Abstract - This paper deals with reduction of **total** **harmonic** **distortion** in new Cascaded H-bridge **multilevel** **inverter** topology with artificial neural network technique. This topology consists of lower blocking voltage on switches and it requires less number of dc voltage sources, power switches which results in decrease the complexity and **total** cost of the **inverter**. Moreover, a new algorithm is used to determine the magnitude of dc voltage sources for generation of all voltage levels. Artificial Neural Network (ANN) is trained by the back-propagation algorithm of the Mean Square Error (MSE) between the output and the desired value. The performance and functional accuracy of the proposed topology using ANN technique in generating all voltage levels for 31-level **inverter** are simulated using MATLAB simulink.

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According to the different types of major reference signals, PWM techniques can be divided into different categories Such as sine PWM, third **harmonic** injected PWM, sixty degree PWM, trapezoidal PWM etc. These techniques reduce the number of switching which reduces the switching loss [4]. Based on the **total** **harmonic** **distortion** (THD) analysis, third **harmonic** injected PWM (THPWM) is better among them [5]. THD is the measurement of **harmonic** **distortion** present in the output signal of the **inverter**. THD should be kept as low as possible because higher THD has unfavorable effect on power supply

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consisting of low cost, right performance and a few application which include PV panels and gas cells. Cascaded H-bridge MLI is one kind of these MLIs. Unlike the traditional **inverter**, the MLI's output voltage has a reduced THD with higher **harmonic** profile. Mathematical techniques for **harmonic** elimination are offered in some of the literatures however solving a non-linear transcendental equation set describing the SHE problem using these methods are not suitable for multi level inverters. A hybrid optimization set of rules to locate the most reliable switching angles in a **Multilevel** **Inverter** (MLI) is proposed in this paper. The switching angles are optimized to reduce low frequency harmonics. **Total** **Harmonic** **Distortion** (THD) method are implemented in order to lessen the switching losses. This paper summarizes different hybrid optimization techniques, which included the mechanisms of particle swarm optimization (PSO), genetic algorithm (GA), fuzzy logic controller and biography based algorithm which will optimize parameters. A comparative study of different algorithm has been studied.

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Abstract: In this paper, a novel procedure to find the firing angles of the **multilevel** inverters of supply voltage and, consequently, to decline the **total** **harmonic** **distortion** (THD), has been presented. In order to eliminate more harmonics in the **multilevel** inverters, its number of levels can be lessened or pulse width modulation waveform, in which more than one switching occur in each level, be used. Both cases complicate the non-algebraic equations and their solution cannot be performed by the conventional methods for the numerical solution of nonlinear equations such as Newton- Raphson method. In this paper, Cuckoo algorithm is used to compute the optimal firing angle of the pulse width modulation voltage waveform in the **multilevel** **inverter**. These angles should be calculated in such a way that the voltage amplitude of the fundamental frequency be generated while the **total** **harmonic** **distortion** of the output voltage be small. The simulation and theoretical results for the 9-levels **inverter** offer the high applicability of the proposed algorithm to identify the suitable firing angles for declining the low order harmonics and generate a waveform whose **total** **harmonic** **distortion** is very small and it is almost a sinusoidal waveform.

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Based on previous work that has been done, most researchers focus on the **harmonic** that occur on load and less concerned about the harmonics that occur at the power source. Power sources such as batteries, solar and other sources of DC supply which has a high **Total** **Harmonic** **Distortion** (THD) in term of voltage. Thus, this study is to change the power source from DC supply to supercapacitor and monitor it performance for **harmonic** reduction in output of cascaded H-Bridge **multilevel** **inverter** by using MATLAB/SIMULINK.

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This Section deals with the problem formulation of induction motor performance enhancement and the various challenges faced by the existing and proposed techniques. Evolutionary algorithms can be applied on various applications but it needs to be modified according to applications. **Harmonic** Elimination method provides an efficient method to remove lower order harmonics in various configurations of inverters. The selection of the type of **inverter** and the topology of the **inverter** plays an important role in the performance. This leads to a critical design requirement in terms of pulse wave design to be fed at the gate terminals of the various power electronics switches. The problem can also be visualized as an optimization problem with the pulse widths being the tuning parameters which needs to be optimized in terms of minimal **Total** **Harmonic** **Distortion** of the output. As mentioned above the pulse gate design can be visualized as an optimization problem which can be solved using various optimization algorithms. The research problem which we are targeting here is the design of **multilevel** inverters and their optimal selection of pulse width in order to reduce the **total** harmonics **distortion** to a minimal value, thereby improving the performance of the induction machine. Many models have been proposed for representing **harmonic** sources as well as linear components. Various network **harmonic** solution algorithms have also been published. In the following sections, we briefly summarize the well-accepted methods for **harmonic** modelling and simulations. Other chapters in this tutorial will expand upon these ideas and illustrate how to set up studies in typical situations. The most commonly used index for measuring the **harmonic** content of a waveform is the **total** **harmonic** **distortion** (THD). It is a measure of the effective value of a waveform and may be applied to either voltage or current. **Total** **harmonic** **distortion** is the contribution of all the **harmonic** frequency currents to the fundamental. Just as waveforms can be added to produce distorted waves, distorted waves may be decomposed into fundamental and **harmonic** components.

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As a result, continuous enhancements are desperately required on the potency front altogether industrial and client applications. Inverters play an important role in conversion of DC current obtained from these renewable sources of energy into AC current. once this process is done there'll be some loss in power due to the presence of harmonics and **total** **harmonic** **distortion** .So so as to achieve maximum power conversion and to prevent the device from getting damaged it is desirable to remove these harmonics and to attenuate the THD[7].

This project represent the research of **harmonic** minimization of a single phase cascaded H-bridge **multilevel** **inverter** (CHB-MLI). **Multilevel** **inverter** is used to combine a desired single or three-phase voltage waveform and also to minimize the harmonics in the electrical system. This project use cascaded H-bridge (CHB) topology due to least number of components use, output voltage level are doubled, and easy to controllled compared with diode clamp (DC) and flying capacitor (FC) topology. This research use three and five levels cascaded H-bridge **multilevel** **inverter** based on Newton-Raphson technique controller by using MATLAB/SIMULINK in order to reduce the **harmonic** in electrical system. The value of **total** **harmonic** **distortion** (THD) has been obtained based on the simulation design of three and five levels CHB-MLI.

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(2.2) To minimize **harmonic** **distortion** and to achieve adjustable amplitude of the fundamental component, up to m-1 **harmonic** contents can be removed from the voltage waveform. In general, the most significant low-frequency harmonics are chosen for elimination by properly selecting angles among different level inverters [9] [10], and high-frequency **harmonic** components can be readily removed by using additional filter circuits. According to equation (2.12), to keep the number of eliminated harmonics at a constant level, all switching angles must be less than π / 2. However, if the switching angles do not satisfy the condition, this scheme no longer exists. As a result, this modulation strategy basically provides a narrow range of modulation index, which is its main disadvantage. For example, in a seven-level equally stepped waveform, its modulation index is only available from 0.5 to 1.05. At modulation indexes lower than 0.5, if this scheme is still applied, the allowable **harmonic** components to be eliminated will reduce from 2 to 1. The **total** **harmonic** **distortion** (THD) increases correspondingly.

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Genetic Algorithm (GA) has been proposed to solve the transcendental equations, [8]-[12]. Therefore in this proposed work by using an optimizing method like GA, an attempt is made to solve SHE equation whole range of modulation index and **Total** **Harmonic** **Distortion** (THD). In this proposed work single phase cascaded H-bridge five level **inverter** is chosen for analysis.

This paper presents a genetic algorithm (GA) optimization technique to find the optimum switching angles of 11-level **inverter** with minimum number of dc sources and switches in comparison with the cascade **multilevel** **inverter** in order to minimize the **total** **harmonic** **distortion** (THD) of their output voltage waveform. Theoretical and simulation results for an 11-level converter show the efficiency of the proposed algorithm to determine the optimum angles in order to decrease the undesired harmonics and produce very high quality output voltage waveform.

Abstract: In this paper, a novel procedure to find the firing angles of the **multilevel** inverters of supply voltage and, consequently, to decline the **total** **harmonic** **distortion** (THD), has been presented. In order to eliminate more harmonics in the **multilevel** inverters, its number of levels can be lessened or pulse width modulation waveform, in which more than one switching occur in each level, be used. Both cases complicate the non-algebraic equations and their solution cannot be performed by the conventional methods for the numerical solution of nonlinear equations such as Newton- Raphson method. In this paper, Cuckoo algorithm is used to compute the optimal firing angle of the pulse width modulation voltage waveform in the **multilevel** **inverter**. These angles should be calculated in such a way that the voltage amplitude of the fundamental frequency be generated while the **total** **harmonic** **distortion** of the output voltage be small. The simulation and theoretical results for the 7-levels **inverter** offer the high applicability of the proposed algorithm to identify the suitable firing angles for declining the low order harmonics and generate a waveform whose **total** **harmonic** **distortion** is very small and it is almost a sinusoidal waveform.

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Abstract:-In present work, optimization techniques genetic algorithm (GA) and particle swarm optimization (PSO) are used to compute switching angles for the cascaded **multilevel** **inverter** for selective **harmonic** elimination and the results are compared. Switching angles obtained from PSO produced better output with less **harmonic** content. Due to better performance PSO results are used further to obtain training set for Artificial Neural Network (ANN). Hence implementation of ANN for the elimination of low order harmonics is presented. Output voltage for nine level **inverter** is obtained for both single phase and three phase Cascaded **Multilevel** **Inverter** (CMLI). Switching angles are calculated through GA and PSO for various modulation indices and for minimum **Total** **Harmonic** **Distortion** (THD). Simulation results are presented using MATLAB and m file program. Through ANN real time implementation is possible with significantly reduced lower harmonics and improved performance.

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Abstract- This paper proposes a comparison between cascaded seven level **inverter** and nine level **inverter** using Phase opposition and disposition Pulse Width Modulation control scheme. The number of switches used in the cascaded seven and nine level **inverter** is identified and the **Total** **Harmonic** **Distortion** (THD) between them is compared. As the level gets increased the number of switches gets increased so the reduced switch topology is used with Pulse Width Modulation control scheme. The number of switches used in the reduced switch seven level and nine level **inverter** topology will be less when compared to the cascaded seven level and nine level **inverter**. The **Total** **Harmonic** **Distortion** (THD) between cascaded **multilevel** **inverter** and the reduced switch **multilevel** **inverter** is compared. The results are observed by MATLAB/SIMULINK software.

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©IJRASET 2013: All Rights are Reserved 105 There are three well-known disposition methods, specifically alternative phase disposition, in phase disposition (IPD), and phase opposite disposition (POD).Comparative evaluations of these methods based on **total** **harmonic** **distortion** (THD) for **multilevel** **inverter** topologies with number of levels, switching frequencies, and modulation indices have been reported in several articles. Zero sequence injected IPD CB-PWM, or else known as the switch frequency optimal PWM technique, with marginal THD enhancement is presented to further enhance the THD performance in lower modulation with extra switching instants. Despite its simplicity, the CB-PWM technique does not offer any direct manipulation over the **harmonic** contents and also exhibits high- switching losses due to high switching frequencies; making its service into high-power applications is a big problem where high- losses are intolerable. SVM, on the other hand, can be used to manipulate harmonics at low-modulation indices and maintain desired performance characteristics of **multilevel** **inverter** in low-switching frequencies. Though efforts have been made to extend the operation of **multilevel** inverters under SVM into the over modulation region, however, as the number of levels increases, the number of inverter’s states also severely increases resulting in difficulty to compute the duty cycles, selecting the proper switching states, and to determine the sector in which the reference vector lies in.

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Abstract- In general the Induction Motor is known to be a constant speed motor. In most of the industries the induction motor is mainly used for Drive Systems. But due to the advances in computer technology the speed of the induction motor can be controlled under certain conditions. There are many ways to control the speed of the Induction Motor for variable speed applications. The basic method is 2-level **inverter** controlled by microcontroller using space vector modulation. In this method the output of the **inverter** may not be exactly sinusoidal and hence at the star point of the Induction Motor winding, causing a Voltage **Harmonic** **Distortion** in the output of the **inverter**. To minimize the voltage **harmonic** **distortion** a **multilevel** **inverter** can be used. In addition, the **harmonic** frequencies will not produce usable torque but causes heating the Induction motor windings, which are harmful to the insulation. In this paper two level and three level **inverter** fed induction motor driven at various frequencies are reported. Simulation, experimentation and the measurement of voltage **total** **harmonic** **distortion** have also been reported. In the experiment the Arduino microcontroller, Line Impedance Stabilization Network, opto- isolator, Hall Effect sensor, H-bridge **inverter** and other necessary electronic circuits are used. The measurements are recorded using Agilent make Mixed signal Oscilloscope. The Fast Fourier transform has been carried out for the experimental result, using signal analysis software. Simulation has been implemented using the MATLAB/Simulink. The results of simulation and experimentation are compared and tabulated.

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This paper concentrates on enhancing the productivity of the **multilevel** in- verter and nature of yield voltage waveform. Seven level lessened switches to- pology has been actualized with just seven switches. Essential Switching plan and Selective Harmonics Elimination were executed to diminish the **Total** Harmonics **Distortion** (THD) esteem. Selective Harmonics Elimination Stepped Waveform (SHESW) strategy is executed to dispense with the lower order harmonics. Fundamental switching plan is utilized to control the switches in the **inverter**. The proposed topology is reasonable for any number of levels. The **harmonic** lessening is accomplished by selecting fitting switching angles. It indicates would like to decrease starting expense and unpredictability con- sequently it is able for modern applications. In this paper, third and fifth level harmonics have been disposed of. Simulation work is done utilizing the MATLAB/Simulink programming results have been displayed to accept the hypothesis.

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