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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 . enter image description here 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

    1. it shifts mostly under zero, several iterations got me no-where.
    2. under very small loads @100K ohm load, i'm getting results above zero around 20VAC, can't get it near that when load increases.
      enter image description here

Note: I am bound to have galvanic isolation ( Transformer ) in my application.

  • I would really appreciate if someone would kindly share their thoughts.
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  • \$\begingroup\$ That doesn't look like an AC power signal to me. It looks like the ripple left after three phase rectification. \$\endgroup\$ – Andy aka Jan 28 at 8:58
  • \$\begingroup\$ yes, that is correct. Can this signal be still manipulated as i imagine ? ; offset adjusted --> transfer through a transformer with the designated turns ratio --> cleaned with caps ? \$\endgroup\$ – Sultanpepper Jan 28 at 9:04
  • \$\begingroup\$ I expect it can but please make it clear in your question that you wish to use ripple voltage that is AC coupled to a transformer or other suitable converter. Details that relate to the question are best kept in the question. \$\endgroup\$ – Andy aka Jan 28 at 9:11
  • \$\begingroup\$ @Andyaka edited the title and description. Would you have any thoughts on this matter ? \$\endgroup\$ – Sultanpepper Jan 28 at 9:18
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    \$\begingroup\$ I probably wouldn't use a transformer, rather I'd remove the DC content with a capacitor and current limiting resistor and protect that output with a TVS diode and then use a rectifier and buck regulator to get the 12 volts \$\endgroup\$ – Andy aka Jan 28 at 9:22

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