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Re: DRSSTC question



Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Yes, the reverse diode is *absolutely* required for a DRSSTC. You need an ultrafast recovery diode, and typically one rated similarly to the IGBTs being used. But really, the diode could probably have half of the average current rating of the IGBT and do ok. The peak rating should be good (which most diodes do have very high peak ratings). The diodes might only conduct for a small portion of each RF cycle, and will also conduct many full cycles at the end of the driving period as unused energy is full-wave rectified back to the filter capacitors.

The RURG8060 from Fairchild semi looks like a pretty tough diode, probably big enough to handle most ameture DRSSTC work. Might also want to look at the RHRG5060, which has a slightly faster recovery time.

Steve

On 9/23/05, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: dwb <<mailto:dwb@xxxxxxxxx>dwb@xxxxxxxxx>

When building the bridge drive circuit using igbt's which do not have an
internal antiparallel diode,is it necessary to add one externally?If
required,what are some recommended part numbers?

Don