Adding Better Diodes
I’m currently bypassing the slow reverse recovery diodes in the IGBT bricks with much faster minibrick diodes.
I am adding a diode to the IGBT path to turn it into a switch that blocks both directions, and conducts in one direction when on, then adding a fast diode across that assembly.
The blocking diode doesn’t need to have a voltage standoff rating of the full bridge, because it is in series with the IGBT brick which can stand off the full voltage. Ideally I would use the highest current and fastest diode available, with no regard to standoff voltage. Since a friend had some laying around, I used some DSEI2x101 minibricks for this.
For the bypass diode, full voltage standoff is required. For this position, I’m using ST 12012TV1 diodes.
I’m a bit concerned about passing all this current through these diodes, but it is well within the pulse and I^2S rating of the components so hopefully it will be fine. All the minibricks will be heatsinked to busplates.
Some shiny pictures of the modifications in progress: