The document compares cascade h-bridge multilevel voltage source inverters. It presents the basics of cascaded H-Bridge multilevel inverters, their working principle, circuit topologies, control techniques, and provides a comparative analysis of different level H-Bridge topologies in terms of total harmonic distortion and fast Fourier transform. The analysis shows that while complexity increases with more levels, total harmonic distortion decreases and output voltage increases, improving output power quality. Various level topologies are simulated using PSIM software to validate the analytical results.

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Comparative analysis of cascade h-bridge multilevel
Voltage source inverter
Abstract
In real time industrial applications, there are many limitations in extracting power from renewable
energy sources. To meet the increasing power demand, multilevel inverter is
widely used to extract power from solar cells. It synthesizes the desired ac output from severaldc sources.
This paper presents comparative analysis of different cascaded H-Bridge multilevel
inverter topologies employing low switching frequency devices to reduce thermal stress and improve
conversion efficiency.
The inverter is operated on fundamental frequency switching strategy. The present topology
provides high quality output power due to its more output levels, low thermal stress and high conversion
efficiency. This multilevel topology enables to achieve high quality output voltages and output currents
and also immense availability because of their intrinsic switches redundancy.
Cascade H-Bridge Multi level inverters also have a feature of high modularity index because each
inverter module will be seems like a module with similar circuit topology, modulation and, control
structure. So, in the case of fault in any one of these modules, it is possible to replace it with another one
quickly and easily. Moreover, with a particular control strategy, it is possible to bypass and disconnect the
faulty module without interrupting the entire load, bringing an almost continuous overall availability.
This paper presents basics of cascaded H-Bridge multilevel inverters, its working principle,
circuit topologies, control techniques, simulation & comparative analysis in terms of THD and FFT of
different level H Bridge topologies. This paper presents comparative analysis in terms of THD and FFT
of different level topologies. The different Multi level Inverter Topologies are simulated in PSIM.

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Block diagram for proposed system
Designing software and tools
MATLAB /SIMULATION Software and sim power systems tools are used. Mainly control system tools,
power electronics and electrical elements tools are used.
Conclusion
The switching sequence for cascade multilevel inverters of 5, 7, 9, 11 and 13-level has been calculated for analysis
of total harmonic distortions produced in the output voltage and complexity in computation of this sequence. It has
been found that complexity in computation of switching sequence increases with increase in number of levels as
more sets of solution are produced but the operating range of modulation index goes down. On the other part, the
THD in output voltage decrease and output voltage increase with increase in number of levels. Analytical results are
validated with simulation results for all level of CHBs. This paper has reviewed the comparative analysis in terms of
THD and FFT performance of different level CHBs done by PSIM 9.0 software. By comparison table 5, we can
conclude that as the no. level increases, the 3rd, 5th, and 7th Harmonic components are reduced when compared with
fundamental component.