Neuro-fuzzy modeling and prediction of current total harmonic distortion for high power nonlinear loads

Author(s):  
Manuela Panoiu ◽  
Caius Panoiu ◽  
Loredana Ghiormez
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.


Author(s):  
Valery Safonov ◽  
Mikhail Dziuba

In this article, we present a new method of simultaneously increasing the phase quantity and regulating the rectified voltage for two 12-phase high-power rectifiers operating at a common load. Self-excited voltage inverters separately form the necessary voltages for voltage regulation and for increasing the phase quantity. The formed voltage is input with the help of a common booster transformer. Separating the inverters functions and using the common booster transformer makes it possible to reduce the installed power of the equipment significantly compared to similar circuits when the regulation range of the rectified voltage is up to 5%. Calculations show that the inverter power for increasing the phase quantity is about 3% of the rectifier power. The circuit was modeled in MatLab/Simulink and the electromagnetic processes in the rectifier were studied. The proposed method makes it possible to reduce the total harmonic distortion of the network current and the pulsation coefficient of the rectified voltage to the values typical for 24-phase rectifiers.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1531
Author(s):  
Min-Gi Cho ◽  
Sang-Hoon Lee ◽  
Hyeon-Seok Lee ◽  
Yoon-Geol Choi ◽  
Bongkoo Kang

A new circuit structure and control method for a high power interleaved dual-buck inverter are proposed. The proposed inverter consists of six switches, four diodes and two inductors, uses a dual-buck structure to eliminate zero-cross distortion, and operates in an interleaved mode to reduce the current stress of switch. To reduce the total harmonic distortion at low output power, the inverter is controlled using discontinuous-current-mode control combined with continuous-current-mode control. The experimental inverter had a power-conversion efficiency of 98.5% at output power = 1300 W and 98.3% at output power = 2 kW, when the inverter was operated at an input voltage of 400 VDC, output voltage of 220 VAC/60 Hz, and switching frequency of 20 kHz. The total harmonic distortion was < 0.66%, which demonstrates that the inverter is suitable for high-power dc-ac power conversion.


Author(s):  
Nikhil Agrawal

Multilevel inverter is a modified version of inverter. Multilevel inverter recently emerged in the area of high power and medium voltage application. In the last few decades, the great innovation has been done to improve the inverter performance, and it is challenging even today. The multilevel inverter performance is examined by total harmonic distortion and component required. In multilevel, as level increases, the total harmonic distortion value decreases, but the number of components required and driver circuit increases that make the circuit more complex and also the effect on cost. So, the challenge is to balance the bridge between cost and total harmonic distortion. This chapter simulates the various levels of conventional cascade H-bridge inverter and new proposed topology of multilevel inverter with using different modulation techniques and with using filter circuit and without filter circuit.


2018 ◽  
Vol 57 (2) ◽  
pp. 164-174
Author(s):  
Yuvaraja T ◽  
KA Ramesh Kumar

H-bridge multilevel converter is the most challenging topology from nominal to high power applications. However, when the energy is exchanged between AC side and DC side or vice versa, the fluctuation in the capacitor used in deputize unit is unavoidable. The fluctuation in the deputize unit is due to the increase in the total harmonic distortion by the capacitor in the output voltages. This total harmonic distortion is evaded by exploring the deputize unit capacitor voltage mathematically. This paper proposes the enhanced frequency shift carrier modulation in H-bridge multilevel converter to suppress the influence of fluctuation in deputize unit capacitor voltages. Enhanced frequency shift carrier modulation is considered for nonlinear compensation. The principal results of using this enhanced frequency shift carrier modulation improvise the total harmonic distortion in the output voltage of H-bridge multilevel converter. Simulation and experimental results are done using MATLAB/SIMULINK to verify the effectiveness of the proposed control scheme.


2013 ◽  
Vol 724-725 ◽  
pp. 1393-1397
Author(s):  
Xiang Zhen Li ◽  
Guang Ming Hu ◽  
Peng Xin Hou ◽  
Yu Bo Fan ◽  
Chun Lin Guo

As a class of nonlinear loads in the power system, electric vehicle chargers will produce a certain harmonic pollution for the grid. Before the construction of charging stations, it is necessary for electric vehicle charger (station) connected to the grid to simulate and predict harmonics. The models of single charger and charge station are built separately in order to simulate and analysis the impact of a single and multiple chargers on power quality. The factors of the harmonic current ratio (HRI) and the current total harmonic distortion (THDI) varied with the charging power and the number of the chargers are discussed and analyzed. The generation mechanism of harmonic counteraction and interaction between the chargers are analyzed. The simulation results show that: because of the impedance of the system and the transformer, the harmonic current ratio (HRI) and the current total harmonic distortion (THDI) both increase firstly to some extent and subsequently decrease gently with the increase of the number of the chargers in the same power charging. This phenomenon has nothing to do with the harmonic counteraction and how that happen is discussed and analysis in this paper. And the phenomenon of harmonics interaction and counteraction occurs with the increase of the number of the chargers in different power charging, and the current total harmonic distortion (THDI) declines and tends to maintain a relatively stable value.


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