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Registered Member #834
Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644
I have used strings of 1N4007 diodes for low-frequency applications without equalization, and they work as expected or better, with low leakage, and very uniform maximum voltage. One string failed, probably due to excessive reverse current, since they are not avalanche rated. The failed diodes look normal, but their leakage current is measured as much higher that the normal.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ash Small wrote ...
Proud Mary wrote ...
I think all EE courses should have an industrial economics module, because 99% of real world EE is concerned with manufacturing products or providing services which must compete in the marketplace.
It's called 'Production Engineering' (part of most engineering courses), something which most 'academics' have little time for...
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
Resistors only take care of the static voltage sharing any way ... not the dynamic voltage sharing during turn off.
If you didn't have all those diodes I'd say just go for avalanche rated ones ... since you do, just add more and hope for the best. Given all the dynamic processes inside the string (lots of Ls, lots of Cs, lots of diodes snapping off suddenly and at different times) trying to calculate anything by hand would be futile ... and diode models in simulators aren't generally accurate enough to model reverse recovery.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Pinky's Brain wrote ...
Resistors only take care of the static voltage sharing any way ... not the dynamic voltage sharing during turn off.
If you didn't have all those diodes I'd say just go for avalanche rated ones ... since you do, just add more and hope for the best. Given all the dynamic processes inside the string (lots of Ls, lots of Cs, lots of diodes snapping off suddenly) trying to calculate anything would be futile ... and diode models in simulators aren't generally accurate enough to model reverse recovery.
These are the things I worry about, and why I ask for many oppinons.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
I would've liked to use strings of diodes-in-series too...but for the PITA of making the circuit boards and drilling so many holes and having to solder so many pieces...I decided not to.
Too bad someone doesn't sell circuit boards designed for this purpose, already etched and drilled.
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