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288 F. L. Luo and H. Ye
inductance L is small, and load current is high. The condition
for DCM is
M
Q
≤
2kz
N
(14.124)
The output voltages in DCM are
V
O
= V
O+
=|V
O−
|=
4 +k
2
(1 −k)
z
N
2
V
I
with
2kz
N
≥
4
1 −k
(14.125)
Summary for all D/O Luo-converters:
M =
V
O+
V
I
=
|V
O−
|
V
I
; L =
L
1
L
2
L
1
+L
2
; L = L
11
; R = R
1
;
z
N +
=
R
fL
; z
N −
=
R
1
fL
11
so that
z
N
= z
N +
= z
N −
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
(14.126)
The variation ratio of the output voltage v
O+
in CCM is
ε
+j
=
v
O+
/2
V
O+
=
k
128
1
f
3
L
2
C
O
C
2
R
(14.127)
The variation ratio of the output voltage v
O−
in CCM is
ε
−j
=
v
O−
/2
V
O−
=
k
128
1
f
3
C
11
C
10
L
12
R
1
(14.128)
The condition for DCM is
k
[1+h(j)]
M
2
j
j + h(j)
2
z
N
≥ 1 (14.129)
The output voltage in DCM is
V
O−j
=
j + k
[2−h(j)]
1 −k
2
z
N
V
I
(14.130)
where
h(j) =
0 if j ≥ 1
1 if j = 0
is the Hong function.
14.5 Super-lift Luo-converters
Voltage-lift (VL) technique has been successfully applied in
DC/DC converter’s design. However, the output voltage of
all VL converters increases in arithmetic progression stage-
by-stage. Super-lift (SL) technique is more powerful than VL
technique. The output voltage of all SL converters increases in
geometric progression stage-by-stage. All super-lift converters
are outstanding contributions in DC/DC conversion technol-
ogy, and invented by Professor Luo and Dr. Ye in 2000–2003.
There are four series SL Converters introduced in this section:
1. Positive output (P/O) super-lift Luo-converters;
2. Negative output (N/O) super-lift Luo-converters;
3. Positive output (P/O) cascade boost-converter;
4. Negative output (N/O) cascade boost-converter;
14.5.1 P/O Super-lift Luo-converters
There are several sub-series of P/O super-lift Luo-converters:
• Main series;
• Additional series;
• Enhanced series;
• Re-enhanced series;
• Multi-enhanced series.
We only introduce three circuits of main series and addi-
tional series.
P/O SL Luo-converter elementary circuit is shown in
Fig. 14.43a. The equivalent circuits during switch on and
switch off are shown in Figs. 14.43b and c. Its output voltage
and current are
V
O
=
2 −k
1 −k
V
I
and
I
O
=
1 −k
2 −k
I
I
The voltage transfer gain is
M
E
=
V
O
V
I
=
2 −k
1 −k
(14.131)
The variation ratio of the output voltage v
O
is
ε =
v
O
/2
V
O
=
k
2RfC
2
(14.132)
P/O SL Luo-converter re-lift circuit is shown in Fig. 14.44a.
The equivalent circuits during switch on and switch off are