Multilevel Inverters: A Comparative Study of Pulse Width Modulation Techniques

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Pulse Width Modulation Used in Multilevel Inverters

Pulse Width Modulation Used in Multilevel Inverters

ABSTRACT: The multilevel inverter topology gives the advantages of usage in high power and high voltage application with reduced harmonic distortion without a transformer. This paper presents a comparative study of nine level diode clamped inverter for constant Switching frequency of sinusoidal Pulse width Modulation and sinusoidal Natural Pulse width Modulation with switching frequency.

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Power Quality Analysis for Modular Structured Multilevel Inverter with Bipolar Variable Amplitude Multicarrier Pulse Width Modulation Techniques

Power Quality Analysis for Modular Structured Multilevel Inverter with Bipolar Variable Amplitude Multicarrier Pulse Width Modulation Techniques

Recently, for high-performance power application, multilevel converters are widely used such as static- VAR compensators, motor drives and active power filters. For high-power applications, multilevel inverter structures have the particular advantages of operation at high DC bus voltages, achieved using series connections of switching devices and a reduction in output voltage harmonics achieved by switching between multiple voltage levels The advantages of multilevel inverters are good power quality, low switching losses and high voltage capability [1–2]. Multilevel topologies are classified into three
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Comparative Analysis between Five Level Conventional and Modified Cascaded H-Bridge Five Level Inverter Using Multicarrier Pulse width Modulation Techniques.

Comparative Analysis between Five Level Conventional and Modified Cascaded H-Bridge Five Level Inverter Using Multicarrier Pulse width Modulation Techniques.

Abstract : Multilevel Inverters are getting popular and have become more attractive to researchers in the recent times for high power applications due to their better power quality and higher efficiency as compared to two level inverters. This research work presents a detailed comparative analysis of various multicarrier sinusoidal PWM schemes such as In Phase Disposition, Phase Opposition Disposition and Alternate Phase Opposite Disposition implemented on five level conventional and modified cascaded h-bridge inverters in MATLAB/SIMULINK software. Conventional five level topology uses eight switches and suffers from increased switching complexity while modified five level topology uses only five switches and is recommended to reduce switching complexity and switching losses. It also ensures less number of components, reduced size and overall cost of the system. The effect of modulation index (Ma) on the output harmonic contents in various PWM techniques is also analyzed.
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Switching Sequence Control Of Reduced Switch Count Multilevel Inverter With Multi Carrier Pulse Width Modulation

Switching Sequence Control Of Reduced Switch Count Multilevel Inverter With Multi Carrier Pulse Width Modulation

Abstract: Operation of conventional inverters like cascaded Multilevel Inverter (MLI), diode clamped multilevel inverter and flying capacitor multilevel inverter are easily performed with the various pulse width modulation techniques. The conventional MLIs are not obtaining the good efficiency due to more switching losses. To attain good efficiency with less switching losses and less Total Harmonic Distortion (THD) without changing the performance of MLIs, Reduced Switch Multilevel Inverters (RSMLI) are proposed by many researchers. But, the switching operation of RSMLI is not similar to conventional MLIs which is major task. Operation of individual switch is achieved with the help logic gates. Obtaining the logical equation for each switch with four proposed RSMLIs are analyzed and presented in this work. To obtain the pulse pattern for each switch, Multi Carrier SPWM (MCSPWM) and Multi Carrier Unipolar SPWM (MCUPSPWM) methods are used. Binary representation of PWM methods helps the researcher to analyze the switching sequence and pulse pattern of various RSMLIs with different levels of output voltage. Three 7 level and one 9 level RSMLIs are analyzed and simulated. %THD comparison is presented for proposed RSMLIs with the various PWM methods by different modulation index values.
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Design and Performance Analysis of 7-Level Diode Clamped Multilevel Inverter Using Modified Space Vector Pulse Width Modulation Techniques

Design and Performance Analysis of 7-Level Diode Clamped Multilevel Inverter Using Modified Space Vector Pulse Width Modulation Techniques

Multilevel inverter structures are the most popular for high power applications since the harmonics in the output voltage condensed significantly by using several voltage levels even though they are switched at the same frequency. The switches are connected in series for the multilevel inverters, then higher input DC voltages can be used and this reduces the withstand DC voltages for each device. For more than two decades, multi-level inverters in different topologies and control strategies have been involved in plethora of applications [1].
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A Solution to Harmonics Generation in Multi- Level Inverters using Carrier Based Phase Shift Pulse Width Modulation

A Solution to Harmonics Generation in Multi- Level Inverters using Carrier Based Phase Shift Pulse Width Modulation

Multilevel inverters are commonly modulated by using carrier based pulse width modulation techniques such as carrier based phase-shifted modulation and carrier based level-shifted modulation. Among them Carrier based Phase shift PWM (PS-PWM) have been proposed in order to reduce the harmonics at the output and to enhance the performance of the inverter. Carrier based Pulse Width Modulation (CPWM) works with a constant carrier frequency not synchronized with fundamental stator frequency which gives an optimal utilization of switching frequency. However, carrier based level-shifted modulation technique produces the best harmonic performance than the carrier based phase-shifted modulation technique [10,13]. But it is having apparent disadvantages of unequal device switching frequency and unequal device conduction periods. This is undesirable for high power applications. So the proposed method has the following advantages of equal device switching frequency and even power distribution, which is suitable for high power application [11].
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A Comparative Analysis of Different Multilevel Inverters

A Comparative Analysis of Different Multilevel Inverters

ABSTRACT: In recent days, power demand is continuously increasing. Therefore, the use of nonconventional energy sources is rapidly increasing. Among the various non-conventional sources solar energy is more promising one. The Solar energy is converted into electricity using Photovoltaic modules whose output is DC in nature. This DC is required to convert into Ac using multilevel inverters. In multilevel inverters as the number of levels in the output voltage increases, the accuracy of the system increases and the output voltage approaches nearer to the sinusoidal. As the levels in multilevel inverter increases, the complexity of the system increases due to their control strategy requirement. So at every stage user has to make a trade off with the quality of the output and complexity of the circuit. This paper deals with the 5, 7, 9, 11 levels of H bridge cascaded inverters and the simulation studies using MATLAB/Simulink software, withequal angle switching and equal area switching methods for different levels of inverters. A comparative study between different parameters of the multilevel inverters is performed for the selection of required multilevel inverter. The results obtained are also presented .
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dsPIC based Implementation of Sinusoidal Pulse Width Modulation Techninques for Multilevel Inverters

dsPIC based Implementation of Sinusoidal Pulse Width Modulation Techninques for Multilevel Inverters

To control the output voltage of MLI various modulation techniques are used such as multicarrier PWM (MCPWM), Space vector PWM, Selective harmonic PWM [4-6]. Among the mentioned PWM techniques MCPWM is most commonly used method for switching of MLI because of its ease of applicability and implementation in various topologies. On the basis of carrier MCPWM can be classified as (i) phase shifted PWM (PS-PWM) and (ii) level shifted PWM (LS-PWM). The LS-PWM can be classified further into phase disposition (PD-PWM), phase disposition (PD-PWM), phase opposition and disposition PWM (POD-PWM), alternate phase opposition and disposition PWM (APOD-PWM), and inverted phase disposition (IPD- PWM)
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Analysis of pulse width modulation control and digital control approach 
		for asymmetric DC AC cascaded H bridge multilevel inverter

Analysis of pulse width modulation control and digital control approach for asymmetric DC AC cascaded H bridge multilevel inverter

switching combination of switches in the H-bridge. Cascaded multilevel inverters can be used both in single and three phases by just adding the number of H-bridge used. The input DC source may be any DC sources such as photovoltaic cell and the final total output is the summation of individual H-bridge used .the control techniques for the H-bridge inverters are PWM technique, SVM technique etc.

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Index Terms– Hybrid multilevel inverter, Space vector pulse width modulation (SVPWM), Total harmonic distortion (THD).

Index Terms– Hybrid multilevel inverter, Space vector pulse width modulation (SVPWM), Total harmonic distortion (THD).

In the field of medium and high- power application, multilevel inverters have emerged as an attractive choice [1]. Modulation methods for hybrid multilevel inverter can be classified according to the switching frequencies methods. The most widely used techniques for implementing the pulse width modulation (PWM) strategy for multilevel inverters are sine-triangle PWM (SPWM) and space vector PWM (SVPWM). In this, SVPWM is the most popular PWM technique due to its simplicity both in software and hardware; also it can be efficiently executed in a few microseconds, achieving similar results compared with other PWM methods. There are different techniques available for implementing SVPWM for multilevel inverters. SVPWM is considered a better technique of PWM implementation, as it provides the following advantages: i) better fundamental output voltage; ii) useful in improving harmonic performance and reducing THD; and iii) easier hardware implementation in digital signal processor. The topology of a cascade multilevel inverter is shown in Fig. 1. In general, the SVPWM implementation involves the sector identification, switching-time calculation, switching vector determination and optimum switching response in selection for the inverter voltage vectors. The sector identification can be done by coordinate transformation [9] or by repeated comparison of the three phase reference voltages [1].
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Study of Multilevel Inverter Topologies and Modulation Techniques

Study of Multilevel Inverter Topologies and Modulation Techniques

For different load requirement the output voltage of the inverter needs to be varied.When ever the input dc varies the output voltage can change.Hence this variation needs to be compensated.In case of motor drives the ratio of voltage to frequency ( ) maintaned to be constant.Similarly ,in UPS the output voltage of inverter is to be regulated.This all the reasons indicate that the output voltage of the inverter is to be controlled.The pulse width modulation techniques are mainly used for voltage control.These techniques are most efficient and they control the drives of the switching devices.
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Comparative study of modulation techniques for two-level voltage source inverters

Comparative study of modulation techniques for two-level voltage source inverters

A disadvantage associated with the WM technique is the narrow range over which the modulation index may be adjusted for a given value of J, which may hinder its closed-loop use. Additionally, Table I shows that for the single- phase case SHE better utilizes the DC link voltage, and has reduced THD and wTHD at a significantly lower switching frequency when compared to WM. Multiple SHE solutions exist which provide further improvements over WM. The limitations and operating features highlighted as part of this analysis of WM are inconsistent with the claims made elsewhere [5, 6] regarding its performance. For example, this study was unable to replicate the 5-level line-to- line voltage waveforms theoretically, in simulation or practically from the standard six- pulse three-phase inverter, with an inductive load, as presented in [5].
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Advanced Carrier Based Pulse Width Modulation in Asymmetric Cascaded Multilevel Inverter

Advanced Carrier Based Pulse Width Modulation in Asymmetric Cascaded Multilevel Inverter

The multilevel inverter [MLI] is a promising inverter topology for high voltage and high power applications [1]. This inverter synthesizes several different levels of DC voltages to produce a staircase (stepped) that approaches the pure sine waveform [3-9]. Its have high power quality waveforms, lower voltage ratings of devices, lower harmonic distortion, lower switching frequency and losses, higher efficiency, reduction of dv/dt stresses and gives the possibility of working with low speed semiconductors if its comparison with the two-levels inverters. Numerous of MLI topologies and modulation techniques have been introduced and studied extensively, but most popular MLI topology is Diode Clamp, Flying Capacitor and Cascaded Multilevel Inverter (CMLI). In this paper we use a CMLI that consist ot some H-Bridge inverters and with un-equal DC. Its also namely Asymmetric Cascaded Nultilevel Inverter (ACMLI). Its most implemented because this inverter more modular and simple construction and have other advantages than Diode clamp and flying capacitor [7].
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Wavelet Modulation for Neutral Point Clamped Multilevel Inverters

Wavelet Modulation for Neutral Point Clamped Multilevel Inverters

Abstract— This paper implements a new type of modulation known as Wavelet Modulation (WM) based on non-uniform sampling and wavelet theory in a multilevel neutral-point clamped inverter. The proposed scheme is compared with other modulation techniques such as Sinusoidal Pulse Width Modulation (SPWM) and Square- wave Pulse Width Modulation (SQPWM). Simulation results show that the WM technique produces smoother current output, better output voltage, and lesser Total Harmonic Distortion (THD) as compared with the other modulation techniques.
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Sinusoidal and Space Vector Pulse Width Modulation for Inverter

Sinusoidal and Space Vector Pulse Width Modulation for Inverter

Abstract- Inverters inherently have the property of controlling output frequency but the output volt- age can’t be varied. Usually to vary output voltage we have to vary supply voltage which is not always possible for this reason PWM techniques gained momentum. Basic aim of PWM technique is to control output voltage and harmonic reduction. Pulse-width modulation (PWM), or pulse- duration modulation (PDM), is a commonly used technique for controlling power to inertial electri- cal devices, made practical by modern electronic power switches. Here we apply PWM techniques like Sinusoidal pulse width modulation (SPWM) and Space Vector Pulse width Modulation (SVPWM) to inverter and study its performance.
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Five Level Cascaded H-Bridge Multilevel Inverter using Pulse Width Modulation, In-Phase and Alternate Phase Opposition Deposition Techniques

Five Level Cascaded H-Bridge Multilevel Inverter using Pulse Width Modulation, In-Phase and Alternate Phase Opposition Deposition Techniques

The purpose of this paper is to present a simulation analysis of performance if the multicarrier sinusoidal pulse width modulation with periodic B-Spline functions based for a single-phase, five-level cascaded H-bridge inverter. The converter's structure topology and the main multicarrier modulation techniques are described below .. Through the convolution process have been obtained by the B-Spline. The simulation analysis described in Section IV has been developed in a Mat lab/Simulink environment and the results have been compared among the different modulation techniques. . The computed Total Harmonic Distortion percentage values is the parameters of comparison study among the different modulation techniques, based on B- Splin s functions
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Cascaded H-bridge Multilevel Inverter Using New Phase Shifted Carrier Pulse Width Modulation Technique

Cascaded H-bridge Multilevel Inverter Using New Phase Shifted Carrier Pulse Width Modulation Technique

Multilevel inverters are finding increased attention in industries for medium voltage and high power applications. Multilevel converters are mainly used to get desired single or three phase voltage waveforms, because of improving waveform of the inverter reduces its harmonic content, the size of the filter used and the level of electromagnetic interference generated by switching operation[1]. The required multi staircase output voltage is obtained by combining several dc voltage sources. Solar cells, fuel cells, batteries and ultra capacitors are the most common independent sources used. Multilevel converters are mainly used for medium and high power applications. There exists three commercial topologies of multilevel inverters; these are Diode clamped multilevel converters (or) Neutral Point Clamped (NPC), Flying Capacitor (FC), and Cascaded Multilevel Inverter (CMLI)[2]. The CMLI appears to be superior to other inverter topologies in application at high power rating due to its modular nature of modulation, control and protection requirements of each full bridge inverter [3].
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Analysis of Reduced Switch Topology Multilevel Inverter with Different Pulse Width Modulation Technique and Its Application with DSTATCOM

Analysis of Reduced Switch Topology Multilevel Inverter with Different Pulse Width Modulation Technique and Its Application with DSTATCOM

The pulse width modulation technique is the key part in the multilevel inverter to trigger the switches at the proper instant and to get the required level of output voltage. In this paper the following PWM methods are used for the reduced switch count MLI in order to get the required level of output voltage and the harmonic analysis is carried for the RSCMLI with these PWM techniques. For this RSCMLI topology with the PWM techniques switches S2, S4 operates at fundamental frequency and other switches are operating at switching frequency.

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A Review on Modern Pulse Width Modulation Techniques Based Inverters

A Review on Modern Pulse Width Modulation Techniques Based Inverters

ABSTRACT: The modern inverter technology for serving the society through comfort, making not only changes the domestic life style but in industries where VFD and other lifting & tackles require a new and efficient technology for betterment of performance of the drive and lifting tackles. Here the paper gives the schematic work of various scholars and comparison of different techniques of different pulse width modulation techniques for Power Electronics Inverters used for different industrial and commercial applications.

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Smart Street Lighting based on Pulse Width Modulation

Smart Street Lighting based on Pulse Width Modulation

An automatic intensity controller which acts according to the presence of vehicles is the important part of our street lighting system. IR sensor is used for the detection. Pulse width modulation technique is used for varying intensity levels. So no energy is lost in the process. The switching ON and OFF of the street light is automated using an ambient light sensor. So no manual intervention is needed and no energy loss will occur due to human error. LDR based sensor is used in the system.

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