Fligh High wrote:
Sure , I think I understand the silicon/bond-wires limits , but in real life use wouldn't 2 x Irfp4368 be the same current-handling wise as 1 Ixys if they reach "working" temperature in practical use ?
How would you program the max phase current-limit in a controller btw , because it can't be a fixed 500 amps in case of the Ixys because it is less capable when temperature rises but the 2 TO-247 Irfp4368 limit can be set allmost to a fixed 390 amps because of the plateau (all veeerry loosely compared of course)
Yep, the IRFP4368 is a very very good FET in a nice package, I based my controller design around it's 100v brother, the IRFP4468, which is also outstanding. The 4468, as well as the IXYS gigamos TO-264 series FETs are what I based my previous controller FET stages on, because they kick ass. Unfortunately, when switching these current levels, the inductive path becomes a huge factor in controller design and the ability to share current effectively at high PWM frequency (required for the low L+R motors) as well as complex cooling and cap layout/packaging needs. The only option to go beyond a 12-fet design and keep it inductively balanced is to use radial FET arrangements, which is the path I took on my controller layouts, because my linear layout design experiences (like my cell tester, which uses 8x IRFP4468s in linear parallel) taught me it's a fool's game to play with these current levels.
With this FET, the inductive path from having the entrance and exit on opposite sides, along with the sinking opposite to the connection side just makes these things a damn dream to layout!
You can do a 6fet layout neat as a bugs ear with an inductive path that would make an RF engineer happy, and 12FET designs are equally fantastic, not to mention so much easier to construct than the radial designs. These things have seriously made my last few months of work on FET arrays seem like huge waste of time, because it's effortless to just bolt these things down to the backside of a CPU sink and have a beautiful and balanced compact simple and superior inductive layout.
TO-247 and TO-264 both are very good, worlds better than TO-220. However, this thing just dominates from the angles those packages miss on.
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