I'm building a rectifier to rectify a 3-phase signal for part of a school project, so I'm not working at these power levels without help and supervision.
This seems to be an appropriate circuit as far as the rectifying goes, but I have some questions. I've found that choosing diodes based on their datasheets isn't as straightforward as I anticipated. The system I'm dealing with handles a lot of power; specifically, it has to handle max values of 40V and 40A, or 1.6kW of power.
I'm interested in achieving maximum power transfer, so I want to minimize the diode forward voltage drop. For that reason I've been looking mainly at Schottky diodes.
Here is a link to the datasheet to a diode that may be suitable. And here is a summary of the important specs:
Max forward voltage drop (@ junction temp = 25°C): .48V
Peak repetitive reverse voltage: 45V
Average rectified output current: 12A
Non-Repetitive Peak Forward Surge Current 8.3ms Single Half Sine-Wave Superimposed on Rated Load: 200A
The peak repetitive reverse voltage makes sense regarding how much voltage the diode can handle, but the maximum current rating is a little ambiguous to me. What does the last parameter mean exactly? It seems like the diode can handle up to 200A as long as it's not held at the limit for too long. But how can this value be so large while the average rectified output current is only 12A? Either way, it seems like this diode won't do since it can only handle 12A on average.
I couldn't find a direct link for the next diode's datasheet, but it's the first hit on Google via this link. From what I've seen, I think you would call this a "dual" Schottky diode. Here is a summary of the relevant specs:
Max forward voltage drop (@ junction temp = 25°C, forward current = 60A): .90V
Peak repetitive reverse voltage: 200V
Average rectified output current: 75A
Non-Repetitive Peak Forward Surge Current 8.3ms (@ junction temp = 45°C): 600A
First off, is it common to use these "dual" diodes for this kind of thing? The forward voltage drop seems very high for a Schottky. Is that for both diodes in a forward-biased state? The datasheet does say that all ratings are "per leg", so my guess is no. Besides that, I this diode more than able to work with what I'm trying to do.
I'm still searching, but those are the only good candidates I've found so far. It's easy to find diodes rated for either high current or high voltage, but not for both. Why is that?