ABSTRACT
This paper proposes a novel isolated
high step-up converter for sustainable energy applications. Through an
adjustable voltage-multiplier module, the proposed converter achieves a high
step-up gain without utilizing either a large duty ratio or a high turns ratio.
The voltage-multiplier modules are composed of coupled inductors and switched
capacitors. Due to the passive lossless clamped performance, leakage energy is
recycled, which alleviates a large voltage spike across the main switches and
improves efficiency. Thus, power switches with low levels of voltage stress can
be adopted for reducing conduction losses. In addition, the isolated topology
of the proposed converter satisfies electrical-isolation and safety
regulations. The proposed converter also possesses continuous and smooth input
current, which decreases the conduction losses, lengthens life time of the
input source, and constrains conducted electromagnetic-interference problems.
Finally, a prototype circuit with 40 V input voltage, 380 V output, and 500 W
maximum output power is operated to verify its performance. The maximum
efficiency is 94.71 % at 200 W, and the full-load efficiency is 90.67 % at 500
W.
KEYWORDS
1.
High Step-Up
2.
Voltage-Multiplier
Module
3.
Isolated
Converter
SOFTWARE:
MATLAB/SIMULINK
BLOCK
DIAGRAM:
Fig. 1. Block diagram of a typically sustainable energy system.
Fig.
2. Proposed isolated high step-up converter for sustainable energy
applications.
EXPERIMENTAL RESULTS:
(a) Measured waveforms of vDS1, vDS2,
iLin and
iLk
(b)
Measured waveforms of vDc, vDr and iDr
(C)Measured
waveforms of vDf1, vDf2, iDf1 and iDf2
(d)
Measured waveforms of vDo, iDo and Vo
Fig.3 The
experimental waveforms measured at a full load of 500 W.
CONCLUSION
This
paper has presented the theoretical analysis of steady-state and experimental
results for the proposed converter, which successfully demonstrates its
performance. A prototype isolated converter has been successfully implemented
with a high step-up ratio and high efficiency for sustainable energy
applications. The presented circuit topology inherently makes the input current
continuous and smooth, which decreases the conduction losses, lengthens the
life time of the input source, and constrains conducted EMI problems. In
addition, the lossless passive clamp function recycles the leakage energy and
constrains/lowers the voltage spikes across the power switches. Meanwhile, the
voltage stress on the power switch is restricted and is much lower than the output
voltage Vo,
which is 380 V. Furthermore, the full-load efficiency is 90.67% at Po =500
W, and the maximum efficiency is 94.71% at Po = 200 W. Thus, the proposed
converter is suitable for renewable-energy applications that need high step-up
conversion and have electrical-isolation requirements.
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