[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: DRSSTC question

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

In this case, Don's IGBTs have no internal anti-parallel diodes built in:

""" 
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 
"""

Of course, if one has IGBTs that already have anti-parallel diodes built in, those diodes work perfectly fine. Bare IGBTs will flow current in the opposite direction due to the body diode on the IGBT die, but that will never stand up to our levels of reverse currents. One needs a big reverse diode "somewhere" in there.

Cheers,

        Terry



At 06:41 PM 9/23/2005, you wrote:
The internal diodes on any IGBT seem to be just as fast (if not faster) than the IGBT itself. IGBTs are being made with what seem to be very good diodes built in. People used to disable the internal diode on MOSFETs, but i find that this is unnecessary as well, and that usually the internal diodes are good enough.

Steve

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

In a message dated 9/23/05 3:16:34 PM Eastern Daylight Time,
<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx writes:

>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.

     For a while, wasn't the consensus that external diodes were a
requirement? To not trust merely the internal diodes alone? Or is
this not an issue with the IGBT's used now?

-Phil LaBudde