Minimizing total harmonic distortion in a multi-level based WPT system

Author(s):  
Hamid Reza Rahnamaee ◽  
Udaya K. Madawala ◽  
Duleepa J. Thrimawithana
2019 ◽  
Vol 8 (2S8) ◽  
pp. 1149-1154

A inverter is basically a device that usually converts DC to AC voltage without causing any power loss, applicable to only low to medium voltage applications. But in case of medium to high power applications, it has demerits like high switching losses, reduced cost and low efficiency. To overcome these demerits a Multilevel inverter applicable to high voltage and high-power applications which have low total harmonic distortion (THD) is introduced. This paper is mainly focused on seven-level inverter with five switches and four dc sources. with low total harmonic distortion, less switching loss without adding any complexity to the circuit. The switching topology is integrated with various SPWM techniques like Phase Disposition (PD), Phase Opposition Disposition (POD) and Anti Phase Opposition Disposition (APOD). For better performance of the inverter above three PWM techniques will be compared and analyzed to find the low THD configuration. The simulation of switching topology is done by MATLAB/Simulink.


2018 ◽  
Vol 7 (3) ◽  
pp. 1059
Author(s):  
Mustafa Fawzi Mohammed ◽  
Ali Husain Ahmad ◽  
AbdulRahim Thiab Humod

The most concerns in the inverter's design are about, how to make the output voltage of the inverter sinusoidal at the desired fundamental frequency with low total harmonic distortion (THD). This paper presents a design and implementation of single-phase five-level inverter which is powered by single dc source and based on T-type multi-level inverters construction. The proposed inverter is built mainly by six IGBTs and two diodes. The used modulation technique is based on using two triangular carriers at 2000 Hz frequency and shifted by phase opposition disposition (POD) method. The carriers are made slightly unbalanced with their amplitudes. The over-modulation method is also introduced in the design to get the lowest possible THD effect without using filters. The inverter is simulated by MATLAB SIMULINK, implemented practically, and tested with the help of LabVIEW software.  


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):  
Kureve D. Teryima ◽  
Goshwe Y. Nentawe ◽  
Agbo O. David

<p>This paper proposes a switching control for a cascaded H-bridge inverter structure with reduced switches which is used to improve the THD performance of a single phase five level CHB MLI. The multi level inverter is simulated for the conventional carrier overlapping APOD and the proposed carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltages are observed for both PWM control techniques. The performance of the symmetric CHB MLI is simulated using MATLAB-SIMULINK. It is observed that the proposed carrier overlapping APODPWM provides output with relatively low THD as compared to the conventional carrier overlapping APODPWM.</p>


Author(s):  
Hatef Firouzkouhi

A new concept in control of cascaded H-Bridge multi-level inverters is proposed in this paper. According to this concept, switching angles are considered to be independent from the fundamental voltage. A polynomial term is presented to show the relation between switching angles and DC voltages. Based on this concept, Total Harmonic Distortion (THD) calculations are updated and proved to be independent from the fundamental voltage. Thus, once calculated for minimum THD, the switching pattern can be used for any required level of output voltage. To examine the effectiveness of the proposed method, it is applied in control of an eleven level inverter. The simulation results are demonstrated and verified through experiments with a setup controlled by Xilinx SPARTAN3 family FPGA (XC3S400-PQG208).


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