At 05:03 AM 9/1/2003 -0400, you wrote:
>Thank you for the confirmation :-) But that still leaves me uncertain of the
>best way to create this high gate drive voltage. The only way I can see at
>the moment is to create an additional isolated supply and reference its
>ground to the emitter of the high side IGBT. And duplicate this again for
>the second IGBT. This seems like an excessive hardware solution, is there a
>better way?

Two charge-pump drivers fed by each half-bridge drive signal itself is
possible,
but 100% duty cycle isn't possible, since there would be no charge being
pumped if the half-bridge isn't switching. This circuit is used in some
integrated high-side drivers (eg. IRF).


              +15  o
                   |
                   V eg. UF4005
                   -
                   |
           +-------+       +Vbr
           |       |
           |       |         |
           |      |\      ||/
          +|     -| >-----||    IGBT
          ---     |/      ||>
          ---      |         |
           |       |         |
           +-------+---------+----------
                             |
                  +15        |
                  |\      ||/
                 -| >-----||    IGBT
                  |/      ||>
                   |         |
                   |         |
                  ===       ===
                  GND       GND



Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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