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=
I
_
_
max
η
in
rms
*
V
The peak current is
I
=
1
2 .
*
I
I
_
_
ocp
pk
r
pk
The actual leakage inductance (
shorted is around 13uH. Therefore, the inductance for the independent resonant choke is:
=
−
=
L
L
L
_
r
choke
r
leak
If a magnetic core with specs of RM10/PC95 is selected, where
to be 0.08T to reduce core loss, the minimum turns can be given as:
⋅
L
_
=
r
choke
N
min
⋅
L
B
A
max
L
2.2.7
Transformer design
From Figure 2, the normalized frequency
=
. 1
28
. Accordingly the actual minimum frequency
G
pk
=
=
*
. 0
35
f
F
f
min
r
The voltage across the primary winding can be calculated as
t =
period is around:
2
+
(
)
n
V
V
=
Δ
o
f
N
A
p
e
2
f
min
The minimum number of turns at primary side can be found:
+
(
)
n
V
V
=
o
f
N
min
Δ
p
2
*
f
A
B
min
e
=
2
161 mm
Where
with PQ3230 core.
A
e
Then
can be calculated as:
N
min
p
16
5 .
( *
=
N
min
3
p
2
*
30
*
10
*
The number of turns at primary side is selected as
calculated accordingly:
Application Note
300
P
=
in
. 0
96
*
151
_
_
min
in
rms
=
=
2
*
I
_
_
r
pk
r
rms
=
. 3
49
A
) measured at primary side with one of the secondary side winding
L
leak
40
uH
−
6
40
*
10
*
. 3
49
I
_
=
r
pk
−
. 0
08
*
90
*
10
min
L
F
=
3
*
85
*
10
30
kHz
1
. According to Faraday's law:
f
min
B
Δ
B
+
12
0
) 1 .
=
33
−
6
161
*
10
*
. 0
62
=
. 2
06
A
.
79
. 2
91
A
. The OCP level is set with about 20% margin:
A
_
e
=
19
4 .
6
=
. 0
35
has been located to achieve maximum gain
min
is:
f
min
=
V
n
p
=
. 0
62
is selected to avoid magnetic saturation.
T
=
33
. The secondary side turns can be
N
min
p
9
=
2
90mm
, and
B
max
min
+
(
)
. The half switching cycle
V
V
o
f
[11]
is selected
[12]
[13]
2011-07-06
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