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.