OU/COP>1 switched cap PS cct like Tesla's 'charge siphoning'

[poynt99]

let's get back to the original point:  i commented that there's a discrepancy between the energy efficiency claimed for SMPS operation (>90%) and that claimed by text-books for the fundamental process of getting charge stored in a capacitor (50%)

The comparison is between apples and oranges. I see no descrepancy as each is correct in its own right.

we're told by text-books that external work has to be done to charge a capacitor because, as it charges, the polarisation of the dielectric increases and the applied source has to do work to overcome this increasing opposition

This of course assumes they are referring to the scenario where only a piece of wire or resistor is connecting the source to the capacitor in question. In this case half of the work is lost. This is well known and generally accepted. Caution needs to be exercised in interpreting what the text book is actually saying. Please post the exact quote from the textbook being referred to. It might help clear things up.

the same text-books do not appear to offer exceptions to this inherent behaviour - so IF this WERE a fundamental truth about the work function involved in charging a capacitor then it OUGHT TO apply in whatever circumstances a capacitor gets charged

Again, this comes down to interpreting what the book is saying, and what the intent of their message is. It would also be a very good idea to obtain more than one source for this type of information and compare.

i am not saying that the text-books are correct or incorrect on this - i am pointing out an inconsistency between their explanation of why work needs to be done in charging a capacitor (side effect: 50% efficiency) and our experience of real-world circuits, like some SMPS systems (90+% energy efficiencies), which may involve the frequent repetitive charging of a capacitor

The "why" of the fact that work needs to be done is inherent in that charging is being done through a resistance. If the text book does not state otherwise, this must be assumed and the lesson being conveyed is therefore correct.

IF the text-book justification for work expended in charging a capacitor is INCOMPLETE or INCORRECT then we can expect to be able, with a suitable circuit arrangement, to charge a capacitor with little penalty of energy loss

If the textbook does not give reasons for the energy loss, then I would say it is incomplete. This is why I suggest posting the exact quotes from the book here. I suspect the text book does state where the energy is being lost however at some point, and in this sense would be complete and correct based on the intent of the lesson being conveyed.

IF HOWEVER the text-books are CORRECT and COMPLETE in their statement about cap charging requiring work to be expended, then this is not consistent with the system efficiencies, >50%, we see when we include inductance and rectification or switching into the charge path

our experience does not tie-in with the text-book

Again this comes down to the intent of the message in the text book. Chances are it's a lesson in the basic physics of charging a capacitor, not one in basic SMPS theory. Also, text books are like anythng else that is produced; some are good quality, and some not so good.

my point is that either there is excess energy available or it IS possible to charge a cap without increasing work required - either way, the text-books need to be updated

The "excess energy" theory is unproven and unlikely as I showed in my previous post, and yes it's been shown and proven that it's possible to charge a capacitor in a near lossless manner. If the text book does not mention "inductors" or "constant current charging" in the same lesson regarding the charging of capacitors, then the intention is not to express ways to increase the efficiency of such, and there is no need to correct or update it.

Merry Christmas all!
.99

[poynt99]

A footnote to my post #203 above:

It should be noted that no work is done in the process of transferring the energy of a pre-charged ideal capacitor through an ideal inductor, through to another ideal capacitor. With 0-Ohm wiring of course.

Regards,
.99

[nul-points]

hi Poynt

thanks for sharing your opinions with us all over the last few days, much appreciated

time to let any visitors to the thread who are interested in these matters go 'into the lab' and test them to their own satisfaction

all the best
s.

[NerzhDishual]

@Poynt99

What is you aim?
"Nul-Points" is a very serious, accurate experimenter and also a very polite, nice,
attentive, friendly and patient person.
I'm not so patient!

Are you another 'OU' Luminary Nitpicker?
IMHO, You sound heavily pontificative. Sound you not?
Did you ever make any experiments or just maths and mainstream text books parroting?

Souffrez Monsieur "Je m'la pète grave", que je vous suggérasse, d'aller vous faire empapahouter
chez les Héllènes.

Jean-Yves

[poynt99]

@Poynt99

What is you aim?
"Nul-Points" is a very serious, accurate experimenter and also a very polite, nice,
attentive, friendly and patient person.
I'm not so patient!

Are you another 'OU' Luminary Nitpicker?
IMHO, You sound heavily pontificative. Sound you not?
Did you ever make any experiments or just maths and mainstream text books parroting?

Souffrez Monsieur "Je m'la pète grave", que je vous suggérasse, d'aller vous faire empapahouter
chez les Héllènes.

Jean-Yves

NerzhDishual,

I would suggest that if you take issue with anything I've posted, that you express your concerns through facts, figures and empirical results. Otherwise you're not likely to drag me into any pointless and time-wasting discussions. Let's keep the focus on the facts please. It's been a productive discussion so far, let's try to keep it that way.

Regards,
.99