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284 F. L. Luo and H. Ye
Summary for all N/O Luo-converters:
M =
V
O
V
I
=
I
I
I
O
; z
N
=
R
fL
; R =
V
O
I
O
To write common formulas for all circuits parameters, we
define that subscript j = 0 for the elementary circuit, j = 1
for the self-lift circuit, j = 2 for the re-lift circuit, j = 3 for
the triple-lift circuit, j = 4 for the quadruple-lift circuit, and
so on. The voltage transfer gain is
M
j
=
k
h(j)
[j + h(j)]
1 −k
(14.97)
The variation ratio of the output voltage is
ε =
v
O
/2
V
O
=
k
128
1
f
3
CC
O
L
O
R
(14.98)
The condition for discontinuous conduction mode is
k
[1+h(j)]
M
2
j
j + h(j)
2
z
N
≥ 1 (14.99)
The output voltage in discontinuous conduction mode is
V
O−j
=
j + k
[2−h(j)]
1 −k
2
z
N
V
I
(14.100)
where
h(j) =
0 if j ≥ 1
1 if j = 0
is the Hong function.
14.4 Double Output Luo-converters
Double output (D/O) Luo-converters perform the voltage
conversion from positive to positive and negative voltages
simultaneously using the voltage-lift technique. They work in
the first- and third-quadrants with high voltage transfer gain.
There are five circuits introduced in this section:
• D/O Luo-converter elementary circuit;
• D/O Luo-converter self-lift circuit;
• D/O Luo-converter re-lift circuit;
• D/O Luo-converter triple-lift circuit;
• D/O Luo-converter quadruple-lift circuit.
Further lift circuits can be derived from above circuits.
In all D/O Luo-converters, each circuit has two conver-
sion paths – positive conversion path and negative conversion
path. The positive path likes P/O Luo-converters, and the
negative path likes N/O Luo-converters. We define normal-
ized impedance z
N +
=R/fL for positive path, and normalized
impedance z
N −
=R
1
/fL
11
. We usually purposely select R = R
1
and L = L
11
, so that we have z
N
= z
N +
= z
N −
.
D/O Luo-converter elementary circuit is shown in
Fig. 14.7. Its output voltages and currents (absolute values)
are
V
O+
=|V
O−
|=
k
1 −k
V
I
I
O+
=
1 −k
k
I
I+
and
I
O−
=
1 −k
k
I
I−
When k is greater than 0.5, the output voltage can be higher
than the input voltage.
The voltage transfer gain in CCM is
M
E
=
V
O+
V
I
=
|V
O−
|
V
I
=
k
1 −k
(14.101)
The variation ratio of the output voltage v
O+
in CCM is
ε
+
=
v
O+
/2
V
O+
=
k
16M
E
1
f
2
C
O
L
2
(14.102)
The variation ratio of the output voltage v
O−
in CCM is
ε
−
=
v
O−
/2
V
O−
=
k
128
1
f
3
C
11
C
10
L
12
R
1
(14.103)
This converter may work in discontinuous conduction
mode if the frequency f is small, conduction duty k is small,
inductance L is small, and load current is high. The condition
for DCM is
M
E
≤ k
z
N
2
(14.104)
The output voltages in DCM are
V
O
= V
O+
=|V
O−
|=k(1 − k)
z
N
2
V
I
with
z
N
2
≥
1
1 −k
(14.105)