Electronics > Beginners
Applying DC bias on a high voltage rectified ripple 570VAC down to offset zero
andre123:
I am working on a linear power supply with a 3phase input. I wondering if there was a possibility to shift the rectified(ripple) power signal shown below which spans between 560VAC to 505VAC ( 55VAC difference @130 ohm load) down near to the zero so imainge it could span between 0 to 55VAC .
If the voltage above is adjusted, then i imagine the voltage supply will need to go into a power transformer with a ratio of 3:1 then a go through a diode in series(half-wave rectification) then if needed go through a linear regulator for ripple reductiona and voltage regulation within reasonable expectations.
My target is to setup a 12V ~100mA linear power supply from 3 phase(4-wire) 330V(max)/phase 50Hz.
I've tried to use this high pass filter to adjust the bias but
it shifts mostly under zero, several iterations got me no-where.
under very small loads @100K ohm load, i'm getting results above zero around 20VAC, can't get it near that when load increases
Note: I am bound to have galvanic isolation ( Transformer ) in my application.
I would really appreciate if someone would kindly share their thoughts.
SilverSolder:
--- Quote from: andre123 on January 28, 2020, 01:29:22 pm ---"My target is to setup a 12V ~100mA linear power supply from 3 phase(4-wire) 330V(max)/phase 50Hz."
--- End quote ---
But you said the 3 phase could vary from 550V to zero, or did I misunderstand that?
andre123:
--- Quote from: SilverSolder on January 28, 2020, 01:40:18 pm ---
--- Quote from: andre123 on January 28, 2020, 01:29:22 pm ---"My target is to setup a 12V ~100mA linear power supply from 3 phase(4-wire) 330V(max)/phase 50Hz."
--- End quote ---
But you said the 3 phase could vary from 550V to zero, or did I misunderstand that?
--- End quote ---
I meant in that context that a single line is 330VAC , but when all lines are connected+ rectified the output voltage line spans around 550 as shown in the first picture.
Regards
Andre
ELS122:
I am not completely sure of this, but that's not how diodes work. they don't add up the voltage. if 1 phase of the 3 rectified outputs ~400volts 3 of them (if the same voltage) will also output 400volts. but with more current.
SilverSolder:
If all you want is 12V DC at 100mA... why not just connect a regular 1 phase transformer between any two of the phases, and have the usual bridge rectifier + filter cap + regulator on the other side of that transformer?
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