Download optimized operation of current-fed dual active bridge dc

OPTIMIZED OPERATION OF CURRENT-FED DUAL ACTIVE BRIDGE DC-DC
CONVERTER FOR PV APPLICATIONS
ABSTRACT:
The current-fed dual active bridge (CF-DAB) dc-dc converter gains growing applications
in photovoltaic (PV) and energy storage systems due to the advantages of wide input voltage
range, high step-up ratio, low input current ripple and multiport interface capability. In addition,
the direct input current controllability and extra control freedom of CF-DAB converter make it
possible to buffer the double-line-frequency energy in grid-interactive PV systems without using
electrolytic capacitors in the dc-link. Therefore, the PV system achieves high reliability as well
as high efficient maximum power point tracking. This paper studies the optimized operation of
CF-DAB converter for PV application in order to improve the system efficiency. The operating
principle and soft-switching conditions over the wide operating range are thoroughly analyzed
with phase shift and duty cycle control, and an optimized operating mode is proposed to achieve
minimum root-mean-square (rms) transformer current. The proposed operating mode can extend
the soft-switching region and reduce the power loss, especially under heavy load and high input
voltage. And the efficiency can be further improved with higher dc-link voltage. A 5 kW
hardware prototype was built in the lab, and experimental results are provided for verification.
The paper provides a design guideline for CF-DAB converter applied to PV systems, as well as
other applications with wide
input voltage variation
INTRODUCTION:
In addition, the direct input current controllability and extra control freedom of CF-DAB
converter make it possible to buffer the double-line-frequency energy in grid-interactive PV
systems without using electrolytic capacitors in the dc-link.
Therefore, the PV system achieves high reliability as well as high efficient maximum power
point tracking. This paper studies the optimized operation of CF-DAB converter for PV
application in order to improve the system efficiency.
The operating principle and soft-switching conditions over the wide operating range are
thoroughly analyzed with phase shift and duty cycle control, and an optimized operating mode is
proposed to achieve minimum root-mean-square (rms) transformer current.
The proposed operating mode can extend the soft-switching region and reduce the power loss,
especially under heavy load and high input voltage. And the efficiency can be further improved
with higher dc-link voltage
EXISTING SYSTEM:
DAB converter is a preferred option, as it has a small component count, offers isolation,
and allows for high power operation. In addition, it has the ability to accommodate a wide range
of voltage levels, as it may be controlled to operate in buck or boost modes
PROPOSED SYSTEM:
This paper proposes an optimized operating mode for CF-DAB converter in PV
application, which minimizes transformer rms current and extends the soft switching operating
range. The operating mode extends the ZVS range and gives less power loss, especially under
heavy load and high input voltage. The front-end CF-DAB dc-dc converter provides galvanic
isolation and boots the PV voltage to a suitable level, so that both dc-dc converter and inverter
can operates efficiently
ADVANTAGES:

Wide input voltage range, high step-up ratio, low input current ripple and multiport
interface
BLOCK DIAGRAM:
TOOLS AND SOFTWARE USED:

MPLAB – microcontroller programming.

ORCAD – circuit layout.

MATLAB/Simulink – Simulation
APPLICATIONS:

PV applications
CONCLUSION:
In this paper, a CF-DAB converter for PV application is proposed. A thorough study for
CF-DAB converters over the whole operating range employing duty cycle plus phase-shift
control is presented. To achieve high efficiency over the wide input voltage range, an optimized
operating mode generating low power loss is developed with selected (D, ϕ). Operating loci with
minimum rms current of transformer for different operating conditions are derived, as well as
soft-switching conditions. The analysis and experimental results verifies that this operating mode
can extend the ZVS range and achieve lower conducting loss compared to “d = 1” mode,
especially for high input voltage; and the efficiency can be further improved by choosing higher
variable dc-link voltage corresponding to input voltage. Since CF-DAB converters can be
extended to multi-terminal applications, this research provides a foundation to study the
optimized operation for those topologies.
.
REFERENCES:
[1] R. W. De Donker , D. M. Divan and M. H. Kheraluwala, “A three-phase soft-switched high
power density dc/dc converter for high power applications,” IEEE Trans. Ind. Appl., vol. 27, no.
1, pp.63 -73, Jan./Feb. 1991.
[2] F. Krismer and J. W. Kolar, “Accurate power loss model derivation of ahigh-current dual
active bridge converter for an automotive application,” IEEE Trans. Ind. Electron., vol. 57, no. 3,
pp. 881–891, Mar. 2010.
[3] F. Krismer and J. W. Kolar, “Efficiency-optimized high current dual active bridge converter
for automotive applications,” IEEE Trans. Ind. Electron., vol. 59, no. 7, pp.2745 -2760, Jul.
2012.
[4] R. T. Naayagi , A. J. Forsyth and R. Shuttleworth, “High-power bidirectional dc–dc converter
for aerospace applications,” IEEE Trans. Power Electron., vol. 27, no. 11, pp. 4366-4379, Nov.
2012.