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PC Power Supply Discussion Troubleshooting and discussion of computer power supplies

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  #11  
Old 10-06-2016
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Quote:
Originally Posted by -The_Mask- View Post
Antec High Current Platinum Pro from Delta?

https://www.techpowerup.com/reviews/...CP-1300/8.html
Does that apply? Aris figures were always better looking than Paul's ones.

https://www.techpowerup.com/reviews/...HX1000i/8.html

https://www.techpowerup.com/reviews/...T2_1600/8.html

P.S.: BTW, it could somehow apply:

http://www.hardocp.com/article/2014/...w_psu_review/7

http://www.hardocp.com/article/2012/...upply_review/7
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Old 10-06-2016
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Originally Posted by McSteel View Post
That being said, you simply can't have high efficiency and transient response robustness without going grossly overboard with the price.
Can you elaborate on this, in brief, please.
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Old 10-06-2016
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the PSU's Primary is what decides most of the transient performance. Secondary filtering (especially total capacity/energy storage) contributes a bit, but with rapidly diminishing returns.

Resonant converter tech is sensitive to sudden changes in loading because they cannot freely adjust the PWM duty cycle (if they're not already operating in the PFM mode); that needs to be done at very specific points (just after the falling edge before zero crossing) in not-too-big increments. If operating in the FM region, the modulating wave's slew rate is limited by the controller's abilities.

If not using LLC or ZVS methods, it's very hard to get above Silver efficiency. Double-forward Primary may be made very resilient to transients, but require an ample reservoir (primary caps' capacitance). The switching frequency needs to be as high as possible, increasing transformer losses and necessitating FETs with high ringing resilience. High Secondary capacitance also introduces additional losses; so it's tough getting to Silver, if at all possible, while staying below 200 mV in the standard ATX transient response tests.

Going fully digital and using full bridge instead of half, using > 100 kHz switching and DAC and DSP capable of at least the same sampling rate and reaction time of one cycle, alongside a large but efficient transformer and perhaps even predictive logic in the PSU's main CPU might make for a high efficiency and transient resilience, but at a significant cost increase.
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  #14  
Old 10-07-2016
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Quote:
Originally Posted by McSteel View Post
the PSU's Primary is what decides most of the transient performance. Secondary filtering (especially total capacity/energy storage) contributes a bit, but with rapidly diminishing returns.
Your knowledge of the subject scares me ....

I've run some tests with regard to this. The results are quite interesting.
The test subject is a Platinum Power, MS Industrial platinum. PSU is crap, and that's why I chose him for this test.
The goal is to see the impact of additional LC filter in the secondary measurement. Primarily the ratio Ripple and Transient response time.
Before the intervention ripple at 50% power is 84mV.
Attachment 2425
Transient voltage drop about 255mV. Transient rec. time is about 1,39ms.
Attachment 2426

Adding capacitors Transient voltage drop is about 150mV. Transient recovery time is about 3,21ms. Ripple is reduced to 48,6mV.
Attachment 2427
Attachment 2428
The conclusion;
The transient response can be optimized for a lower voltage drop or for a faster response. When the load is quickly increased, the output capacitor supplies the load with current until the controller reacts to the change and increases its output current. A larger output capacitor provides this current with a smaller amount of output voltage droop; however, a smaller capacitor increases the bandwidth of the device and provides faster response.
An additional effect is reduced ripple, which would mean that the evaluation the quality of the power supply according to ripple measurements is incomplete if there is no insight into the transient recovery time.
Do you agree?

With the addition of LC filter difference will be even more significant.
Transient voltage drop is about 1.2V,Transient rec. time is then 5,33ms. Ripple is even more reduced to 37mV.Attachment 2429
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Old 10-07-2016
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I know the MS-Industrial from M-San group - one of my former employers used to sell those, both solo and inside PC cases
Basically a variant of SunPro Safety series from 2003, those are very popular in our neighborhood (and sold under several small local "brands").

Anyway, this is exactly what I had in mind when I said rapidly diminishing returns
You can choose to have stable steady-state power delivery or a quick reaction/recovery time. Things get a little bit more complicated with very low ESR caps and large pi-coils and the ensuing resonance with the feedback loop

It's possible to bypass this transient response dampening effect if one runs an isolated (think complete galvanic isolation like with optocouplers) remote sensing circuit with a high sampling rate. This way the secondary filter doesn't "mask" the vdrop and the controller reacts timely and accurately. Even if it overshoots the voltage, the robust filtering will smooth this out, especially if the transient is intensive and lasts longer than the combined cap discharge time.

But who would want to over-engineer a PSU like this, and at what cost for the end user?
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