Half Bridge Topology - PF concerm

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mike7877

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Discussion starter · #1 · Jul 5, 2022

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Recently I bought this PSU for a good price ($130CDN). I was told at the store it's good rebrand - I forget which they said, but the 10 year warranty/105 deg C rated capacitors seem good (if it's at 5-10k hours, not 1 lol)
But I see this, "Half Bridge Topology"
And I'm a bit worried
Does this mean it's only using half the wave of the input?
Won't this screw up power factor, effectively doubling the cost of electricity? For billing, 500 watts PF 0.50 is like 1000 watts PF 1.00

 

shilka

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#2 · Jul 5, 2022

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Thats not how that works

https://www.tomshardware.com/reviews/msi-mpg-a750gf-power-supply-review

That MSI unit is by no means bad sure the hold up time is not all that great but thats not the bigest problem in the world unless you live somewhere with unstable power

 

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mike7877

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Discussion starter · #3 · Jul 5, 2022 (Edited)

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shilka said:

Thats not how that works

https://www.tomshardware.com/reviews/msi-mpg-a750gf-power-supply-review

That MSI unit is by no means bad sure the hold up time is not all that great but thats not the bigest problem in the world unless you live somewhere with unstable power

Click to expand...

I'm not sure which part of the review you want me to look at.
I don't know if you noticed, but that's a review of the 750W model. I'm sure it's design is similar to the 850W version (which I have), but are you sure what you're pointing out is valid for both models?

edit: actually, they might be quite different. The review below has PF measured at 0.99 during their "torture test" (80% load with 45 deg C air at the intake), while Tom's Hardware points out power factor as a "con". This measurement also answers my power factor question. Kind of. I'll continue reading the second link I posted, seems like it'll be enlightening - much more so than the "introduction to" suggests lol (I believe it's an introduction for engineering departments of PSU OEMs made by a component manufacturer)

MSI MPG A850GF 850W Power Supply Review - Page 4 of 7 - The FPS Review
An introduction to LLC resonant half-bridge converter (st.com)

To add to what's missing in my OP: it's got the same guts as Enermax Revolution DF 850W

 

Dogzilla07

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#4 · Jul 5, 2022

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@mike7877 There's no "topology" difference between the 750w and 850w, that's just a way to design PSUs, Aris gave a decent review=good unit.

 

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RockThePylon

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#5 · Jul 8, 2022 (Edited)

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This exact question was addressed recently in a GN video. To sum it up - Half vs. Full bridge is only half the the question, and is essentially meaningless information on it's own.

Also, as far as I know, residential meters can only measure real power, so a poor power factor doesn't affect your billing.

Skip to 9:40 if the link doesn't do it automatically.

 

NattyKathy

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#6 · Jul 10, 2022 (Edited)

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just clarifying, in case OP missed it, that the "full-bridge" vs "half-bridge" in regards to PC power supply topology refers to the DC->DC section, not the Mains->DC section. The initial AC->DC conversion from mains will invariably use a full-bridge rectifier even in really cheap units AFAIK but there are various methods of inverting the DC into high-frequency AC and rectifying back into DC for the actual voltage conversion/regulation part that involve different waveforms and levels of circuit complexity.