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We have the following generator: Permanent Magnet Generators. For the project we would like to use this converter. Between this generator and converter we've to convert the three phase voltage to an useable DC voltage, and we want to do that with a three phase full wave rectifier. According to wikipedia there are a few types of that kind of rectifiers. Can some of you that has experience in this field give us the right path to follow.

Important is that the rectifier has to be able to handle the current that passes trough it.

For the output voltage of the generator, we got the following data from it:

enter image description here

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  • \$\begingroup\$ For the generator: (futurenergy.co.uk/accessories.html) \$\endgroup\$ – KlaasP Dec 19 '16 at 19:15
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    \$\begingroup\$ Is there some reason you don't use their recommended 3 phase rectifier box? \$\endgroup\$ – Jack Creasey Dec 19 '16 at 19:44
  • \$\begingroup\$ @JackCreasey Yes, the university that I'm studying at wants that we build our own. \$\endgroup\$ – KlaasP Dec 19 '16 at 19:46
  • \$\begingroup\$ or some reactive load with 2.5Ohm ESR? the RPM seems rather low , should there be a high f bridge? or does it have a high pole count? \$\endgroup\$ – Sunnyskyguy EE75 Mar 13 '18 at 22:22
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I think this is all you need to know.

If you are using a Y output generator (rare) then you'd select individual Diodes.

If you are using a Delta generator (most common) then you could specify a block type 3 phase rectifier such as this. Notice here that the maximum DC current is specified for 120deg conduction angle per diode pair.
When it comes to 3 phase rectifiers you will also notice that there is a tendency to use high voltage avalanche diodes, so it's often cheaper to get 1000 - 1200 V devices than it is for 200 -300 V devices at any given current rating.

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You need a three-phase, full-wave bridge rectifier similar to the one in the DB-25 box pictured in the Swea converter literature. It appears to be just a 25-amp rectifier module with three input terminals and two output terminals. It is bolted to the metal housing of the box for heat dissipation purposes. It is probably rated at least 200 volts, peak inverse voltage.

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200 Volt diodes will be fine. The nominal output volts is only 50 V. Normal Si diodes will waste say 1.1 V at say 20 Amp. This is a significant percentage of your paltry 1KW. Remember the bridge has 2 series conducting paths so 2.2 volts are gone. In other words 4.4% power wasted. Shottky diodes could be used which waste about half the volts so your losses could be 2.2%. This is easy but you could do better still with a synchronous rectification scheme using low on-resistance MOSFETs which will cost more.

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