S. P. Natarajan

Comparative study on various bipolar hybrid carrier PWM strategies for three phase five level cascaded inverter

This work presents the comparison of hybrid carrier Pulse Width Modulation (PWM) techniques for the chosen three phase Cascaded Multi Level Inverter (CMLI). In this paper, a CMLI is controlled with Sinusoidal PWM technique with Alternative Phase Opposition and Disposition and Carrier Overlapping (APOD + CO), Alternative Phase Opposition and Disposition and Phase Shift (APOD + PS), Alternative Phase Opposition and Disposition and Variable Frequency (APOD + VF), CO + VF, CO + PS, Phase Disposition and Variable Frequency (PD + VF), PS + PD, PS + VF , APOD + PD and CO + PD and the variation of Total Harmonic Distortion (THD) in the outputs is observed for various modulation indices ma. Simulation is performed using MATLAB-SIMULINK. It is seen that sinusoidal reference with PS+PD provides output with relatively low distortion. CO+VF PWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices.

Performance evaluation of unipolar PWM strategies for three phase five level diode clamped inverter

This paper presents the comparison of unipolar Pulse Width Modulation techniques for a Diode Clamped Multi Level Inverter (DCMLI). In this paper, the DCMLI is controlled with Sinusoidal PWM (SPWM) reference and Third Harmonic Injection (THI) PWM reference with Sub Harmonic PWM (SHPWM), Carrier Overlapping (CO) PWM, Phase Shift (PS) PWM, Variable Frequency (VF) PWM and the variation of Total Harmonic Distortion (THD) in their outputs is observed for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed that SHPWM strategy provides output with relatively low distortion. It is also noticed that COPWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage.

Elucidation of Various PWM techniques for a Modified Multilevel Inverter

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.

Comparative Study on Carrier Overlapping PWM Strategies for Three Phase Five Level Cascaded Inverter

paper presents the comparison of Carrier Overlapping Pulse Width Modulation (COPWM) techniques for the Cascaded Multi Level Inverter (CMLI). A CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference, Third Harmonic Injection PWM (THI PWM) reference, Sixty degree PWM reference and Stepped wave reference with Carrier Overlapping (CO) techniques. The variation of Total Harmonic Distortion (THD) in the inverter output voltage is observed when the chosen inverter is controlled by SPWM for various modulation indices. Simulation is performed using MATLAB-SIMULINK. It is observed that COPWM-C provides output with relatively low distortion for all strategies. It is also seen that COPWM-A is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage and in particular highest output is obtained for 60 degree PWM reference. KeywordsCMLI, Stepped, THIPWM, 60 degree PWM, COPWM.

Investigations on Three Phase Five Level Cascaded type FCMLI

This work presents the comparison of various multicarrier based Pulse Width Modulation (PWM) techniques for the chosen Hbridge type Flying Capacitor Multi Level Inverter (FCMLI). In this paper, a H-bridge type FCMLI is controlled with Sinusoidal PWM (SPWM) technique with Phase Disposition (PD), Phase Opposition and Disposition (POD), Alternative Opposition and Disposition (APOD), Carrier Overlapping (CO), Phase Shift (PS) and Variable Frequency (VF) PWM techniques and the variation of Total Harmonic Distortion (THD) in the output is observed by varying the modulation index. Simulation is performed using MATLAB-SIMULINK. It is observed that sinusoidal reference with PSPWM provides output with relatively low distortion and relatively lower stress on the devices. It is also seen that COPWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage and relatively lower stress on the devices.

Unipolar PWM using Trapezoidal Amalgamated Rectangular Reference Function for Improved Performance of Multilevel Inverter

In many research papers, Pulse Width Modulation (PWM) techniques have been carried out in different angles but this paper reveals a new idea to enhance the performance of MultiLevel Inverter (MLI). An attempt is made to improve the performance of MLI and also to reduce the significant third harmonic energy by using amalgamation technique. A Trapezoidal Amalgamated Rectangular (TAR) reference signal is developed to study the performance of chosen five level cascaded MLI. To validate the developed technique, simulation and experimentation are carried out through MATLAB/SIMULINK and dSPACE respectively. Three different modulation strategies, Unipolar Amalgamated Phase Disposition (UAPD), Unipolar Amalgamated Phase Shift (UAPS) and Unipolar Amalgamated Carrier Overlapping (UACO) PWM methods are developed and implemented. Harmonic analyses are done for above amalgamated reference techniques which provide better results. The simulation and experimental results closely match with each other validating the strategies presented.