Three-Phase Full-Wave Rectifier question

Discussion in 'General Electronics Chat' started by BrainFog, Mar 5, 2011.

  1. BrainFog

    Thread Starter Member

    Jan 24, 2011
    I am still learning electronics so take this into account when you reply, for example when using acronyms could you put in brackets what they stand for. Thanks

    I have been randomly looking online for information about power supplies. One interesting way of achieving stable DC (Direct Current) current from AC (Alternating Current) from the mains socket, 240v 50Hz, seems to be by using Three-Phase Full-Wave Rectification. I have easily found many schematics showing how to turn a 3 phase AC source into a stable DC current but nothing pertaining to how I get that 3 phase AC source.

    I remember reading a few weeks ago about how inductors and capacitors can cause slight changes in the phases of AC. Is this how it is done?

  2. Adjuster

    Well-Known Member

    Dec 26, 2010
    The 3-phase rectifier is very useful if you already have three-phase AC, but if you only have a single-phase supply this is not the best approach. Generating a 3-phase supply from the single-phase supply would require costly equipment and would waste some energy. It is more efficient to use full-wave rectification of the single-phase supply.

    It is actually quite difficult to derive a good three-phase supply from single-phase, and even today rotary motor generator sets are sometimes used. Passive phase-shift circuits are possible in principle, but it is pretty much impractical to obtain a correctly balanced 3-phase supply, independent of loading. It is possible to operate 3-phase motors - after a fashion - from single phase using a passive starting system, but that is not the same thing.

    A more modern approach would involve a three-phase inverter, probably supplied by obtaining DC from the single-phase input in the first place.