In recent past, numerous multilevel architectures came into existence but in this background, cascaded multilevel invert er (CM LI) is the promising structure. This type of multilevel invert er s synthesizes a medium voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltage and current wave forms, however, when the number of levels increases switching components and the count of dc sources are also increased.
This issue became a key motivation for the present paper which is devoted to investigate different types of CM LI using less number of switching components and dc sources thus finally proposed a new version of Multi-cell based CM LI. In order to verify the proposed topology, MAT LAB – simulations and hardware verification are carried out and results are presented.
- Cascade multilevel invert er
- Switching components
- High quality output voltages
SOFTWARE: MAT LAB/SIM U LINK
INVESTIGATION ON CASCADE MULTILEVEL INVERT ER:
Figure 1 (a) CH B multilevel invert er, (b) key waveform for seven-level invert er, (c) CH B multilevel invert er by employing single-phase transformers, (d) simulation verification of seven-level CH B multilevel invert er, (e) F FT spectrum.
Figure 2 (a) Asymmetrical thirteen-level CH B invert er, (b) simulation verification of thirteen-level CH B multilevel invert er, (c) FF T spectrum.
Figure 3 (a) Asymmetrical CH B multilevel invert er, (b) output voltages of each H-bridge module, (c) twenty-seven level output voltage waveform, (d) F FT spectrum.
Figure 4 (a) Asymmetrical CH B multilevel invert er using sub-cells, (b) output voltage of sub-cells, (c) thirty-one level output voltage waveform, (d) FF T spectrum.
Figure 5 (a) Hybrid CH B multilevel invert er, (b) output voltage of each H-bridge and load voltage (nine-level) waveform, (c) FF T spectrum.
Figure 6 (a) Hybrid multilevel invert er using traditional invert er, (b) output voltage waveform, (c) FF T Spectrum.
Figure 7 The proposed multi-cell CM LI.
.Figure 8 (a) The proposed 25-level asymmetric multi-cell CM LI, (b) key wave forms.
Figure 9 (a) Output voltage of first H-bridge, (b) output voltage of second H-bridge, (c) resultant output voltage with 25-levels, (d) FF T spectrum.
In this paper CM LI with sub-cells is proposed with less number of switches. To highlight the merits of proposed invert er, an in-depth investigation is carried out on symmetric, asymmetric and hybrid multilevel invert er s based on CH B top o log i es. Symmetric configuration has capacity to produce only limited number of levels in output voltage, On the counter side, symmetrical configuration can be operated in asymmetrical mode with different DC sources. However, asymmetrical configurations can produce higher number of output levels and thereby qualitative output wave forms could be generated.
hybrid CH B invert er s are also introduced, which utilizes single DC source for entire structure. Thus complexity and voltage balancing issues can be reduced. Finally proposed invert er is introduced with less number of switching components and able to produce qualitative output wave forms. To verify the proposed invert er adequate simulation is done with help of MAT LAB/sim u link. Later on, hardware variations are carried out in laboratory. Verification are quite impressive with greater number of levels in the output voltage and lower harmonic content in FF T spectrum s. Spectrum s indicate that, low order harmonics are drastically reduced. Thus power quality is significantly enhanced. Thus proposed invert er shows some promising attributes when compared with traditional CH B based architectures.
] B ab a e E, Ali l u S, La a l i S. A new general topology for cascaded
multilevel invert er s with reduced number of components based on
developed H-bridge. IEEE Trans Ind Electron 2014;61(8):3932–9.
 Malinowski Mar i us z, Go p a k u mar K, Rodriguez Jose, P e´re z
Marcelo A. A survey on cascaded multilevel invert er s. IEEE
Trans Ind Electron 2010;57(7):2197–205.
 Wu J C, Wu K D, Jo u H L, Xi a o ST. Diode-clamped multi-level
power converter with a zero-sequence current loop for three-phase
three-wire hybrid power filter. Elsevier J Elect r Power S y s t Res
 K ho u c ha Far id, Lag o n M o u n a So um i a, K he l o i Ab d e l a z i z,
Ben b o u z d Mohamed E l Ha ch e mi. A comparison of symmetrical
and asymmetrical three-phase H-bridge multilevel invert-er for
DTC induction motor drives. IEEE Trans Energy Converse
 E bra him i J, Ba b a e i E, G h a r e h p e ti an GB. A new topology of
cascaded multilevel converters with reduced number of components for high-voltage applications. IEEE Trans Power Electron