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Design and Simulation of Nonisolated ZVZCS…….
in high-component availability and easy thermal distribution. A specification for a design example in this paper
is given as follows and the chosen circuit topology for the specifications is shown in Fig.4.
Po =220 W, Vo = 105 V, Vi = 12 V, fs= 15 kHz, ∆Iin = 20%, ∆Vo = 3%.
Considering input current ripple ∆I in, input inductor L f is determined by,
Lf = 0.5(1-D).V in / ∆I in . f s = 70µH.
B. Design of f r
Due to the smaller switch turn off current and duty loss, the below-resonance operation is chosen, and
the resonant frequency f r can be obtained from
f r = 1 / 2π√L r C r and
f r = 1 /2D eff.
So, f r ≤ 42 kHz
C. Design of L r and C r
From the resonant frequency f r,
L r = 3 µH &
C r = 4.7 µF.
The improvement of the proposed RPWM method compared to PWM method are summarized as
follows.
1) Due to the reduced operation duty, the rms current ratings of the switches are reduced by 5-15%,
resulting in reduced conduction losses.
2)Due to the resonant operation, the turn-off current of switches are reduced by 25-60% and falling
slopes of the diode current are reduced, resulting in significantly reduced switching losses.
3)The required capacitance of auxiliary capacitor is dramatically reduced to 1/20 th resulting in reduced
volume and cost.
VII.
SIMULATION CIRCUIT
i
+ -
Discrete,
Ts = 5e-006 s
powergui
Vin
+
-
v
Input Current ,Iin
Input Voltage
double
NOT
m
m
D
D
+
-
i
+ -
v
Diode
+
Diode 1
-
v
i
+ -
i
+ -
i
+ i
- + -
Input Filter Inductor
Auxiliary Capacitor
Auxiliary Inductor
+
-
v
+
-
v
OFF-
SHELF
C
A
P
A
C
I
T
O
R
Output Capacitor
i
+ -
Output Current ,Iout
+
-
v
Output Voltage ,Vout
Duty Cycle
Fig(a) Input voltage
www.ijceronline.com ||May ||2013|| Page 6