ABSTRACT
In this paper, by investigating the topology
derivation principle of the phase shift controlled three-level DC/DC converters,
the modular multilevel DC/DC converters, by integrating the full-bridge
converters and three-level flying-capacitor circuit, are proposed for the high
step-down and high power DC-based systems. The high switch voltage stress in the
primary side is effectively reduced by the full-bridge modules in series.
Therefore, the low-voltage rated power devices can be employed to obtain the
benefits of low conduction losses. More importantly, the voltage auto-balance
ability among the cascaded modules is achieved by the inherent flying
capacitor, which removes the additional possible active components or control loops.
In additional, zero-voltage-switching (ZVS) performance for all the active
switches can be provided due to the phase shift control scheme, which can
reduce the switching losses. The circuit operation and converter performance
are analyzed in detail. Finally, the performance of the presented converter is
verified by the simulation results.
KEYWORDS
1.
Modular
multilevel DC/DC converter
2.
Phase shift
control scheme
3.
Input voltage
auto-balance
4.
Zero voltage switching
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.1. Proposed modular multilevel DC/DC converter with input voltage auto-balance
ability.
SIMULATION RESULTS
Fig.2.
Simulation waveforms: (a) Input voltage without flying capacitor and (b) Input
voltage with flying capacitor.
Fig.3. Simulation result of primary voltage and current.
Fig.4. Simulation
result of ZVS operation: (a)ZVS operation for S11 and (b) ZVS operation
for S14.
Fig.5. Simulation result of
input voltage sharing.
CONCLUSION
In this paper, a novel phase shift controlled modular multilevel
DC/DC converter is proposed and analyzed for the high input voltage DC-based
systems. Due to the inherent flying capacitor, which connects the input divided
capacitors alternatively, the input voltage is automatically shared and balanced
without any additional power components and control loops. Consequently, the
switch voltage stress is reduced and the circuit reliability is enhanced. By
adopting the phase shift control scheme, ZVS soft switching performance is
ensured to reduce the switching losses. The modular multilevel DC/DC converter
concept can be easily extend to N-stage converter with stacked
full-bridge modules to satisfy extremely high voltage applications with low
voltage rated power switches.
REFERENCES
[1]
H. Kakigano, Y. Miura and T.
Ise, “Low-Voltage Bipolar-Type DC Microgrid for Super High Quality
Distribution,” IEEE Trans. Power Electron., Vol. 25, No. 12, pp.
3066-3075, Dec 2010.
[2]
S. Anand and B. G.
Fernandes, “Reduced-Order Model and Stability Analysis of Low-Voltage DC
Microgrid,” IEEE Trans. Ind. Electron., vol. 60, No. 11, pp. 5040-5049,
Nov 2013.
[3]
S. Anand and B. G.
Fernandes, “Optimal voltage level for DC microgrids,” IEEE Conf. Ind.
Electron. (IECON), pp. 3034-3039, 2010.
[4]
D. Salomonsson, L. Soder and
A. Sannino, “An Adaptive Control System for a DC Microgrid for Data Centers,” IEEE
Trans. Ind. Appl., vol. 44, No. 6, pp. 1910-1917, Nov./Dec. 2008.
[5]
K. B. Park, G. W. Moon and
M. J. Youn, “Series-Input Series-Rectifier Interleaved Forward Converter With a
Common Transformer Reset Circuit for High-Input-Voltage Applications,” IEEE
Trans. Power Electron., vol. 26, No. 11, pp. 3242-3253, Nov 2011.
