I am building an HV supply consisting of several stages with buck-boost CCFL converters.
I'll be posting this in detail quite soon so you can see progress - but first I need to order the HV components (from China/ebay)!!!
What I am building looks like this, with 10 stage;
Two issues I am facing, for safety and circuit protection;
1) Each stage mustn't exceed 3kV else the total chain will exceed the values of the coupling capacitors, yet could reach 5kV when unloaded. I can simply add a resistive drain on it to rein back the voltage, but are there any straightforward less lossy ways to limit each stage to 3kV? - e.g. is there such a thing as a 3kV Zener diodes or transorbs!?! Or would regular diodes work?
2) The stages are each fed separately but capacitively isolated from one power inlet. The risk is that if a capacitor fails in the chain then it could dump the stage voltage to the power inlet. What are the best means to couple the power inlets together such that if they diverge by more than a hundred volts or so (an HV transient short trying to get out) then it'll be shorted within the HV supply? e.g. are regular transorbs quick enough to stop an HV spike getting on to external lines, should I be thinking about using some form of spark gap, or are there recommended TVS components in the face of potential multi kV pulses? Or all three together - or more!?