INTRODUCTION
Due to the scarcity of the improvement of environmental awareness and
fossil fuel energy, the renewable energy has drawn more
attention1,2. Photovoltaic (PV) and wind power play a
crucial role in industrial applications, reducing the
pollution3. However, climate and weather patterns can
cause renewable energy sources to produce inconsistent and intermittent
output voltage 4. Buck-boost converter can regulate
the voltage, which is suitable for renewable energy
conversion5.
The typical buck-boost converter can achieve wide range of input voltage
with simple structure, which has been researched in recent
years6,7. However, its applications are limited by
voltage gain and non-common ground8,9. To achieve
these issues, the CUK, ZETA and SEPIC converter basic on buck-boost
converter are proposed. However, the semiconductors are withstand high
voltage stress and current stress 10.
To improve the above shortcomings, some transformerless single switch
buck-boost converters are proposed. In Banaei and
Bonab11, a ZETA converter based buck-boost circuit is
presented to achieve higher
voltage gain than traditional buck-boost converter. However, the
improvement of voltage gain is limited. Converters in Gorji, et
al.12 and Shu, et al.13 propose the
quadratic voltage gain buck-boost converter that effectively increase
the voltage with the narrow range of duty cycle. But the above quadratic
buck-boost converters have disadvantage of high input current ripple. To
achieve continuous input current and decrease the input ripple, the
inductor is joined straightforwardly to the input source.14,15. Combing the quadratic cell and continues input
current technology, converter in Zhang, et al.16 and
Kumar and Krishnasamy17 are proposed to obtain high
voltage gain only by adjusting the duty cycle. Coupled inductor is
another technology which has been used widely in converter to improve
the voltage gain by regulating the turns ratio. Considering the leakage
inductor of coupled inductor, the passive clamp circuit can be employed
to recycle the energy of leakage inductor and suppress the voltage spike
of power switch18,19. Rong, et al.20proposes a passive clamp circuit-based buck-boost-Cuk converter that
employs a coupled inductor to achieve higher voltage gain. But it is a
non-common ground structure which increases the difficulty of control
system and electromagnetic interference (EMI). In Alizadeh, et
al.21, a single switch quadratic buck-boost converter
based on coupled inductor is presented, which has the benefits of common
ground and continuous input current. Also, it has the disadvantage that
the voltage stress of the power switch is high.
To decrease the voltage stress and current stress on the semiconductor,
dual switches structure is widely utilizing in power electronics
converter22,23. Some dual switches buck-boost
converters are proposed in the recent time. Combing continuous input and
quadratic, a dual switches converter is proposed24. To
further decrease the voltage stress of the power switches, a family of
cascading of boost and ZETA structure converters are proposed in
Veerachary and Khuntia25. Compared with the above
relevant dual switches converter, converter in Okati, et
al.26 has higher conversion ratio. To solve the effect
of non-common and hold on the voltage gain with previous converter, a
modified SEPIC converter is proposed in Wang, et
al.27. A novel negative output buck-boost converter in
Ding and Wang28 and a converter with interleaving two
CUK converters in Taghizadegan Kalantari, et al.29 are
proposed, which achieve wider conversion ratio than above dual switches
converter and have non-common ground structure. Converter in
Hosseinpour, et al.30 proposes a dual switches
converter with common ground structure. The circuit achieves high
voltage gain while minimizing the voltage stress of the switch through
increment passive components’ number, which make the converter bulky.
Considering the above technology, this article proposes a dual switches
buck-boost converter based on coupled inductor. Applying coupled
inductor, high voltage gain can be attained by regulating both the duty
cycle and the turns ratio. The quadratic- like voltage gain is achieved
to wide conversion ratio. Moreover, the voltage stress and current
stress are lower than traditional quadratic cell. The passive clamp
circuit effectively suppresses voltage spike of the power switches, also
recycling the energy of leakage inductor. Common ground between input
sources and load reduces the EMI and difficulty of the control design.
Therefore, the proposed converter can attain output voltage with
stability and suitability for solving the issues of renewable energy
applications.
In this paper, Section 2 analyzes the operation principles. The
stead-state analysis, which includes the voltage gain and stresses of
components, is discussed in Section 3. The component parameter design
and power loss analysis for the proposed converter are discussed in
Section 4 and Section 5, respectively. Section 6 is a comparison of the
characteristics of the relevant converters which can demonstrate the
superior of the presented converter. Section 7 demonstrates the
experiment results with open loop and close loop in both step-up and
step-down modes.