Half bridge capacitors

[flyingperson23]

For a half bridge, do the DC blocking capacitors (C4,C7) have to be rated for the RMS current passing through them? I can't find any suitable capacitors with an RMS rating above a few amps, and DRSSTC use passes at least a dozen RMS amps through them. Are there some special capacitors with a much higher current rating, or a reason why high current rating isn't needed?

[davekni]

If C3 is large, then C4 and C7 each carry half of primary current.  If C3 is tiny and supply is high impedance (wiring inductance to bulk caps or whatever), then C4 and C7 each carry 70% of RMS primary current (sqrt(0.5)).

or a reason why high current rating isn't needed?

As with most TC components, over-driving to some degree is common.  Parts are spec'ed for thousands of hours of continuous use.  TCs often get only a few hours of use in their lifetime.  Also depends on cooling air flow and how long TC is operated in any given continuous run.

[Mads Barnkob]

This we discussed, not that long ago, about DC blocking capacitors C4/C7, maybe you can use some information from that thread: https://highvoltageforum.net/index.php?topic=2348.msg19226#msg19226