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1. HARMONIC MINIMIZATION OF 31-LEVEL
CASCADED MULTILEVEL INVERTOR TOPOLOGY
WITH REDUCED NUMBER OF SWITCHES
UNDER THE GUIDANCE OF
Mr. SHIBU J V BRIGHT, M.E.,
Assistant Professor
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING,
MARIA COLLEGE OF ENGINEERING AND TECHNOLOGY, ATTOOR
PRESENTED BY,
GINU R NAIR (961521411008)
M.E- Power Systems Engineering
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING,
MARIA COLLEGE OF ENGINEERING AND TECHNOLOGY, ATTOOR

2. ABSTRACT
o In this project, an enhanced step-up 31 level inverter is for
Reduced number of Switches. In the past decade, renewable
energy sources such as photovoltaic (PV)-based systems
have attracted much more attention due to the advantages
such as less environmental impact and improved economic
benefits.
o With the rapid growth of power electronics technology, various
converters topologies have been developed for PV systems.
Among these topologies, multilevel inverters have been
receiving significant interest due to the reduced total harmonic
distortion (THD) and improved quality of output waveform.

3. o As the output voltage level increases, the output harmonic
content of such inverters decreases, allowing the use of
smaller output filters.
o Compared with conventional 31-level inverters, the proposed
topology can realize the multilevel inversion with high step-up
output voltage, simple structure, and reduced number of
power switches.
o The operating principle of the proposed inverter has been
analyzed and the output voltage expression has been
derived. In addition, the comparison with existing topologies
of single-phase 31-level inverters is presented.
o Finally, MATLAB simulation results validate the performance
of the proposed topology.

4. INTRODUCTION
o General inverters are two level converters and they cannot
satisfy high power applications. Multilevel inverters are
preferred to satisfy high power applications.
o Multilevel inverters are used to produce very high voltages
based on the configuration used even from a single DC
voltage source.
o Whenever the no of levels of Multilevel inverters are
increased, Total harmonic distortion (THD) of output voltage is
reduced which is suitable for numerous applications.
o So the filter requirement is reduced when multilevel inverters
are used for applications.

5. LITERATURE REVIEW
Multi-input step-up converters based on the switched-diode-capacitor
voltage accumulator. S. Hou, J. Chen, T. Sun, and X. Bi. A switched-
diode-capacitor voltage accumulator (SDCVA) on conventional boost
converter is used to obtain two different kinds of multi-input step-up
converters with high voltage gains, low component stresses, low ripples,
simple control, and high conversion efficiencies: It is based on the parallel
SDCVA and the other based on the serial SDCVA. In the past decade,
renewable energy sources such as photovoltaic (PV)-based systems have
attracted much more attention due to the advantages such as less
environmental impact and improved economic benefits. With the rapid
growth of power electronics technology, various converters topologies have
been developed for PV systems. Among these topologies, multilevel
inverters have been receiving significant interest due to the reduced total
harmonic distortion (THD) and improved quality of output waveform.

6. Structure of boost DC-link cascaded multilevel inverter for uninterrupted
power supply applications. R. Uthirasamy, U.S. Ragupathy, and V. Kumar
Chinnaiyan, A Single-phase seven-level boost DC-link cascaded multilevel inverter
(BDCLCMLI) is used. It consists of boost converter, DC-link module and H-bridge
inverter. Compared with conventional CMLI and two level H-bridge inverter
configurations, the proposed system results in reduction of voltage stress across the
inverter switches, reduced power switches, In the past decade, renewable energy
sources such as photovoltaic (PV)-based systems have attracted much more
attention due to the advantages such as less environmental impact and improved
economic benefits. With the rapid growth of power electronics technology, various
converters topologies have been developed for PV systems. Among these
topologies, multilevel inverters have been receiving significant interest due to the
reduced total harmonic distortion (THD) and improved quality of output waveform.

7. Newly-Constructed Simplified Single-Phase Multistring Multilevel
Inverter Topology for Distributed Energy Resources. Y.-H. Liao and C.-
M. Lai. A Distributed energy resource (DER)-based single-phase inverter is
usually adopted. The study a novel 31-level multistring inverter topology for
DERs-based dc/ac conversion system is done. In this study, a high step-up
converter is introduced as a front-end stage to improve the conversion
efficiency of conventional boost converters and to stabilize the output dc
voltage of various DERs such as photovoltaic and fuel cell modules for use
with the simplified multilevel inverter. The simplified multilevel inverter
requires only six active switches instead of the eight required in the
conventional cascaded H-bridge multilevel inverter. In addition, two active
switches are operated at the line frequency. The number of switches used is
more hence the cost of design increases and the circuit becomes complex

8. M Rajesh, “Mechanical and dynamic mechanical behaviour of novel
glass–natural fibre intra-ply woven polyester composites” Sadhana Vol.
42, No. 7, July 2017, pp. 1215–1223 Indian Academy of Sciences DOI
10.1007/s12046-017-0676-y, et al. A novel intra-ply woven fabric polyester
composite with glass fibre yarns in one direction and natural fibre yarns in
another direction of basket-type woven fabric has been investigated for
mechanical and dynamic mechanical characteristics. Individual glass fibre
woven fabric, natural fibres woven fabric and intraply natural fibres woven
fabric composites are also investigated for the comparison purpose. Results
reveal that the intra-ply woven fabric hybridization enhances impact and
damping properties of the composite significantly than the tensile and
flexural properties. Intra-ply woven fabrics with glass fibre yarns in warp
direction and jute fibre yarns in weft direction (WGWJ) exhibit better impact
properties compared with woven fabric with other combinations.

9. PROPOSED SINGLE-PHASE STEP-UP 31-LEVEL INVERTER
o The voltage balance of dc capacitor voltages VC2 and VC3 can be
controlled by the power electronic switches S2 and S3 easily. The
easiness of balancing the dc capacitor is one of the reasons for 31-level
inverter better than the conventional inverters.
o When the absolute of the utility voltage is smaller than Vdc/2, one
power electronic switch either S2 or S3 is switched in high frequency
and the other is still in the OFF state. Which power electronic switch is
switched in high frequency depends on the dc capacitor voltages VC2
and VC3.
o If dc capacitor voltage VC2 is higher than dc capacitor voltage VC3,
power electronic switch S2 is switched in high frequency. In this
situation, the voltage source VCx in fig. 3.4 (a) is VC2, and C2 will be
discharged.

10. MATLAB/SIMULINK MODEL

11. In this the simulation is carried erroneous in two cases those
are 1. A 31 level Single phase multi string multilevel inverter 2. A
31 level three phase multi-string multilevel inverter applied to
induction machine. The following are the load specifications, by
reducing the switches we are getting single phase ac supply. The
basic simulation circuit, is a multi string inverter with a
combination of six switches. Based on the selection manner of
switches in the circuit output voltages are occured.

12. SIMULATION RESULTS
Output voltage waveform of 31 level

13. Output voltage waveform of three phase 31
level

14. Further, an experimental setup is developed using IRF460
Mosfet and the control signals are generated each
semiconductor devices using fpga Xilinx Matlab blocks are. It
can be noticed that the experimental results are made for
scaled down voltage of 31V/div due to limitations of the
available facilities in the laboratory. The measured 31-level
output voltage waveform and their corresponding load current.
Moreover, the patterns of experimental results have good
agreement with the simulation results. This validates the
effectiveness of the proposed topology is more suitable for PV
applications.

15. Output voltage and current waveforms

16. The voltage across the capacitors is maintained at 1310V to generate
31-level output voltage waveform. It can be noticed that the output voltage
is always maintained constant during load transitions from 3A to 8A peak
to peak at 1 sec. By employing a suitable controller the output voltage can
be regulated for both step changes in load as well as input voltage
changes. illustrates the measured frequency spectrum of both inverter 31-
level output voltage and load current waveforms. The %THD of the output
current is within IEEE standard limits. This shows that the proposed
configuration is well suited for PV applications. The multilevel topology
comprises of all H-span cells available in chain, each a surely understood
associated with a string. Completely another three stage multi string
multilevel inverter connected to impelling machine. The consequent
converter produces superiorly voltage levels by the entire of less dwelling
place changes contrasted with H-span setup.

17. CONCLUSION
This project proposes an enhanced single-phase step-up 31 level
inverter. Operating principle was discussed. Compared to conventional 31-
level topologies, the proposed inverter reduces the number of power
switches, diodes, size and cost of the system. Simple structure, easy control,
and high step up voltage ratio are the main features of the proposed
topology. In addition, only four switches are operated at high frequency and
the overall switching losses are reduced. Finally, MATLAB simulation results
validate the effectiveness and performance of the proposed topology.

18. REFERENCE:
[1] Ashwini N. Kadam , “Simulation And Implementation Of 31 level Inverter Based
Induction Motor Drive Based On PWM Techniques”, International Journal Of
Industrial Electronics And Electrical Engineering, ISSN: 2347-6982 Volume- 2,
Issue- 1, Jan.-2014.
[2] Manasa S, Balaji Ramakrishna S, Madhura S & Mohan M , “Design and
simulation of single phase 31 level inverter fed induction motor drive with two
cascaded h-bridge configuration” International Journal of Electrical and Electronics
Engineering (IJEEE), ISSN (print): 2231 –31284 Vol-1,Issue-4, 2012.
[3] Mr.Y.S.Bais & Dr. S.B. Deshpande, “Design Optimization and Simulation of
Three level Inverter Fed Induction Motor for Performance Improvement”,
International Journal of Electrical, Electronics and Computer Systems (IJEECS)
Vol: 02 , Issue: 02, June 2011.

19. THANK YOU