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Summary In this research work, a generalized structure of multilevel topology is proposed that can be extended by cascading the modules. Proposed modular topology is modified T‐type structure that requires comparative reduced number of power components than other existing structures of multilevel inverter. Each module encompasses of three DC sources and 10 power switches. Both positive and negative voltage levels can be generated without the use of H‐bridge inverter; thus, lower voltage rating power switches are employed for proposed modular topology. To generate the output voltage levels, the nearest level control is implemented on the experimental setup using dSPACE 1103 controller. To verify the performance of the proposed inverter, experimental validation of various topologies based on different algorithms is performed to generate 15‐level, 17‐level, 27‐level, and 31‐level at different load conditions. Moreover, different state‐of‐art topologies are compared with proposed topology in terms of the required number of voltage levels, DC sources, power switches, driver circuits, and total standing voltage.

This study presents the performance analysis of a new asymmetrical multi-level inverter using reduced number of switches for a single-phase grid-tied photovoltaic (PV) system. The solar PV panels of unequal power rating are connected in an appropriate manner to obtain the DC link voltages of suitable ratio for an asymmetrical cascaded multi-level inverter. The PV power, voltages as well as the current injected into the grid have been controlled using the separate maximum power point tracking, voltage controllers and a current controlled technique to achieve the maximum power with sinusoidal current with a unity power factor. The variations of DC link voltages, inverter voltage and injected grid current are simulated and are experimentally verified under the variable irradiation as well as grid voltage fluctuation. The simulation and the corresponding hardware results of the proposed reduced switch asymmetrical seven-level inverter for a low-power residential grid-tied PV system is also presented.

This study presents a generalised online switching scheme for a space vector pulse-width modulation (SVPWM)based multilevel inverter of any voltage level. The proposed SVPWM algorithm implements a generalised three-(similar to five) and seven-segment switching scheme using the three most desired switching states and one suitable redundant state for each triangle. In addition, a novel three-segment and seven-segment switching scheme has been proposed, which eliminates extra switching commutations and hence minimises the switching frequency of the devices while reducing harmonics. The proposed modulation algorithm using the generalised expressions is implemented online. The performance of the proposed novel algorithm for N-level inverter is tested experimentally on a five-level cascaded inverter at various fundamental frequencies and the experimental results are verified with the simulation results.

This study presents a simple and a generalised space vector pulse-width modulation scheme for a neutral point clamped multi-level inverter as well as cascaded inverter of any level. This modulation algorithm implements the online generation of desired switching states and their sequences through generalised expressions without any predetermined stored data in a memory look-up table. The proposed algorithm also incorporates the concept of reference vector and on-time modification combined during the over-modulation region for any level of inverter. Performance of the proposed modulation algorithm is tested experimentally through a digital signal processor-based controller for a five-level cascaded inverter with very low execution time that does not depend much on the level of inverter. The simulation waveform and the harmonic analysis of the voltage at different modulation index are presented and these are verified with the experimental results.

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Summary The proposed work shows a novel multilevel inverter (MLI) configuration to generate a large number of voltage levels with lesser number of power switches. The proposed generalized inverter comprises basic cells cascaded to each other. Each cell of the proposed inverter can generate three‐level AC voltage using the power switches of the same rating. Both single‐phase and three‐phase MLI configurations are possible for the proposed structure. To validate the performance of the proposed MLI configuration, a nine‐level inverter using six power switches and a 27‐level inverter using nine power switches are designed and simulated in the MATLAB/Simulink environment. An experimental prototype is developed in the laboratory, and the experimental results are presented to verify the simulated results. Further, to validate the effectiveness of the proposed multilevel inverter, a comparison of the proposed MLI with recently proposed multilevel inverter has been incorporated in a detailed manner.