Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Assistance in selecting a right core from different Manufacturers

Status
Not open for further replies.

Bjtpower

Full Member level 5
Joined
Dec 24, 2015
Messages
297
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,298
Activity points
3,893
Core (Inductor) selection for PFC

Dear Friends

Here i am designing a PFC for my application
Design Inputs are
Vin(Min)=200vac
Vin(Max)=265 vac
Output power:400 Watts
Frequency of Converter : 100KHZ

Inductor Ripple Factor:10%

i have calculated some values
Dmin:0.31,Dmax:0.49
I avg (Low voltage):2.45 Amp
Iavg(High Voltage):1.81 Amp

i have used the Formula to calculate the Inductance at high Voltage
L=(Voltage across Inductor) x D(min) x time/(inductor Ripple)
L=(264 X 0.31 X 10X10^-6)/0.38=2.145 mH

Worst case current at low voltage:Imax+(10%of inductor ripple/2)=2.45+0.12=2.57 Amp

Now,
LI^2=2.14 (mH) X (2.57^2)=14.13

now, i have to search the core in TDK/EPCOS (not in Magnetics) i know magnetics approch but it is too costly and samples is not possible easily.

How to go, Pls help me step by step process to select the core

Thanks
Marx
 

Dear Friends

i am getting confused wile selecting a right core from the available Manufacturers.

i am having a book of "CALONEL MACLYMAN" on dc-dc converter with design Example.

i ended up with the design Results in terms of Transformers and inductors but i am only getting the Old cores of Magnetics only.

i dont have classification of other manufacturers vs Magnetics in india.

i want to prove design with the Epcos OR Mahindra Hinoday or Cosmo ferrite Cores.

At the end of discussion, I am in confusion for the Material selection, gap cores and all.

Kindly help me the approch for the Core selections.

Regards
Marx
 

I guess "Magnetics" refers to powder cores. They can be considered as cores with built-in gap, so alternative ferrite cores will usually need a gap, at least if they work in an inductor or flyback transformer.

Parameters aren't really comparable, powder cores have larger saturation flux, but also higher losses, it's probably easiest to start the core design anew, using a manufacturer design tool like the Epcos/TDK MDT software.
 

Yes, i was using the same TDK MDT Software..

but some fields dont know how to fill up..??

Can you help me with the #POST1 Designs

- - - Updated - - -

Also.


I need a some basic Fundamentals of Magnetics in Broad Ways.

Any good articles which can be helpfull to understand the All basics of Magnetics
 

Guys,

Any approach on the selecting a right core..??

I have struggled on the calculating just a Inductance and LI^2..??

are anyone is having hints on the same.. How to proceed..??
 

You have to follow an iterative approach. Basically you need an inductor with current capacity of 2.5A and inductance of 2.2mH.

Step 1: select a random size for the core. Use the manufacturer supplied mu as a guide.

Step 2: select the wire size that is suitable for 2.5A

Step 3: Compute the number of turns and see whether that can fit in the selected core. If not, go over one bigger size. If the window is large, use a smaller size.

Step 4: Select some convenient software for the calculations. They are not difficult but it is possible to make mistakes easily.
 

Micrometals provide a range of free software for selecting their various powdered iron products.

I have used it often to design suitable dc chokes, but they also provide other software packages for more obscure purposes, and one specifically for the design of PFC inductors, which is a very highly specialised application.

I have never tried their PFC software, so cannot comment, but if it is as good as their other magnetics design software it should be a great help.

**broken link removed**
 

You have to follow an iterative approach. Basically you need an inductor with current capacity of 2.5A and inductance of 2.2mH.

Step 1: select a random size for the core. Use the manufacturer supplied mu as a guide.

Step 2: select the wire size that is suitable for 2.5A

Step 3: Compute the number of turns and see whether that can fit in the selected core. If not, go over one bigger size. If the window is large, use a smaller size.

Step 4: Select some convenient software for the calculations. They are not difficult but it is possible to make mistakes easily.

C_Mitra: Thank you..!!
I am unable to understand the "mu" relations

where, mu can be used in the calculation or further..??

i understand that With the help of AL Value, i can calculate the number of turns by using the Formula L=(AL/N^2)
but dont know how it can fit the number of turns in the selected core..??

Its like a random approach i think.
 

Guys..

From reading, i have an some approch.
1) I was reading through Magnetics Catalogue,where they have mentioned that once you know the Inducatnce and inductor current.
2) Then you are able to find the LI^2(mH-A^2)
3) By using the Graphs,LI^2 VS cores suggested-> you will get the Exact core which is necessary for you design.

Now, come to the Point, they have given only for the Kool mu cores,not for the ferrite and others.

also ihave been cross checked it in the ferrites but it is having very high al Value which leads to change my calculations.

Now anyone can help me with the same for how to choose the core..??
 

The biggest problem seems to be calculating core loss, because of the fantastic complexity of the waveform, where both voltage and current amplitudes are constantly changing throughout each half cycle.

Unless you use gapped ferrite, core loss, and core heating will usually be the limiting factor for other materials. Also, the change in permeability of the core with dc can really complicate things.

That is why simulation software is probably about the only realistic way to get started with PFC magnetics design. The software is usually smart enough to give figures for winding fill factor, temperature rise, and relative cost of various core sizes and materials.
 

also ihave been cross checked it in the ferrites but it is having very high al Value which leads to change my calculations.
Please review my comment in post #3. Inductors without air gap aren't feasible, you won't use the "high Al value" as is if you make an inductor. At the end of the day, core form factors will be similar for distributed (powder core) or discrete (ferrite) air gap.

It's basically possible to compile a table of I²L numbers per core size, as it's published for the Magnetics powder cores. Ferrite core manufacturers had tables of transmitted power for different cores and inverter topologies versus core size. If you ask a manufacturer of inductive components for a transformer or inductor quotation, he probably has his own tables or software tools.

Unfortunately I can't answer your question with a simple formula or a link. I would perform the same iterative approach you are describing.
 

Now, come to the Point, they have given only for the Kool mu cores,not for the ferrite and others... ...

If you do not have the exact data for the core you have, just use some conservative number: say 400 or 500 (for mu). It is very unlikely to be less than that.

I suggest you use some software provided by some of the companies; that way chances of making mistakes will be far less.
 

400 w is rather typical power level. try to find ref design for PFC with similar power and analize cores used.
for example, my colleague have designed 400W (90-265 AC input, FOT mode) pfc with E42/21/20 ferrite core
 

E42 code may perhaps be bigger than needed at 100 kHz; but then overrating the size is a good move. But I do not understand what is FOT mode.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top