scholarly journals A Simplified PWM Technique for Reduced Switch Count Multilevel Inverter

Author(s):  
Adireddy Ramesh, ◽  
O. Chandra Sekhar ◽  
M. Siva Kumar

<p>Penetration of multilevel inverters (MLI) in to high power and medium voltage application has been increasing because of its advantages. The conventional two levels inverter has high harmonic distortion which gives poor power quality. Lot of topologies has been developed to overcome the drawbacks of a two level inverter. These topologies include more number of switching devices which increases the design complexity and cost. The optimum design of inverter requires less number of switches with better quality in waveform. In this paper, a symmetrical five level and seven levels inverter configuration with simplified pulse width modulation technique is proposed. This proposed inverter requires less switches, less protection circuits along with low cost and size. The analysis of the inverter circuits is done by using Matlab/Simulink software. The synthesized staircase wave form is shown and total harmonic distortion (THD) is also measured.</p>

2021 ◽  
Vol 2062 (1) ◽  
pp. 012032
Author(s):  
Nishant Matale ◽  
Mohan Thakre ◽  
Rakesh Shriwastava

Abstract A highly popular alternative in medium voltage and high-power applications is multilevel converters because of their superior performance over conventional two-level converters. The most commonly used control methods in the case of multilevel inverters are sine pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. Among these two control strategies, SVPWM has superior performance over SPWM in terms of DC bus voltage utilization along with a reduction in total harmonic distortion (THD) of line voltages. The classical SVPWM method has various drawbacks such as computational complexity for identifying the location of reference voltage vector, sector identification, region identification, memory requirement to store lookup tables for switching vectors. The novel simplified SVPWM technique is presented for cascaded H-Bridge multilevel inverter (CHBMLI) in this paper. This simplified SVPWM method has overcome the drawbacks of the classical SVPWM method. This new technique has been implemented into a five-level CHBMLI to evaluate performance and also to compare with the SPWM method. The simulation has been performed in MATLAB software.


2020 ◽  
pp. 133-137
Author(s):  
Vivekanandan S ◽  
Vignesh C J ◽  
Kamalkumar V ◽  
Balamurugan K

This paper narrates the pulse width modulation techniques used in the multilevel inverters (MLIs). In the recent industrial revolution era, MLIs found in medium voltage high power applications especially in drives domain. The control technique employed in the MLIs decides the effective conversion of power in the circuit. The harmonic content present in the output signal will lead to the performance changes in the load side. This is indicated as measure of total harmonic distortion (THD). The output signal from MLIs is fewer harmonic when the number of levels is high without any filtering process. In addition, the control method of MLIs decides the effectiveness of the system and calculating the THD. There are different types of control methods employed in the MLIs in the various literatures. Each method differs from its benefits and suitable for driving the inverter switches for a particular application. The working of each models was discussed in detail. The models are created in MATLAB/Simulink platform and analyzed its effectiveness.


Author(s):  
N. Susheela ◽  
P. Satish Kumar

<p>The popularity of multilevel inverters have increasing over the years in various applications without use of a transformer and has many benefits. This work presents the performance and comparative analysis of single phase diode clamped multilevel inverter and a hybrid inverter with reduced number of components. As there are some drawbacks of diode clamped multilevel inverter such as requiring higher number of components, PWM control method is complex and capacitor voltage balancing problem, an implementation of hybrid inverter that requires fewer components and less carrier signals when compared to conventional multilevel inverters is discussed. The performance of single phase diode clamped multilevel inverter and hybrid multilevel inverter for seven, nine and eleven levels is performed using phase disposition, alternate phase opposition disposition sinusoidal pulse width modulation techniques. Both the multilevel inverter are implemented for the above mentioned multicarrier based Pulse Width Modulation methods for R and R-L loads.  The total harmonic distortion is evaluated at various modulation indices. The analysis of the multilevel inverters is done by simulation in matlab / simulink environment.</p>


Author(s):  
S. Usha ◽  
C. Subramani ◽  
A. Geetha

This paper deals with the design of cascaded 11 level H- bridge inverter. It includes a comparison between the 11 level H-bridge and T-bridge multilevel inverter. The cascaded inverter of higher level is a very effective and practical solution for reduction of total harmonic distortion (THD).These cascaded multilevel inverter can be used for higher voltage applications with more stability. As the level is increased the output waveform becomes more sinusoidal in nature. The inverter is designed using multicarrier sinusoidal pulse width modulation technique for generating triggering pulses for the semiconductor switches used in the device. Through this paper it will be proved that a cascaded multilevel H-bridge topology has higher efficiency than a T-bridge inverter, as whichever source input voltage is provided since input is equal to the output voltage. In T-bridge inverter, the output obtained is half of the applied input, so efficiency is just half as compared to H-bridge. The output waveform is distorted and has higher THD.  The simulation is performed using MATLAB /Simulink 2013 software.


2021 ◽  
Vol 9 (04) ◽  
pp. 34-43
Author(s):  
K. Fernand Koffi ◽  
◽  
Agoua Raoule ◽  
Diety Landry ◽  
Georges Loum ◽  
...  

The need to use SPWM controlled voltage inverters in MV, led us to examine how to filter alternative signals with filters (L-C) and (RL-C). This allowed us to decide on the use of certain formulas for calculating the elements of these filters. Likewise, we have proposed a method of calculating the resistance R by mathematical iterations without using the quality factor Q, in order to obtain a low error rate between the RMS values and the fundamental effective values and THDs respecting the standard 519 IEEE - 2014. The results of these studies obtained using the MATLAB-SIMULINK software are presented in the penultimate session of this article. Nomenclature SPWM Sinusoidal Pulse-Width-Modulation THD Total Harmonic distortion SN Apparent power of the alternating load MV Medium voltage alternating voltage (1 kV --- 50 kV) Uph phase-to-phase voltage at the ac load RMS Root Mean Squared R L C Resistance Inductance Capacitor MVDC Medium voltage direct current VSI Voltage Source Inverter


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.  


2019 ◽  
Vol 8 (2) ◽  
pp. 2650-2659

Multi-level inverter technology emerges as extremely significant choice in region of high-power medium voltage energy control. The multi-level inverter(MLI) generate a quasi sinusoidal voltage from various level of dc voltage. The proposed inverter design for 21 level cascaded MLI inverter by using Level Shifted-Sinusoidal Pulse Width Modulation (LS-SPWM) technique with new carrier and evaluate the Total Harmonic Distortion(THD). The proposed inverter design has the least number of components to lessen the cost and get better reliability of converter for medium power applications. The presented control techniques are applicable to cascaded H-bridge 21 level inverter to get better voltage regulation and thereby, lead the better efficiency,reliability and economic improvement. The selected pattern gave superior result in Total Harmonic distortion.


Author(s):  
Anshu Sharma Et.al

Many high voltage applications require three-phase inverters.  The major challenge in inverter designing is the mitigation of harmonic distortion (HD) to achieve better inverting performance. Usually, sinusoidal pulse width modulation (SPWM) is widely used to trigger the inverting switches for controlling the total HD performance in the inverter. To provide the option of multiple operating ranges the multilevel inverters are designed for higher voltage operations. This paper contributes in two passes, first, an improved SPWM modulation is generated for designing the three levels inverter. Then in the second pass, the performance of the THD is evaluated under the different load conditions using V-I measurement. THD is present in the system due to the use of switches. Therefore, this paper has evaluated the performance of the proposed improved SPWM based multilevel inverter for analysis. In order to improve the performance, the modulation index of the SPWM block is varied. The performance of the component report is also presented in the short..the output waveform of the line current and the voltage are compared; The FFT analysis is done to evaluate the comparison of THD performance. It is concluded that improving the SPWM performance and the lording conditions may improve the THD performance also.


Author(s):  
V.Jamuna Venkatesan ◽  
Gayathrimonicka Subarnan

<p>This paper presents performance features of Asymmetric Cascaded Multilevel inverter. Multilevel inverters are commonly modulated by using multicarrier pulse width modulation (MCPWM) techniques such as phase-shifted multicarrier modulation and level-shifted multicarrier modulation. Amongst these level-shifted multicarrier modulations technique produces the best harmonic performance. This work studies about multilevel inverter with unequal DC sources using level shifting MCPWM technique. The Performances indices like Total Harmonic Distortion (THD), reduction of switches and number of DC Sources are considered. A procedure to achieve the appropriate level shifting is also presented is this paper.</p>


2018 ◽  
Vol 15 (2) ◽  
pp. 417-422
Author(s):  
P. Tamilvani ◽  
K. R. Valluvan

The Extended Phase Opposition Disposition PWM (EPODPWM) technique has been applied in the two-level inverters successfully, but it is impossible to apply directly the EPODPWM technique to multilevel inverters. This paper proposes two kinds of EPODPWM techniques suitable for a cascaded multilevel inverter, analyzes the control strategy with the EPODPWM and obtains the design of its parameters. The simulation results show the proposed EPODPWM methods can get high magnitudes of the output fundamental frequency component, low total harmonic distortion and simpler digital implementation.


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