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IGBT for 100kHz Half Bridge?

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Sorry about this, just got a bit more time to look at the PCB. The 100khz is actually the freq of the flyback that gives the hi-side drive supply for the IGBTs. The half brige IGBTs are being driven from a ribbon cable from another board, via a fairchildsemi 3180 opto driver. There are 4 HB IGBTs (2 pllel pairs)...IXER35N120T.

Each IGBT has a gate_emitter P6KE18CA...surprising when you think IXER35N120 has VGE max of 20V


So this is a 7.2kW Half bridge (definetely half bridge) switching off the output of a 3 phase bridge from UK mains. Vout is 12 to 24V. There is no output inductor...just seven torroids round the busbar that leads to the output caps. (20mF of output caps)

Primary side rail splitting caps are each 12uF...they look like motor run type caps. Cylindrical Approx 3.5cm diam and approx 9.5cm long.

I removed the transformer from this PSU. It was using 4 E core halves. (so two closed cores, side by side) Each E core half was of dims 55mm length, 25mm thickness, and 28mm "height". The centre leg was "cuboid" (not rounded), and of width 17mm. The "side legs" are 9mm thick. The bobbin was not one of the standard ETD, or PQ things. Connection from IGBT PCB to transformer is two ~15cm wires which arent twisted, and certainly dont sit tight side by side along their length on the way to the transformer.

Primary side CST is in the bridge and is approx 3cm by 2.5cm by 1.8cm high...its output seems to go off down the ribbon cable to the other PCB.

Primary IGBT gate_source snubbers are 100p---[3 pllel 1k]...2 of these, one for each IGBT pair.
(the 1K's look like 1W axials) They are ringed brown/black/black/brown/brown so they could even be 110R, but i went for the 4 rings that were kind of closest to each other and so said 1k)

What switching frequency would you say was likely here for this 7.2kW Half Bridge SMPS.? (Sorry we're not allowed to scope it, or run it without its metal cover on)

BTW This is the first thread on this
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Thanks, sorry i meant its a Half Bridge with power of 3.6kW......i keep forgetting...there's 2 in the box...with a total power of 7.2kW when they are paralleled....but i presume you would still go for around 20kHz switching frequency?

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