scholarly journals Review of Multilevel Voltage Source Inverter Topologies and Analysis of Harmonics Distortions in FC-MLI

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1329 ◽  
Author(s):  
Ronak A. Rana ◽  
Sujal A. Patel ◽  
Anand Muthusamy ◽  
Chee woo Lee ◽  
Hee-Je Kim

We review the most common topology of multi-level inverters. As is known, the conventional inverters are utilized to create an alternating current (AC) source from a direct current (DC) source. The two-level inverter provides various output voltages [(Vdc/2) and (−Vdc/2)] of the load. It is a successive method, but it makes the harmonic distortion of the output side, Electromagnetic interference (EMI), and high dv/dt. We solve this problem by constructing the sinusoidal voltage waveform. This is achieved by a “multilevel inverter” (MLI). The multilevel inverter creates the output voltage with multiple DC voltages as inputs. Many voltage levels are combined to produce a smoother waveform. During the last decade, the multilevel inverter has become very popular in medium and high-power applications with some advantages, such as the reduced power dissipation of switching elements, low harmonics, and low EMIs. We introduce the information about several multilevel inverters such as the diode-clamped multilevel inverter (DC-MLI), cascaded H-bridge multilevel inverter (CHB-MLI), and flying-capacitor multilevel inverter (FC-MLI) with Power systems CAD (PSCAD) simulation. It is shown that THD is 28.88% in three level FC-MLI while THD is 18.56% in five level topology. Therefore, we can decrease the total harmonic distortion adopting the higher-level topology.

Multilevel inverters are widely used for high power and high voltage applications. The performance of multilevel inverters are superior to conventional two level inverters in terms of reduced total harmonic distortion, higher dc link voltages, lower electromagnetic interference and increased quality in the output voltage waveform. This paper presents a single phase hybrid eleven level multilevel inverter topology with reduced switch count to compensate the above mentioned disadvantages. This paper also presents various high switching frequency based multi carrier pulse width modulation strategies such as Phase Disposition PWM Strategy (PDPWM), Phase Opposition and Disposition PWM Strategy (PODPWM), Alternate Phase opposition Disposition PWM (APODPWM), Carrier Overlapping PWM (COPWM), Variable frequency carrier PWM (VFPWM), Third Harmonic Injection PWM (TFIPWM) applied to the proposed eleven level multilevel inverter and is analyzed for RL load. FFT analysis is carried out and total harmonic distortion, fundamental output voltage are calculated. Simulation is carried out in MATLAB/SMULINK.


2019 ◽  
Vol 5 (6) ◽  
pp. 9
Author(s):  
Deepa Raghuwanshi ◽  
Santosh Kumar

Multilevel inverters with a large number of steps can generate high quality voltage waveforms, good enough to be considered as suitable voltage source generators. An advanced multilevel inverter topology is proposed to optimize number of bidirectional switches. In this work the an five-level cascade H-bridge Inverter, which uses multicarrier based control structure and two capacitor with 10 switching MOSFETs topology is being presented. Analysis is done for RL and pure resistive load. The PWM strategy reduces the THD and this strategy enhances the fundamental output voltage. The experimental and simulated results show that total harmonic distortion of output voltage and current waveform shapes are 5.16 % and 5.77% respectively for RL load which are within the acceptable limits.


2018 ◽  
Vol 7 (3.1) ◽  
pp. 42
Author(s):  
B Kandavel ◽  
G Uvaraj ◽  
M Manikandan

This paper presents comparative study of Total Harmonic Distortion (THD) and its individual harmonic contents without grid and with grid for Diode clamped multi level inverter (DCMLI) and Flying capacitor clamped multilevel inverter (FCMLI) based Doubly Fed Induction Generator (DFIG) employing PI and Fuzzy logic controller (FLC). Simple method to control for a variable speed wind energy conversion system with a DFIG is connected to the grid through a diode rectifier and a diode clamped multilevel inverter (DCMLI). The DC-link voltage is controlled through a DC-DC boost converter to keep the DC voltage at constant value. Inverter is controlled by sinusoidal pulse width modulation technique, which supplies power to the grid. The THD and its harmonic content are studied for different wind speeds. DFIG fed flying capacitor multi level inverter (FCMLI) based WECS connected to load as well as grid. FCMLI is controlled through sinusoidal pulse width modulation. Voltage and current harmonics are studied. The results of both multilevel inverters are compared. It shows that the level of harmonic content of two types of multilevel inverters working at different wind speeds indicates that Total Harmonic Distortion (THD) for DCMLI has given best results.  


Multi-level inverter technology has emerged recently as a very important alternative in the area of medium-voltage high-power energy control such as ID and FD fans which runs with the help of these megawatt power drives and renewable energy integration to grid such as solar energy integration which requires pure sinusoidal voltage with less than five percent THD to synchronize to grid. For the requirement of large voltage sources(DC) in number, reduced electromagnetic interference, utilization of power electronic devices having less voltage blocking capability, less percentage of total harmonic distortion in output voltage, reduced stress on insulation they are mostly used. Various topologies are used for multilevel inverters. Among them the most commonly used is cascaded H-bridge (multi-cell). A 3-phase 11-level reduced H-bridge topology is proposed and is controlled by level shift carrier PWM in this paper. The considered topology and controlled algorithm is implemented in MATLAB/SIMULINK. The simulation results show a reduction of THD to a greater extent which will be useful in renewable areas and mega watt power drives.


2019 ◽  
Vol 16 (2) ◽  
pp. 422-427
Author(s):  
S. Karthikeyan ◽  
K. Lakshmi ◽  
S. Sivaranjani ◽  
J. Karthika ◽  
T. Nandhakumar

Multilevel inverters are mainly used in high power and medium voltage applications to reduce the required voltage rating of the power semiconductor switching devices. Nowadays multilevel inverters are also preferred for various applications regardless of the power ratings because they can essentially realize lower harmonics with lower switching frequency and lower electromagnetic interference (EMI). However, it has some disadvantages such as increased number of components, complex Pulse Width Modulation control method, and voltage balancing problem. In this paper a new topology of cascaded multilevel inverter using reduced number of switches is introduced resulting in higher output voltage levels. There era five series connected H-bridges and the DC voltage is given in the ratio n0: n: n3:2n2:10n. The output voltage having 123 levels is obtained (61 positive voltage levels, 61 negative voltage levels and zero voltage levels). Reduced Total Harmonic Distortion (THD) makes them useful for electric vehicle, FACTS and has given option for various power applications. The proposed topology results in reduction of cost and has simplicity of control system. Therefore, the overall cost and complexity are greatly reduced particularly for higher output voltage levels.


2014 ◽  
Vol 622 ◽  
pp. 127-131
Author(s):  
Vasudevan Karthikeyan ◽  
Venkatesan Jamuna ◽  
Abisha James

Applications of multilevel inverters have been widely accepted for high-power and high-voltage industry purposes. Their performance is very much superior to that of traditional two-level inverters due to reduced harmonic distortion and lower electromagnetic interference. In this paper a multilevel inverter circuit with reduced number of switches and symmetric voltage sources has been designed for hybrid generation system. The switching angles for various levels of the output are obtained by using the simple sine property. Finally, the 11-level inverter model is built using Matlab/ Simulink to validate this topology. The simulation results are presented.


In high and medium AC power applications, multilevel inverters (MLI) have significant importance in modern days. The architecture of multi-level cascaded type inverter is preferred because of reduced harmonic distortion, high quality AC output power, least switching loss and minimum switching stress. The existing method uses 8-number of switches to generate 11-level AC voltage. A new design of 15-level multilevel inverter with 6-switching devices is proposed in this paper and DC supply devices are similar to existing method, which outcomes in less switching loss, less complexity of circuit design and less cost. The DC supply for multilevel inverter is taken from solar panel with MPPT technique. The new 6-switch multilevel inverter circuit topology, switching pattern and gate pulse making is explained in this paper. The fast Fourier transform (FFT) analysis of the outputs of 11-level and 15-level of multilevel inverters are related. The new 6-switch 15 level cascaded type inverter circuit has been intended and modeled by using MATLAB software Simulink tool. The simulation outcomes are displayed with less total harmonic distortion and reduced switching loss has been achieved.


2017 ◽  
Vol 7 (1.5) ◽  
pp. 209
Author(s):  
B.Vijaya Krishna ◽  
B. Venkata Prashanth ◽  
P. Sujatha

Multilevel Inverters (MLI) have very good features when compared to Inverters. But using more switches in the conventional configuration will reduce its application in a wider range. For that reason a modified 7-level MLI Topology is presented. This new topology consists of less number of switches that can be reduced to the maximum extent and a separate gate trigger circuit. This will reduce the switching losses, reduce the size of the multilevel inverter, and cost of installation. This new topology can be used in Electrical drives and renewable energy applications. Performance of the new MLI is tested via. Total harmonic distortion. This construction structure of this multilevel inverter topology can also be increased for 9-level, 11-level and so on and simulated by the use of MATLAB/SIMULINK. A separate Carrier Based PWM Technique is used for the pulse generation in this configuration.


Author(s):  
Trong-Thang Nguyen

<p>In this study, the author analyzes the advantages and disadvantages of multi-level inverter compared to the traditional two-level inverter and then chose the suitable inverter. Specifically, the author analyzes and designs the three-level inverter, including the power circuit design and control circuit design. All designs are verified through the numerical simulation on Matlab. The results show that even though the three-level inverter has a low number of switches (only 12 switches), but the quality is very good: the total harmonic distortion is small; the output voltage always follows the reference voltage.</p>


2013 ◽  
Vol 64 (3) ◽  
pp. 143-151
Author(s):  
Farid Bouchafaa ◽  
Mohamed Seghir Boucherit ◽  
El Madjid Berkouk

Voltage source multilevel inverters have become very attractive for power industries in power electronics applications during last years. The main purposes that have led to the development of the studies about multilevel inverters are the generation of output voltage signals with low harmonic distortion; the reduction of switching frequency. A serious constraint in a multilevel inverter is the capacitor voltage-balancing problem. The unbalance of different DC voltage sources of five-level neutral point clamping (NPC) voltage source inverter (VSI) constitutes the major limitation for the use of this new power converter. In order to stabilize these DC voltages, we propose in this paper to study the cascade constituted by three phases five-level PWM rectifier, a clamping bridge and five-level NPC (VSI). In the first part, we present a topology of five-level NPC VSI, and then they propose a model of this converter and an optimal PWM strategy to control it using four bipolar carriers. Then in the second part, we study a five-level PWM rectifier, which is controlled by a multiband hysteresis strategy. In the last part of this paper, the authors study shows particularly the problem of the stability of the multi DC voltages of the inverter and its consequence on the performances of the induction motors (IM). Then, we propose a solution to the problem by employed closed loop regulation using PI regulator type fuzzy logic controller (FLC). The results obtained with this solution confirm the good performances of the proposed solution, and promise to use the inverter in high voltage and great power applications as electrical traction.


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