three-phase bridge rectifier

hey everybody
i need a three-phase bridge rectifier 12V for my project
my question is , it would be better if i build my own , or buy one (in this case would you recommend me a good rectifier 12V)
it will supply two other circuits : an electronic circuit (5V and 12V) and a motor starter (12V ??? A)

you can simply build one for your self eccept you need big current..

Do you mean 12V output? I do not think you need three phase rectifier if your output is 12V. I think Single phase is good enough. But you must know current rating as well. My suggestion is you can buy any adaptor that can give 12V output with desired current (A) rating. That can feed 12V to motor. You can use that 12V and regulator (such as 7805) to produce 5V for electronics circuit. Hope that help.

eiphan said:

Do you mean 12V output? I do not think you need three phase rectifier if your output is 12V. I think Single phase is good enough. But you must know current rating as well. My suggestion is you can buy any adaptor that can give 12V output with desired current (A) rating. That can feed 12V to motor. You can use that 12V and regulator (such as 7805) to produce 5V for electronics circuit. Hope that help.

Click to expand...

thank you for your suggestion , but i need a rectifier because i have 12V AC and as you said single phase is good enough

dxtr said:

hey everybody
i need a three-phase bridge rectifier 12V for my project
my question is , it would be better if i build my own , or buy one (in this case would you recommend me a good rectifier 12V)
it will supply two other circuits : an electronic circuit (5V and 12V) and a motor starter (12V ??? A)

Click to expand...

What motor you plan to start with this device (motor starter) ?

Often car engine starters have at least 100A-200A at 12-13V.

You can use strong rectifying diode like for welding devices. They are strong and for higher currents, can be for up to 1000A and more. For you diode for up to 300A will be fine.

If you have transformer with central tap, you can use two diodes, or if you dont have central tap then four in Graetz link.

Also take in mind that diode make voltage drop.


**broken link removed**

If we have 12V at 200A its 2400W or 2,4KW this is under single phase capacity (Single phase max 3,6KW for standard 16A per phase).

Often three phase transformer is used for auto starter device, to reduce impact on house power lines.


Current will depend from car which you want to start with this, usually "normal" family cars have between 100-150A starter, and some SUVs can need luts more current when cranking, as older US cars around 5000cm3 +/- 1000cm3.

Also time for cranking should be limited in secunds, after that device should rest to cooldown if needed, or for longer cranking time use stronger parts, diodes and transformers.

Transformer should have little more voltage then 12V, because diode voltage drop. Thise stronger diodes have higher voltage drop then standard everyday Si rectifier diode 0,7V. This should be incalculated for transformer secundar voltage.

I also saw autotransformer as car engine starter, but better is primar/secundar design.

;-)


For car service, you can spice this device with nice LED voltmeter on device output and LED Thermometer of device transformer coils, and automatic thermal 220V side disconnection as device protection.

If you dont have transformer for this, cheapest way to get it is to search and look for transformer welding device. You can remove few secundar turns from secundar and adjust needed voltage.


My opinion about this is ok, but to make cheaper more useful variant, consider usage of one 100Ah or greater car starter battery, specialy used for this purposes, which is always on standby with float charger. That battery can be on some moving cart with cables, when no needed that battery can be used for alarm or emergency lights.