STMicroelectronics A 200 W ripple-free input current PFC pre-regulator with the L6563S EVL6563S-200ZRC EVL6563S-200ZRC Fiche De Données

Doc ID 17273 Rev 1

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At this point, all the elements needed to outline a step-by-step practical design procedure 
are in place. For the details of steps 2 to 4, please refer to the algorithm described in 

 

.

1.

The case of a conventional inductor is considered. From the circuit design determine 
the required inductance value L

1

, the maximum peak short-circuit current and, 

considering full load conditions, the rms, DC and AC inductor currents, recalling that 
between them the following relationship holds:

In the case of a flyback transformer the winding to consider is the one on the side where the 
ripple current is to be cancelled. For the forward converter the inductor to consider is the 
output filter inductor.

2. 

Assuming that an EE-shaped ferrite core with a slotted bobbin is used, determine the 
maximum flux density and the maximum flux swing the core is operated at. Tentatively 
select a core size and determine the loss limit, both in the winding (P

Cu

) and the core 

(P

Fe

). Calculate the turn number N

1

 of the AC winding in such a way that the desired 

inductance value L

1

 can be obtained without exceeding either the core saturation limits 

or the permitted core losses. Determine the required gap length

3. 

Calculate the conductor size for the AC winding considering that its resistance must be:

To minimize skin and proximity effects, use litz or multi-stranded wire.

4. 

Calculate the conductor size for the DC winding considering that its resistance must be:

As DC current flows through this winding a single wire is used.

5. 

Wind the entire AC winding in one slot and, in the other slot, wind a couple of layers of 
the wire which is used for the DC winding. Temporarily assemble the core set. If the two 
half-cores are not gapped, use a gap value close to that calculated, to make the 
measurements that follow under conditions as close to those of a finished sample as 
possible. Consider also that a small gap amplifies measurement errors

6. 

Using any of the methods described in 

, measure the leakage inductance 

L

Lk

 (referred to the AC winding) obtained in this way and calculate a first-cut value for 

N

2

:

2

DC

2

RMS

AC

I

I

I

−

=

2
AC

Cu

ac

I

P

R

≤

2

DC

Cu

dc

I

P

R

≤