[SOLVED] Designing Coupled Inductor for high gain boost DC-DC Converter

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sudhinpk

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For my mtech thesis I need to design a coupled inductor for my DC-DC boost converter. There are no details provided in paper except they are using coupled inductor: ETD-59, core pc40, Np : Ns =1 : 4 Lm =48 μH; Lk = 0.25 μH. Can anybody help me with the design?
 


Core EDT59, Material N87 from Epcos
Np = 12Turns,Ns = 1Turn, Air gap = 2mm
 

smijesh said:
Core EDT59, Material N87 from Epcos
Np = 12Turns,Ns = 1Turn, Air gap = 2mm
Click to expand...

Can you provide me design steps? or any resources which I can refer? I am planning to design this circuit for 100 W.
 

For 100W output
Core EDT59, Material N87 from Epcos
Np = 9Turns,Ns = 36Turn, Air gap = 1mm
 
Can you please specify how you chosen 9 turns as primary?
 

AL Value of the core = Inductance/ Turns*Turns

Required air gap is 1mm ,Inductance is 48uH.so the AL value of the core will be 550nH

Number of turns in primary = Sq(Inductance /AL value) = 9 Turns
 
How can we choose inductance value same as mutual inductance value?
 

You can calculate the mutual inductance using below equation
Two inductors whose inductances are given as 75mH and 55mH respectively, are positioned next to each other on a common magnetic core so that 75% (K)of the lines of flux from the first coil are cutting the second coil. Calculate the total mutual inductance(M) that exists between them.
M = K *Sq Root(L1*L2)
M = 0.75* Qq Root(75mH*55mH) =48.2mH
 

Thanks. I asked with respect to my paper. They given Lm = 48uH. Is it mutual inductance? Can you help me to calculate values of L1 and L2 for my topology?
 

sudhinpk said:
Thanks. I asked with respect to my paper. They given Lm = 48uH. Is it mutual inductance? Can you help me to calculate values of L1 and L2 for my topology?
Click to expand...

AL Value = 550nH
L primary = 550nH*9*9 = 44.5 uH
L Secondary = 550nH*36*36 = 713uH
Mutual Inductance
M = 0.75* Qq Root(44.5uH*713uH) =133.6uH
 
How do you got AL Value? Is it from the specifications of the core mentioned in the paper?
 

I got AL value from core datasheet
AL value without air gap = 4170nH Minimum
AL value with 1mm air gap = 550nH 5%
 

Thanks. In my paper Lm=48uH is designed for 400W. Can we select the same for 100 W?
 

For 400W we consider 2mm air gap but for 100W application we considered only 1mm air gap so it will workout.
 
That's really helpful.Thanks.
For my report I need to show calculation steps for Lm value. When I tried it with volt second balance I got different value (34 mH). Do you have any suggestions for it?
 

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