ABSTRACT:
Two high
static gain step-up DC-DC converters based on the modified SEPIC converter are
presented in this paper. The proposed topologies present low switch voltage and
high efficiency for low input voltage and high output voltage applications. The
configurations with magnetic coupling and without magnetic coupling are presented
and analyzed. The magnetic coupling allows the increase of the static gain
maintaining a reduced switch voltage. The theoretical analysis and experimental
results show that both structures are suitable for high static gain applications
as a renewable power sources with low DC output voltage. Two experimental prototypes
were developed with an input voltage equal to 15 V and an output power equal to
100 W. The efficiency at nominal power obtained with the prototype without magnetic
coupling was equal to 91.9% with an output voltage of 150 V. The prototype with
magnetic coupling operating with an output voltage equal to 300 V, presents an
efficiency at nominal power equal to 92.2%.
KEYWORDS:
1. DC-DC power conversion
2.
Voltage multiplier and Solar power
generation.
SOFTWARE:
MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Two-stage AC module structure.
EXPECTED SIMULATION RESULTS:
Fig.2.
Input current (CH4), output voltage (CH3), switch current (CH2) and voltage
(CH1) of the modified SEPIC converter without magnetic coupling (10 A/div, 50
V/div,10 μs/div).
Fig.
3. Switch current (CH2) and voltage (CH1) of the modified SEPIC converter
without magnetic coupling (10 A/div, 50 V/div, 2.5 μs/div).
Fig.4.
L1 (CH4) and L2 (CH2) inductor current of the Modified SEPIC converter without
magnetic coupling (10 A/div, 10 μs/div).
Fig.5.
Output diode Do voltage (CH1) and current (CH4) of the modified SEPIC converter
without magnetic coupling (5 A/div, 50 V/div, 5 μs/div).
Fig.6.
Reverse recovery current of the output diode Do (CH4) and output diode Voltage
(CH1) of the modified SEPIC converter without magnetic coupling (2 A/div, 50
V/div, 100 ns/div).
Fig.7.
Input current (CH4), output voltage (CH3), switch current (CH2) and switch
voltage (CH1) of the Modified SEPIC converter with magnetic coupling and
voltage multiplier (10 A/div, 50 V/div,10 μs/div).
Fig.
8. Switch current (CH2) and switch voltage (CH1) of the Modified SEPIC
converter with magnetic coupling and voltage multiplier (2 A/div, 50 V/div, 1
μs/div).
Fig.
9. L1 (CH3) and L2 (CH4) inductor current of the Modified SEPIC converter with
magnetic coupling (5 A/div, 10 μs/div).
Fig.10.
Output diode Do voltage (CH1) and current (CH2) of the Modified SEPIC converter
with magnetic coupling (2 A/div, 50 V/div, 2.5 μs/div).
Fig.11.
Input current (CH3), output voltage (CH2), switch current (CH4) and switch
voltage (CH1) of the Modified SEPIC converter with magnetic coupling and
voltage multiplier operating with Vi=15 V and Po=50 W (5 A/div, 50 V/div, 5
μs/div).
Fig.12.
Input current (CH3), output voltage (CH2), switch current (CH4) and switch
voltage (CH1) of the Modified SEPIC converter with magnetic coupling and
voltage multiplier operating with Vi=24 V and Po=50 W
(5
A/div, 50 V/div, 5 μs/div).
CONCLUSION:
Two new topologies of non isolated high
static gain converters are presented in this paper. The first topology without
magnetic coupling can operate with a static gain higher than 10 with a reduced
switch voltage. The structure with magnetic coupling can operate with static
gain higher than 20 maintaining low the switch voltage. The efficiency of proposed
converter without magnetic coupling is equal to 91.9% operating with input
voltage equal to 15 V, output voltage equal 150 V and output power equal 100 W.
The efficiency of
proposed converter with magnetic coupling is equal to 92.2% operating with
input voltage equal to 15 V, output voltage equal 300 V and output power equal 100
W. The commutation losses of the proposed converter with magnetic coupling are
reduced due to the presence of the transformer leakage inductance and the secondary
voltage multiplier that operates as a non dissipative clamping circuit to the
output diode voltage.
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