Single-phase Asymmetrical Multilevel Inverter Research Articles

Reduced Voltage Stress Asymmetrical Multilevel Inverter With Optimal Components

The article presents a single phase asymmetrical multilevel inverter with a reduced components and low voltage stress which reduces the size and cost of the system. The structure provides a maximum output voltage of 23 levels with asymmetrical DC sources. There exists several reliability issues in lowering the total harmonic distortion (THD) by utilizing higher components in the design of MLI despite of its merits. Achieving reliability and lowering the THD is a challenging task for the researchers. The proposed 23-level MLI has been investigated with various performance parameters like total voltage standing (TSV), cost function (CF), power loss and efficiency analysis. The suggested MLI is compared with the existing topologies in the recent past and found that it has less voltage stress across the switches and cost-effective. The TSV calculations show that the proposed structure is more efficient in reducing the losses and increasing the efficiency. Hence, based on the evaluations and the comparisons made with the other topologies, it is found that the proposed MLI is well suited for the medium power applications such as FACTS, SVC, DSTATCOM and DVR. As the proposed architecture provides the 23 level output voltage values with asymmetrical DC sources, the configuration can be utilized for improving power quality in grid-connected renewable energy sources. The topology provides a less THD value which is under IEEE standards. The proposed architecture has been designed in MATLAB/Simulink and is implemented experimentally in hardware prototype in the laboratory environment.

Design and Implementation of Asymmetrical Multilevel Inverter With Reduced Components and Low Voltage Stress

Multilevel inverters with a high device count, low boosting and DC voltage imbalance are all common problems exists in the traditional topologies. In this article, a new single-phase asymmetrical multilevel inverter (MLI) that can generate 33 levels at the output with fewer components and lower total standing voltage (TSV) at the switches is presented. The multiple input sources of the proposed inverter make it suited for the use in renewable energy generating systems which have a variety of DC sources. The stress distribution among the switches is investigated that reduces the use of high rated devices with which overall cost of the inverter gets reduced. The topology can be extended by adding the circuits in series for higher levels. The performance of the inverter is calculated considering a variety of critical parameters such as TSV, cost function (CF), power loss, and efficiency calculations. The MLI is tested under dynamic load conditions with sudden load disturbances with a range of combinational loads and it has been determined to be stable throughout its operation. A detailed comparison is made based on stress across the switches, stress distribution, switches count, DC sources count, gate driver circuits, component count factor, TSV, CF, and other existing topologies using graphical representations and shown to be cost-effective and superior in all aspects. The total harmonic distortion (THD) derived from simulation and experiment complies with IEEE standards. The proposed framework has been developed in MATLAB/Simulink and tested in a laboratory environment with hardware.

An Improved Single-Phase Asymmetrical Multilevel Inverter Structure With Reduced Number of Switches and Higher Power Quality

This brief proposes an improved single-phase multilevel inverter with asymmetrical structure, consisting of ten unidirectional SiC MOSFET switches and four direct current (DC) voltage sources to produce a twenty-one voltage levels alternating current (AC). The main advantages of the proposed multilevel inverter are the simplicity and the high output power quality. The output power quality is achieved by calculating the switching angles using the half-height (HH) method, thus overcoming the problems associated with total harmonic distortion (THD) and reducing the conduction losses. Furthermore, the switching losses are reduced by using SiC MOSFET's high performance characteristics compared to their Si counterparts. To demonstrate the effectiveness of the proposed 21-level inverter, simulations using MATLAB/SIMULINK and PLECS softwares are carried out. Moreover, an experimental prototype of the inverter controlled by a C2000 Delfino-TMS320F28379D embedded board is realized to validate the results. The results indicates that THD of voltage and current are minimal, 4.2 %, and 0.3 %, respectively. The proposed multilevel inverter can be used for many applications due to its low density, low-cost and conforms to international IEEE-1547 and IEC-61727 standards.

Single‐phase hybrid multilevel inverter topology with low switching frequency modulation techniques for lower order harmonic elimination

A new single-phase asymmetrical multilevel inverter (MLI) is presented in this study. The proposed topology generates a staircase output voltage waveform with a maximum number of levels using less number of components compared to several existing and recent topologies. The basic module consists of a combination of two isolated DC sources with ten switches that produce all the possible number of levels. Other advantages of the proposed MLI include improved output voltage performance and a low blocking voltage of the switches. The low switching frequency pulse width modulation (LSF-PWM) technique has been used for the generation of gate pulses. In the LSF technique, selective harmonic elimination (SHE) and fundamental switching frequency PWM techniques have been discussed for the better output voltage waveform. The optimised switching angles with SHEPWM has been calculated using particle swarm optimisation considering the different combination of the elimination of lower order harmonics. Simulation work was carried out using MATLAB/SIMULINK, and a prototype was implemented to validate the proposed MLI module. Simulation and experimental results have been provided in the study to show the performance of the proposed topology with these modulation techniques.

A Novel Asymmetrical Single-Phase Multilevel Inverter Suitable for Hybrid Renewable Energy Sources

This paper introduces a novel single-phase asymmetrical multilevel inverter suitable for hybrid renewable energy sources. The proposed inverter consists of two isolated DC sources and six power semiconductor controlled switches. The suggested inverter is capable of generating seven-level output when the input DC voltage is taken in the ratio of 1:2. The higher magnitude DC source is fed from Photo Voltaic (PV) panels, whereas the lower magnitude DC source is fed from Wind Turbine (WT) driven Permanent Magnet DC (PMDC) generator. Both the renewable energy sources are connected to the inverter via two DC-DC boost converters connected in cascade (i.e. one for maximum power point tracking and another for DC-link voltage control). The proposed hybrid renewable energy source inverter is connected to single-phase grid via proper control systems. The complete system is simulated using MATLAB/SIMULINK and the results are presented in detail.