A Single-Switch Converter with High Step-up
Gain and Low Diode Voltage Stress Suitable for
Green Power-Source Conversion
This paper proposes a single-switch converter with high step-up gain and low
diode voltage stress, suitable for green power-source conversion. By employing a
coupled inductor and switched capacitor, the proposed converters achieve high
step-up conversion ratio without adopting extremely high duty ratio or high turns
ratio. The voltage spike that occurs on the power switch is alleviated, which allows
a low-voltage-rated power switch with low RDS(ON) to be adopted, thus reducing
the conduction losses. Because the energy of the leakage inductor is recycled, the
efficiency is improved. In addition, all diodes’ voltage stresses are lowered and are
the same, so the selection of power diodes is convenient. Finally, a 300 W
prototype circuit with an input voltage of 24 V and an output voltage of 400 V is
implemented to verify the performance and functionality of the presented
converter. Moreover, the measured highest efficiency is 95.4%.
In an effort to reduce carbon emissions and provide for environmental protections,
sustainable and renewable energy (so-called green power sources) are receiving
increasing attention and playing important roles toward achieving energy savings
and overcoming the issue of energy shortage. Green power sources normally
include renewable energy sources, such as photovoltaic (PV) panels and fuel
cell stacks, and backup sources, such as a battery set. The voltage levels of these
green power sources are low (typically12~48 V); thus, high step-up DC/DC
converters are required and have been widely utilized in green power supplies.
Some high step-up converters that utilize coupled inductors and switched
capacitors, which recycle the leakage-inductance energy, lower the voltage
stresses, and obtain high efficiency, have been proposed.
This paper proposes a novel single-switch converter with high step-up
voltage gain and low diode voltage stress, suitable for green power-source
conversion. The proposed converter utilizes coupled inductor and switched
capacitor for achieving high step-up conversion.
The coupled inductor functions as a voltage multiplier and the switched
capacitor supplies the circuit with extra voltage gain. In addition, the
proposed converter performs as a forward converter with boosting capacitors
to lift the voltages of switches capacitors, and performs as a boost-fly back
converter with switched capacitor to provide high-voltage sources to the
The converter easily achieves high step-up voltage gain.
Due to the passive lossless clamped performance, leakage energy is recycled
to the output terminal. Hence, the large voltage spike across the main switch
is alleviated and the efficiency is improved.
The voltage stress on the switch is substantially low; thus a low-voltagerated power switch with low RDS(ON) can be adopted.
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