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Most of the switched capacitor multi‐level inverters (SC‐MLIs) are designed with a single isolated voltage source and capacitors where voltage levels are obtained by the addition of these sources only. The common problems arise in SC‐MLIs are an unequal number of conducting paths, higher voltage drop across capacitors, sum of total inverter DC link voltages across the highest voltage rated switches and higher total standing voltage (TSV). The motivation of this work is to design a hybrid generalized SC‐MLI with reduced components aiming to maintain a constant voltage across the capacitors, to achieve higher voltage gain with minimum components used, minimum conducting paths, lower TSV, cost‐effective and an efficient inverter. A generalised SC‐MLI structure is also proposed, which can multiply the voltage across the capacitors in a binary asymmetrical manner. The design parameters of the proposed hybrid SC‐MLI topology are compared with the recently developed SC‐MLIs in terms of the number of switches, capacitors, TSV, conducting switches and industrial components cost to prove its superiority and effectiveness of the proposed inverter. The experimental prototype of a specimen 9‐level and 17‐level inverters are implemented using DS1103 and the corresponding results are presented. [ABSTRACT FROM AUTHOR]

This article presents a generalised asymmetrical cascaded multilevel inverter (MLI) for a single‐phase grid‐connected photovoltaic (PV) system and their control strategy. The control strategy, including maximum power tracking along with a suitable interface, is implemented for maximum power transfer from the PV source to the single‐phase low‐power grid. The balancing of DC‐link voltages for an asymmetrical MLI under variable solar parameters as well as grid parameter variation is implemented using the proposed control strategy. The voltage controllers maintain the constant DC‐link voltage ratio, whereas the current controller injects the sinusoidal current into the grid at unity power factor and track the grid voltage under variation of grid voltage using grid tracker. Stability analysis of the proposed grid‐connected asymmetrical inverter system is also incorporated. The whole grid‐tied PV system is simulated in the MATLAB/SIMULINK environment and the exhaustive simulation results of the system under different transient conditions are presented. In addition, a laboratory prototype for a low‐power grid‐tied PV system has been developed and implemented using DS1103. The performance of the system is also tested at varying irradiance conditions and the corresponding experimental results are also presented. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A multilevel inverter (MLI) with staircase waveform having maximum number of voltage levels at any desired voltage (or frequency) of a variable voltage, variable frequency application can play an important role in the modern power conversion system. In most of the control and modulation techniques of MLI, the number of voltage level reduces with the reduction of modulation index that increases the harmonic and total harmonic distortions (THDs). The variable voltage application of MLI using a single DC source of variable magnitude is the elementary concept of the proposed control technique. A cascaded MLI having unequal voltage sources with controlled magnitude can be used to increase the number of voltage levels. The closed-loop voltage control technique and a multi-winding transformer-rectifier based AC-link system is used to obtain the multiple variable voltage DC sources for the cascaded MLI. A nearest level modulation based control technique has been implemented for the MLI to obtain the fixed level voltage waveforms with constant THD and reduced switching losses. The whole control algorithm for a nine-level inverter is simulated and results are experimentally verified on a laboratory prototype of the three-phase induction motor drives. [ABSTRACT FROM AUTHOR]

A novel and generalised three-phase multilevel inverter (MLI) with a minimum number of switches have been proposed. The number of voltage levels can be increased to a significant value by incorporating few switches and the DC voltage sources. In the proposed three-phase MLI, the number of phase-voltage levels can be increased twice as the number of switches increased. The detailed analysis of the proposed MLI, mathematical modelling of the inverter voltage and the switching loss calculation have been done for a seven-level inverter. Modelling and simulations of the proposed generalised three-phase inverter are carried out using MATLAB/SIMULINK. The simulation results of the proposed multilevel configuration corresponding to the different voltage levels as well as at different modulation index are presented. A laboratory prototype of the proposed five-level inverter has been developed and tested for the speed control of an induction motor. The experimental results for the different modulation indexes are presented, that verifies the simulation results. A detailed comparison of the proposed MLI with the other popular multilevel configuration is presented to reflect the merits of the proposed structure for the reduced component count. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]