THD Analysis of a Seven, Nine, and Eleven Level Cascaded H-Bridge Multilevel Inverter for Different Loads

A multilevel inverter is implemented for generating the required staircase AC voltage of output from various steps of voltages of DC sources. The multilevel inverter gives a better harmonic spectrum and a compatible quality of output. This article delves into an analytical analysis of the total harmonic distortion (THD) of different multilevel inverters which employ a multicarrier PWM technique. This technique is implemented for operating the switches at their respective angle of conduction. This paper deals with various cascaded H-Bridge multilevel inverters (CMI) with various loads that are modelled by implementing the MATLAB/Simulink platform. The output gives a better result of the proposed model in terms that it is helpful towards reducing the THD and the losses of switching

Selective harmonic elimination in awide modulation range using modified Newton-raphson and pattern generation methods for a multilevel inverter

Considering the aim of having low switching losses, especially in medium-voltage and high-power converters, the pre-programmed pulse width modulation technique is very useful because the generated harmonic content can be known in advance and optimized. Among the different low switching frequency techniques, the Selective Harmonics Elimination (SHE) modulation method is most suitable because of its direct control over the harmonic spectrum. This paper proposes a method for obtaining multiple solutions for selectively eliminating specific harmonics in a wide range of modulation indices by using modified Newton-Raphson (NR) and pattern generation techniques. The different pattern generation and synthesis approach provide more degrees of freedom and a way to operate the converter in a wide range of modulation. The modified Newton-Raphson technique is not complex and ensures fast convergence on a solution. Moreover, multiple solutions are obtained by keeping a very small increase in the modulation index. In the previous methods, solutions were not obtainable at all modulation indices. In this paper, only exact solutions to the low-order harmonics elimination for Cascaded H-bridge inverter are reported for all modulation indices. Analytical and simulation results prove the robustness and correctness of the technique proposed in this paper. 2018 by the authors.Acknowledgments: This (publication, report, etc.) was made possible by NPRP grant # [X-033-2-007] from the Qatar National Research Fund (a member of Qatar Foundation).Scopu

Multilevel Converters: An Enabling Technology for High-Power Applications

| Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.Ministerio de Ciencia y Tecnología DPI2001-3089Ministerio de Eduación y Ciencia d TEC2006-0386

Recursive Selective Harmonic Elimination for Multilevel Inverters: Mathematical Formulation and Experimental Validation

A recursive method that eliminates +1 harmonics and their respective multiples from the output voltage of a cascaded H-bridge multilevel inverters with = 2 dc sources ( = 1, 2, 3,...) is proposed. It solves 2×2 linear systems with not singular matrices and always gives an exact solution with very low computational effort. Simulated results in three-phase five, nine, seventeen and thirty three level CHB inverters, and experimental results in five-level inverter demonstrate the validity of the method

Modified Cascaded H-Bridge Multilevel Inverter Using Particle Swarm Optimization

For more than two decades,multilevel inverters in different topologies and control strategies have been involved in many applications.In contrast to conventional three-level inverters,they are more efficient and better suited for applications requiring high power and high voltage levels.The current multilevel inverter topologies available in the market include diode clamped or neutral point clamped (NPC),capacitor clamped or flying capacitor (FC), and cascaded H-bridge (CHB).It is essential to produce an effective power converter from the perspective of cost,efficiency and output quality.These factors have lead to develop a new family of multilevel inverters known as modified CHB-MLIs of a single and three phases for five,nine and thirteen levels.This topology of the modified inverters requires fewer components compared to existing inverters (particularly in the higher levels) and requires fewer carrier signals and gate drives. Therefore,the overall cost and complexity are greatly reduced,particularly for higher output voltage levels.An important issue in the power electronic converters is the modulation control method in order to produce high quality output with a minimum distortion.As there exist many strategies for modulation, still the low-switching frequency technique is widely accepted in higher power applications.There are different optimization aims for different applications utilizing the low-switching frequency technique it is possible to increase the number of output voltage levels and produce a better sinusoidal output waveform and efficiency.The modified CHB-MLIs for five, nine and thirteen levels have a reduced number of DC power supplies and switches when compared to the conventional CHB topologies designed for the same number of voltage levels.The aim of this thesis is to investigate the performance of modified CHB-MLIs of a single and three phases for five,nine and thirteen levels based on cascaded multilevel inverter using low-switching frequency modulation scheme.The modulation method for obtaining the optimum switching angles based on Newton Raphson (NR) and Particle Swarm Optimization (PSO)control techniques have been proposed.A NR and PSO control techniques were presented for selective harmonics elimination (SHE) solution in a modified CHB-MLIs.These control techniques have been implemented through closed-loop control system using DSP TMS320F2812.In this thesis, the complete switching angles of the SHE has been developed by using a heuristic optimization technique namely PSO by solving the non-linear equation of the output voltage waveform and later validated with the conventional method NR.To validity of a low power prototype of the modified CHB-MLIs have been designed and implemented;analytical,simulation,and experimental results have been provided.The relative merits of the proposed modulation scheme based on the NR and PSO have been assessed based on modified inverters output quality and efficiency.Investigations of the proposed modulation scheme based on PSO have been revealed that the switching pattern of the adopted inverters has the capability of producing output voltage with minimal THD and high efficiency of the modified inverters.The results acquired from the simulation results the superiority of PSO over the conventional methods NR,where the THD reduction values in the three developed CHB-MLI namely five-level, nine level,and thirteen level are 15%,7.8%,and 5.2%, respectively

Real-Time Selective Harmonic Minimization for Multilevel Inverters Using Genetic Algorithm and Artificial Neural Network Angle Generation

This work approximates the selective harmonic elimination problem using Artificial Neural Networks (ANN) to generate the switching angles in an 11-level full bridge cascade inverter powered by five varying DC input sources. Each of the five full bridges of the cascade inverter was connected to a separate 195W solar panel. The angles were chosen such that the fundamental was kept constant and the low order harmonics were minimized or eliminated. A non-deterministic method is used to solve the system for the angles and to obtain the data set for the ANN training. The method also provides a set of acceptable solutions in the space where solutions do not exist by analytical methods. The trained ANN is a suitable tool that brings a small generalization effect on the angles\u27 precision and is able to perform in real time (50/60Hz time window)

Switched-battery boost-multilevel inverter with GA optimized SHEPWM for standalone application

This paper presents a boost-multilevel inverter design with integrated battery energy storage system for standalone application. The inverter consists of modular switched-battery cells and a full-bridge. It is multifunctional and has two modes of operation: the charging mode which charges the battery bank and the inverter mode which supplies AC power to the load. This inverter topology requires significantly less power switches compared to conventional topology such as cascaded H-bridge multilevel inverter, leading to reduced size/cost and improved reliability. To selectively eliminate low-order harmonics and control the desired fundamental component, nonlinear system equations are represented in fitness function through the manipulation of modulation index and the Genetic Algorithm is employed to find the optimum switching angles. A 7-level inverter prototype is implemented and experimental results are provided to verify the feasibility of the proposed inverter design

Development of Novel Multilevel Inverter with Reduced Power Switches

In recent days the usage of multilevel inverters became very essential and crucial especially on high power consuming sites. The advantages on the modularity, failure management, reliability and the waveform with less harmonic distortion at the output made the multilevel inverter to gain more attention in the current industry. Even though, multilevel inverters serving the industry with more significant advantages however they do have drawbacks such the usage of high number of power switches in their circuit and this leads to high manufacturing cost and also increase the complexity of the circuit structure. In this paper a new 9 level multilevel inverter topology has been analyzed. The proposed topology has considered factors such as reducing the power switches, reducing the total harmonic distortion and reducing the complexity of the structure

Swarm Optimization-Based Modified Selective Harmonic Elimination PWM Technique Application in Symmetrical H-Bridge Type Multilevel Inverters

The problem of elimination of harmonics and the need of a large number of switches in multilevel inverters (MLIs) have been a hot topic of research over the last decades. In this paper, a new variant swarm optimization (SO) based selective harmonic elimination (SHE) technique is described to minimize harmonics in MLIs, which is a complex optimization problem involving non-linear transcendental equation. Optimum switching angles are calculated by the proposed algorithms considering minimum total harmonic distortion (THD) and the best results are taken for controlling the operation of MLIs. The performance of the proposed algorithm is compared with the genetic algorithm (GA). Conventional MLIs have some disadvantages such as the requirement of a large number of circuit components, complex control, and voltage balancing problems. A novel seven-level reduced switch multilevel inverter (RS MLI) is proposed in this paper to recoup the need of a large number of switches. Matlab/Simulink software is used for the simulation of two symmetrical topologies, i.e., a seven-level cascaded H-bridge multilevel inverter (CHB MLI) and a seven-level (RS MLI). Simulation results are validated by developing a prototype of both MLIs. The enhancement of the output voltage waveform confirms the effectiveness of the proposed SO SHE approach

Hybrid Output Voltage Modulation (PWM-FSHE) for a Modular Battery System Based on a Cascaded H-Bridge Inverter for Electric Vehicles Reducing Drivetrain Losses and Current Ripple

This paper shows a preliminary study about the output voltage modulation of a modular battery system based on a seven-level cascaded H-bridge inverter used for vehicle propulsion. Two generally known modulation techniques, pulse width modulation (PWM) and fundamental selective harmonic elimination (FSHE), are extensively compared for such an innovative modular battery system inverter considering EVs\u27 broad torque-speed range. The inverter and the battery losses, as well as the inverter-induced current THD, are modeled and quantified using simulations. At low speeds, if the modulation index M is below 0.3, FSHE induces a high current THD (>>5%) and, thus, cannot be used. At medium speeds, FSHE reduces the drivetrain losses (including the battery losses), while operating at higher speeds, it even reduces the current THD. Thus, an individual boundary between multilevel PWM and FSHE can be determined using weightings for efficiency and current quality. Based on this, a simple hybrid modulation technique is suggested for modular battery system inverters, improving the simulated drive cycle efficiency by a maximum of 0.29% to 0.42% for a modeled small passenger vehicle. Furthermore, FSHE\u27s high speed dominance is demonstrated using a simple experimental setup with an inductive load