guys i did the pain staking calculation ................ from the book luka referred me to .......
calculation:-
skin depth = 6.62/ root of frequency = .0.0209cm
wire diameter = 2 X skin depth = 0.209 X 2 = 0.48cm ~ 26SWG.
bare wire diameter Aw = 3.14D^2/4 = 0.00137
I/P power Pin = Po/n = 400/0.95 = 421W
Ipk = pin X 1.414 /Vin(min) = 421 X 1.414 / 90 = 6.61A
Ripple current = 0.2Ipk = 1.323 A
calculation:-
skin depth = 6.62/ root of frequency = .0.0209cm
wire diameter = 2 X skin depth = 0.209 X 2 = 0.48cm ~ 26SWG.
bare wire diameter Aw = 3.14D^2/4 = 0.00137
I/P power Pin = Po/n = 400/0.95 = 421W
Ipk = pin X 1.414 /Vin(min) = 421 X 1.414 / 90 = 6.61A
Ripple current = 0.2Ipk = 1.323 A
max duty cycle Dmax = (Vo - (Vin X 1.414))/Vo = 0.68
Inductance L = (Vin(min) X 1.414)Dmax/ ripple current X frequency = .000685H
energy Required Eng = LIpk^2/2 = 0.0149 (watt-second).
electrical cofficient Ke= 0.145PoBm^2/10000 = .0003625.
core geometry coefficient Kg = (Eng)^2/ Ke X a = 0.615{cm^5}
ok here is a slight problem the Kg value suggets me use a bigger core say ETD49 or so wat happens if I use a smaller core say ETD34.
Inductance L = (Vin(min) X 1.414)Dmax/ ripple current X frequency = .000685H
energy Required Eng = LIpk^2/2 = 0.0149 (watt-second).
electrical cofficient Ke= 0.145PoBm^2/10000 = .0003625.
core geometry coefficient Kg = (Eng)^2/ Ke X a = 0.615{cm^5}
ok here is a slight problem the Kg value suggets me use a bigger core say ETD49 or so wat happens if I use a smaller core say ETD34.
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lets proceed with ETD34 .....................
current density J =2(Eng)(10000)/Bin X Ap X Ku =1233A/cm^2
this also seems very high...........
neways lets proceed.............
Irms = Ipk/1.414 = 4.67A
bare wire area Aw
= 4.67/1233 = .00394 cm^2.
number of strands Sn = Aw/ area of 26SWG wie = 3.07 ~ 3
number of turns = Wa X Ku /Sn X (area of 26SWG wire) = 129.
current density J =2(Eng)(10000)/Bin X Ap X Ku =1233A/cm^2
this also seems very high...........
neways lets proceed.............
Irms = Ipk/1.414 = 4.67A
bare wire area Aw
= 4.67/1233 = .00394 cm^2.number of strands Sn = Aw
/ area of 26SWG wie = 3.07 ~ 3number of turns = Wa X Ku /Sn X (area of 26SWG wire) = 129.
cal Bpk = F[{(0.4 X 3.14 X N X Ipk(10^-4)}/Lg] = 0.468
new resistance per cm = 1345/Sn = 448.33
winding resistance R = (MLT) N 448.33 (10^-6) = 0.315E
copper loss Pcu = Irms^2 X R = 6.86W.
Regulation a = Pcu/Po =1.717%
Ac flux density Bac = 0.02768T
core loss Pfc=0.018W
total loss =Pcu +Pfc = 6.878W
Temperature Rise = Tr = 82.35C
these things dont seem to be in place ...................
tell me if i had some mistakes...........
regards
sekhar
new resistance per cm = 1345/Sn = 448.33
winding resistance R = (MLT) N 448.33 (10^-6) = 0.315E
copper loss Pcu = Irms^2 X R = 6.86W.
Regulation a = Pcu/Po =1.717%
Ac flux density Bac = 0.02768T
core loss Pfc=0.018W
total loss =Pcu +Pfc = 6.878W
Temperature Rise = Tr = 82.35C
these things dont seem to be in place ...................
tell me if i had some mistakes...........
regards
sekhar
...ermh..., I guess you did not mean 0.48cm, but 0.48mm...
Anyway, please note that the skin effect as calculated in your formulas is valid for a single wire in free space only. Practically this calculation does still fit in single layer windings, and more or less in two layer windings. But not for a massive bunch of conductors.
You will need to consider the proximity effect, which is the extended consequence from the skin effect, when going for multiple conductors.
The skin effect only takes into account the self induced effects of one wire.
The proximity effect additionally takes into account the fields which are caused by the other conductors close by. You may search the web for graphs, which indicate Rac/Rdc for typical winding arrangements depending on frequency.
Furtheron you are neglecting the eddy current losses, which are caused in the winding by the fringing field of the core. Sorry, I do not have a practical calculation model on hand, without finite elements.
You can be sure that you will have more losses than your calculation indicates.
What happens if you chose an etd34 instead of etd49?
More losses than with an etd 49, and consequently much more temperature rise than with an etd49.
New calculation of turns:
Forget it.
a) Your wild formula with a mixture of factors and units seems to be intended for pure AC flux situations with pos an neg flux. But your PFC will have only one flux polarity in the core, no sign reversal. ==> Giving you a factor-two-error for the number of turns.
a) Simplified fringing field calculations tend to indicate an accuracy, which is simply not there.
Anyway, please note that the skin effect as calculated in your formulas is valid for a single wire in free space only. Practically this calculation does still fit in single layer windings, and more or less in two layer windings. But not for a massive bunch of conductors.
You will need to consider the proximity effect, which is the extended consequence from the skin effect, when going for multiple conductors.
The skin effect only takes into account the self induced effects of one wire.
The proximity effect additionally takes into account the fields which are caused by the other conductors close by. You may search the web for graphs, which indicate Rac/Rdc for typical winding arrangements depending on frequency.
Furtheron you are neglecting the eddy current losses, which are caused in the winding by the fringing field of the core. Sorry, I do not have a practical calculation model on hand, without finite elements.
You can be sure that you will have more losses than your calculation indicates.
What happens if you chose an etd34 instead of etd49?
More losses than with an etd 49, and consequently much more temperature rise than with an etd49.
New calculation of turns:
Forget it.
a) Your wild formula with a mixture of factors and units seems to be intended for pure AC flux situations with pos an neg flux. But your PFC will have only one flux polarity in the core, no sign reversal. ==> Giving you a factor-two-error for the number of turns.
a) Simplified fringing field calculations tend to indicate an accuracy, which is simply not there.
i know that that things r nt as they should be .......... but with the given amount of knowledge............ that i have i was able to put down this number with the help of luka........
So should i go forward with this design or should i sit back do some more studying.................
regards
sekhar
@choholic
ok lets start the calculation all over again ........................ u tell me wat to do i will give all my input data, and lets see if can get this thing right atleast on paper......... then I will try making it ..............
and thanks again for pointing out my mistakes.................
and here is the schematic for the pfc
regards
sekhar
ok lets start the calculation all over again ........................ u tell me wat to do i will give all my input data, and lets see if can get this thing right atleast on paper......... then I will try making it ..............
and thanks again for pointing out my mistakes.................
and here is the schematic for the pfc
regards
sekhar
...means I a shall design your PFC, explain every step and then debug it for you...
Sorry, I am out of the game.
i just wanted that u to help me ................ nothing that u have to take the entire burden on ur shoulder.............i will do everything just needed guidance.......neways thanks for help
regards
sekhar
Hi Sekhar!
Of course I do not want to kill your DIY spirit.
Originally you contacted me for support on some inductor questions.
In the mean time I understood, that you are going to learn the entire SMPS topic from scratch.
Basically there is nothing wrong with your intension, but I am not able to spend enough time on your project to give you the required support.
One more comment:
I am not aware of your skill set.
You do not need to be a SMPS specialist, but please do not step into DIYing of offline SMPS, without good knowledge and experience in mains voltage appliances and the required survival rules.
Take care
Markus
Of course I do not want to kill your DIY spirit.
Originally you contacted me for support on some inductor questions.
In the mean time I understood, that you are going to learn the entire SMPS topic from scratch.
Basically there is nothing wrong with your intension, but I am not able to spend enough time on your project to give you the required support.
One more comment:
I am not aware of your skill set.
You do not need to be a SMPS specialist, but please do not step into DIYing of offline SMPS, without good knowledge and experience in mains voltage appliances and the required survival rules.
Take care
Markus
hmmm
Circuit optimization with that core wont be an easy task, I saw in commercial SMPS ETD29 at 100KHZ doing ONLY 400W (music).
I think you should spend more time doing some research for best cores for PFC.
Dont forget, Mosfet, Diodes, every thing will affect performance of your PFC.
No idea about your budget for this project.
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