) and rewound it with around 22 turns of 32 gauge and it works fine. Now i have it set at a higher res freq and the waveform is around the same, and it ran 620 amps seemingly fine.

[triggerhappy77707]

@Tab54o Oh i forgot to mention i am using a halfbridge in this video. Without the phase lead shit, i killed a few IGBT bricks, and i haven't killed another one since using it. Finn Hammer is who i got the idea from, and Steve Ward used phase lead for his new driver board.

[Tab54o]

Ya know your bridge looks fine I dont see how youd have excessive ringing on that.

[triggerhappy77707]

@Tab54o Im assuming it is caused by the freewheeling diodes conducting. Finn Hammer's system showed the same amount of ringing with no phase lead.

[Tab54o]

Or maybe it was just too high frequency for the bricks. 

[triggerhappy77707]

@Tab54o Oh, and you may have thought the freq was high because my cap bank looks rather small, but it is 680nf@6.4kvdc of CDE 942c series.

[Tab54o]

@Tab54o I figured out my problem. My first board had an on board interrupter, the second didnt, the off board interrupter i had the voltage clipped to 5v with two diodes. It was casing the voltage on the phase comparator to ramp up and down and was fckign with the quality of the output signal lol. Now I just need to find a proper inductor.

[Tab54o]

@triggerhappy77707 Well I use phase lead too in my own driver design but only on one coil and the other day i built another board and could not get it working on a half bridge ended up switching it out for a regular driver. It must be that particular board my first one works fine.

[Tab54o]

@triggerhappy77707 Yeah it did look kinda small.