scholarly journals Three Phase Eleven Level Modular Multilevel Inverter with PD-PWM for Grid Connected System

Author(s):  
P Yogini Dr. Sujatha Balaraman,

The prominence of Modular Multilevel Inverters (MMI) is rising owing their merits of simple mechanical construction and good voltage sharing for semiconductor devices. Mostly Multilevel Inverters use more than one source; however, the effective use of all the sources at all levels is rare. Conventional Multilevel Inverters will diminish the energy efficiency of the conversion system. When compared to conventional multilevel inverter, Modular Multilevel Inverter with a high numbers of voltage levels seem to be the most suitable because of the use of an isolated dc source. This paper explores a three-phase eleven level modular multilevel inverter with phase disposition pulse width modulation technique (PD-PWM) that can extract power from all the sources at all the levels. Besides, this paper develops a synchronous d-q reference frame controller to control the current of 11kV. When compared with Reduced Switch Count based Multilevel Inverter Series/Parallel switching topologies, the Modular Multilevel Inverter provides better Total Harmonic Distortion (THD) of output voltage and utilization factor.

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>


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.


Author(s):  
Asef A. Saleh ◽  
Rakan Khalil Antar ◽  
Harith Ahmed Al-Badrani

The advantage of multilevel inverters is to produce high output voltage values with distortion as minimum as possible. To reduce total harmonic distortion (THD) and get an output voltage with different step levels using less power electronics switching devices, 15-level inverter is designed in this paper. Single-phase 11-switches with zero-level (ZL) and none-zero-level (NZL) inverter based on modified absolute sinusoidal pulse width modulation (MASPWM) technique is designed, modelled and built by MATLAB/Simulink. Simulation results explained that, multilevel inverter with NZL gives distortion percent less than that with ZL voltage. The THD of the inverter output voltage and current of ZL are 4% and 1%, while with NZL is 3.6% and 0.84%, respectively. These results explain the effectiveness of the suggested power circuit and MASPWM controller to get the required voltage with low THD.


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.


Author(s):  
Nunsavath Susheela ◽  
Satish Kumar

<p>Multilevel inverters (MLI) are becoming more popular over the years for medium and high power applications because of its significant merits over two level inverters. This paper presents an implementation of multicarrier based sinusoidal pulse width modulation technique for three phase seven level diode clamped multilevel inverter.  This topology is operated under phase opposition disposition pulse width modulation technique. The performance of three phase seven level diode clamped inverter is analyzed for induction motor (IM) load.  Simulation is performed using MATLAB/SIMULINK. Experimental results are presented to validate the effectiveness of the operation of the diode clamped multilevel inverter using field programmable gate array.</p>


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.  


Author(s):  
M. H. Yatim ◽  
A. Ponniran ◽  
M. A. Zaini ◽  
M. S. Shaili ◽  
N. A. S. Ngamidun ◽  
...  

The purpose of this study is to analyze the operation and design of symmetrical and asymmetrical multilevel inverter structures with reduced number of switching devices. In this study, the term of conventional inverter is defined as a single cascaded inverter. Specifically, the inverter operates in three complete loops and only produces 2-level and 3-level of output voltages. Usually, cascaded structure suffers from the high total harmonic distortion. Thus, by considering multilevel structure of inverter, low total harmonic distortion reduction and voltage stress reduction on switching devices can be archived. Sinusoidal pulse width modulation and modified square pulse width modulation are used as modulation techniques in switching schemes of the designed multilevel inverters. The findings indicate that, the designed multilevel structure cause low total harmonics distortion at the output voltage. Furthermore, the asymmetrical structure is producing the same output voltage levels with reduced number of switching devices compared to the symmetrical structure is experimentally confirmed. The findings show that the total harmonic distortion for 7-level (symmetrical) and 9-level (asymmetrical) are 16.45% and 15.22%, respectively.


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.


Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2148 ◽  
Author(s):  
Nataraj Prabaharan ◽  
V. Arun ◽  
Padmanaban Sanjeevikumar ◽  
Lucian Mihet-Popa ◽  
Frede Blaabjerg

This paper presents different multi-carrier unipolar trapezoidal pulse width modulation strategies for a reduced switch asymmetrical multilevel inverter. The different strategies are phase disposition, alternative phase opposition and disposition, and carrier overlapping and variable frequency that involve triangular waves as carriers with a unipolar trapezoidal wave as a reference. The reduced switch, asymmetrical multilevel inverter operation was examined for generating the seven-level output voltage using Matlab/Simulink 2009b and the results were verified with a real-time laboratory-based experimental setup using a field-programmable gate array. Different parameter analyses, such as total harmonic distortion, fundamental root mean square voltage, and distortion factor, were analyzed with different modulation indices to investigate the performance of the selected topology. Unipolar trapezoidal pulse width modulation provides a higher root mean square voltage value.


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