Enhanced frequency shift carrier modulation for H-bridge multilevel converter to conquer the impact of instability in deputize condenser voltage

2018 ◽  
Vol 57 (2) ◽  
pp. 164-174
Author(s):  
Yuvaraja T ◽  
KA Ramesh Kumar
Keyword(s):  
Frequency Shift ◽  
High Power ◽  
Output Voltage ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Multilevel Converter ◽  
Control Scheme ◽  
Capacitor Voltage ◽  
Nonlinear Compensation ◽  
The Impact

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.

scholarly journals Performance Research of Seven Level Multi-Level Inverter with Reduced Switches using Various PWM Techniques

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1149-1154
Keyword(s):  
High Power ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Switching Topology ◽  
Switching Loss ◽  
Medium Voltage ◽  
Switching Losses ◽  
Multi Level ◽  
Low Efficiency ◽  
Performance Research

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.

scholarly journals Harmonics reduction of a five-level inverter by unbalanced carriers and over-modulation techniques

2018 ◽  
Vol 7 (3) ◽  
pp. 1059
Author(s):  
Mustafa Fawzi Mohammed ◽  
Ali Husain Ahmad ◽  
AbdulRahim Thiab Humod
Keyword(s):  
Fundamental Frequency ◽  
Output Voltage ◽  
Single Phase ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Modulation Method ◽  
Labview Software ◽  
Design And Implementation ◽  
Modulation Techniques ◽  
Multi Level

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.  

Research on the High Frequency Realization of High-Power Inverter

2011 ◽  
Vol 383-390 ◽  
pp. 1077-1083
Author(s):  
Run Hua Liu ◽  
Gang Wang
Keyword(s):  
High Power ◽  
High Frequency ◽  
Output Voltage ◽  
Harmonic Distortion ◽  
Soft Switching ◽  
Multilevel Inverter ◽  
Switching Frequency ◽  
Switching Losses ◽  
Simulation And Experiment

The paper presents the inverter method which based on cascade multilevel inverter and MOSFET-assisted soft-switching of IGBT and modulation strategy against the double requirement of high-power inverter and high frequency. The method can effectively improve the output voltage, reduce harmonic distortion and switching losses, improve the switching frequency and meet the double requirement of the high-power inverter and high frequency. The method proved to be feasible by simulation and experiment.

scholarly journals Circulating Current Suppression Control in Surrogate Network of MMC- HVDC System

2020 ◽  
Vol 8 (6S) ◽  
pp. 29-34
Keyword(s):  
Output Voltage ◽  
Electromagnetic Transients ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Voltage Balancing ◽  
Hvdc System ◽  
Circulating Current ◽  
Capacitor Voltage ◽  
Circulating Currents ◽  
Three Phases

Modular multilevel converter consists of hundreds of submodules (SMs) like half bridge and full bridge converters etc. These hundreds of SMs and electrical nodes poses challenges while computing electromagnetic transients (EMTs). This problem becomes more complex while computed in real-time. To overcome this, an equivalent topology to model MMC arm/valve called surrogate network is utilized. But, the major ambiguity integrated with surrogate network model is SM capacitor voltage balancing. This leads to variation in voltage among the three phases which are parallel and produces circulating current between the three phases. A control circuitry is proposed in this paper to suppress/minimize circulating currents between the phases. Apart from circulating current suppression, the ‘ac’ output voltage is also enhanced at the converter with this proposed controller. Simulation is carried out in RSCAD software using RTDS simulator.

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