ABSTRACT:
In
this paper; a variable dc link based novel multilevel inverter (MLI) topology
is proposed. This proposed topology comprises two variable dc links and a modified
H-bridge unit. This new single-phase topology offers advantages such as
reduction in count of switches; gate drivers and dc sources while
simultaneously improving the power quality. The proposed topology has been
analyzed for both symmetric and asymmetric modes of operation. A comparative
study of the proposed topology with some recent MLI topologies has been
presented. The comparative study indicates that the proposed topology requires
less number of dc sources; switches and driver circuits as compared to other topologies.
The proposed topology has been simulated for 31- level asymmetric configuration
in MATLAB/SIMULINK environment to verify the proper operation of proposed topology.
Harmonic analysis was also performed for 31-level inverter which showed
significant reduction in the total harmonic distortion (THD) for phase voltage
and current waveforms. The proposed topology is suitable for low voltage applications
such as standalone photovoltaic (PV) systems and hybrid electric vehicles
(HEVs).
KEYWORDS:
1. Multilevel
Inverter
2. Asymmetric
Configuration
3. Variable DC Link
4. Reduced
Device Count
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
In
this paper; a novel MLI topology having two variable dc links and a modified
H-bridge unit has been proposed for low voltage applications. Generalized form of
proposed topology was explained for both symmetric and asymmetric modes of
operation from the perspective of quantitative parameters. Through various
comparisons made between the proposed asymmetric topology and other reduced
device count topologies; it is concluded that the proposed topology requires
less number of dc sources; switches and gate drivers as compared with the other
presented topologies in literature. However total PIV in proposed topology is
found to be slightly higher as compared with the ACHE topology. On the basis of
chosen performance indices; proposed topology is found to be more economical as
compared to their counterparts. Performance of 31-level proposed asymmetric
topology was shown by simulated voltage and current waveforms. Since the
switches T5 and T6 in the modified H-bridge have to withstand the total output
voltage of MLI; these two switches must be of high voltage rating and hence the
proposed topology is best suited for LV applications. The proposed topology
also has a distinctive feature of utilizing asymmetric dc sources in a manner
to maintain nearly even blocking voltage stress across the switches (TJ to T4)
in a modified H-bridge. This feature reduces the number of variety of switches
significantly. Harmonic analysis results showed the significant reduction of harmonics
in voltage and current waveforms. So there is no need of filter circuit to
eliminate harmonics. The proposed topology will be beneficial in LV
applications such as standalone PV systems; hybrid electric vehicles (EVs) etc.
due to its various benefits. In future; hardware implementation of the proposed
topology will be done.
REFERENCES:
[I]
L.M. Tolbert; F-Z. Peng and T.G. HabetIer; "Multilevel converters for
large electric drives," IEEE Trans. Ind. AppL; vol. 35; no. I; pp. 36-44;
Jan.lFeb. 1999.
[2]
J. Rodriguez; S. Bernet; B. Wu; J.O. Pontt and S. Kouro,"Multilevel
voltage-source-converter topologies for industrial medium-voltage drives,"
IEEE Trans. Ind. Electron.; vol. 54; no. 6; pp. 2930-2945;Dec. 2007.
[3]
J. Rodriguez; J.S. Lai and FL Peng; "Multilevel inverters: A survey of
topologies; controls and applications," IEEE Trans. Ind. Electron.; vol.
49; no. 4; pp. 724-738; Aug. 2002.
[4]
I. Colak; E. Kabalci and R. Bayindir; "Review of multilevel voltage source
inverter topologies and control schemes," Energy Converso Manag.; vol. 52;
no. 2; pp. 1114- 1128; 2011.
[5]
M. Malinowski; K. Gopakumar; J. Rodriguez and M.A. Perez; "A survey on
cascaded multilevel inverters," IEEE Trans. Ind. Electron.; vol. 57; no.
7;p p. 2197-2206; July 20I O.
