S.P. Natarajan
Arunai Engineering College

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Elucidation of Various PWM techniques for a Modified Multilevel Inverter C.R. Balamurugan; S.P. Natarajan; R. Bensraj
Indonesian Journal of Electrical Engineering and Computer Science Vol 1, No 3: March 2016
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v1.i3.pp512-522

Abstract

This paper focuses on hybrid H-bridge cascaded MLI using two equal dc sources in order to produce a five-level output. The proposed topology reduces the number of dc sources and switching elements. This paper emphasis on various Inverted Sine Carrier PWM (ISCPWM) techniques with equal amplitude and unequal amplitude carriers. The Inverted Sine Carrier Pulse Width Modulation (ISCPWM) technique enhances the fundamental output voltage particularly at lower modulation index ranges with reduction in Total Harmonic Distortion (THD) and switching losses. Simulation is performed using MATLAB-SIMULINK. From the simulation it is observed that Variable Amplitude Inverted Sine Carrier Variable Frequency (VAISCVF) strategy provides output with relatively low distortion for all strategies. It is also seen that Variable Amplitude Inverted Sine Carrier Phase Disposition (VAISCPD) is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage.
New Bipolar Hybrid Carrier PWM Strategies for Symmetrical Multilevel Inverter C.R. Balamurugan; S.P. Natarajan; R. Bensraj
Indonesian Journal of Electrical Engineering and Computer Science Vol 14, No 2: May 2015
Publisher : Institute of Advanced Engineering and Science

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Abstract

In this paper, hybrid modulation methods suitable for H-bridge MLI are discussed. The results of experimental work using dSPACE system only are presented for three phase five level cascaded type inverter. Different hybrid carrier PWM (Pulse Width Modulation) strategies using sinusoidal reference, third harmonic injection reference, 60 degree reference and stepped wave reference for the chosen inverter are initially developed using SIMULINK. Strategies developed are then implemented in real time using dSPACE/RTI. The five level output voltages of the chosen MLI (MultiLevel Inverter) obtained using the dSPACE system based PWM strategies and the corresponding % THD (Total Harmonic Distortion) and VRMS (fundamental) are presented and analyzed. It is seen that sinusoidal reference with PS+VF (Phase shift+Variable Frequency) and PS+PD (Phase Disposition) provides output with relatively low distortion. APOD+CO (Alternative Phase Dispostion+Carrier Overlapping) and CO+PD PWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices. It is displayed that THI (Third Harmonic Injection) reference with PS+VF and CO+PS provides output with relatively low distortion. APOD+CO and CO+PS PWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices. It is observed that 60 degree reference with PD+VF provides output with relatively low distortion. CO+PD PWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices. It is noted that stepped wave reference with APOD+PD and PD+VF provides output with relatively low distortion. APOD+CO and CO+PD PWM strategy is found to perform better since it provides relatively higher fundamental RMS (Root Mean Square) output voltage and relatively lower stress on the devices. The simulation and hardware results closely match with each other. DOI: http://dx.doi.org/10.11591/telkomnika.v14i2.7362