ABSTRACT
This paper presents a novel bidirectional
current-fed push-pull DC-DC converter topology with galvanic isolation. The
control algorithm proposed enables full-soft-switching of all transistors in a
wide range of input voltage and power with no requirement for snubbers or resonant
switching. The converter features an active voltage doubler rectifier
controlled by the switching sequence synchronous to that of the input-side switches.
As a result, full-soft-switching operation at a fixed switching frequency is
achieved. Operation principle for the energy transfer in both directions is
described, followed by verification with a 300 W experimental prototype. The
converter has considerably higher voltage step-up performance than traditional
current-fed converters Experimental results obtained are in good agreement with
the theoretical steady-state analysis.
KEYWORDS
1.
Current-fed dc-dc converter
2.
Bidirectional converter
3.
Soft-switching
4.
ZVS
5.
ZCS
6.
Push-pull converter
7.
Switching control method
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM
Fig.
1. Full-soft-switching CF push-pull converter proposed.
SIMULATION RESULTS
Fig.
2. Simulation current and voltage waveforms of the switch S1.1.
Fig.
3. Simulation current and voltage waveforms of the switch S1.2.
Fig.
4. Simulation current and voltage waveforms of the switch S4.
CONCLUSION
A
novel bidirectional current-fed push-pull converter with galvanic isolation was
introduced. It features full-softswitching operation of all semiconductor
components, while its DC voltage gain is higher than in traditional current-fed
converters due to the utilization of the circulating energy for the input
voltage step-up. As a result, it does not suffer from short intervals of energy
transfer from the input side to the output side since at least half of the
switching period is dedicated for this. Moreover, it does not require any
clamping circuits, since the novel control algorithm features natural clamping
of the switches at the current-fed side. Despite a relatively high number of
semiconductor components, it shows the peak efficiency of 96.3%, which does not
depend on the energy transfer direction for the corresponding operating point. Soft-switching
operation with continuous current at the currentfed side makes the converter proposed
suitable for residential battery energy storage systems. Further research will
be directed towards experimental verification of the converter performance with
a lithium iron phosphate battery.
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