I'm curious about the variations and their effects in the design of
power supplies intended to utilize three phase AC power to produce DC
output. In particular I am wanting to understand the harmonic effects
of choosing between wiring the phases in parallel vs. series. All the
schematics I have seen on the net show a parallel design. But what
about doing a series design?
By a series design, what I mean is that each of the three phases is wired from separate transformer secondaries with a full wave bridge rectifier, and the DC side of each of those is wired in series.
In the parallel design, it would seem to me that the current waveform would be affected by the fact that different phases are at different voltage, and all the current would flow from just one phase at a time resulting in harmonic currents. A series design could have current in all three phases all the time.
I'm also wondering about the effect of the series voltage on the rectifier switching where the voltage from the other two phases could bias the rectifiers the wrong way, and put reverse current flow on the transformer secondaries (backfeed). Could controlled thyristor designs avoid this? But it would seem to me that even a parallel design could have such issues.
Do you know of any information source that would show a series type design to be workable, or unworkable? The ideal goal would be to have all the continuous power that multiphase AC can provide in the form of DC output with a power factor of 1.0 and no harmonics (however that is formally measured), with reasonable efficiency.
By a series design, what I mean is that each of the three phases is wired from separate transformer secondaries with a full wave bridge rectifier, and the DC side of each of those is wired in series.
In the parallel design, it would seem to me that the current waveform would be affected by the fact that different phases are at different voltage, and all the current would flow from just one phase at a time resulting in harmonic currents. A series design could have current in all three phases all the time.
I'm also wondering about the effect of the series voltage on the rectifier switching where the voltage from the other two phases could bias the rectifiers the wrong way, and put reverse current flow on the transformer secondaries (backfeed). Could controlled thyristor designs avoid this? But it would seem to me that even a parallel design could have such issues.
Do you know of any information source that would show a series type design to be workable, or unworkable? The ideal goal would be to have all the continuous power that multiphase AC can provide in the form of DC output with a power factor of 1.0 and no harmonics (however that is formally measured), with reasonable efficiency.
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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