ASSESSMENT OF VARIOUS BIPOLAR VARIABLE AMPLITUDE SPWM STRATEGIES FOR A THREE PHASE TRINARY SOURCE NINE LEVEL INVERTER

Abstract

This paper presents an inclusive analysis of various Bipolar Variable Amplitude Pulse Width Modulation (BVAPWM) techniques with Sinusoidal reference for three phase Trinary Source Nine level cascaded inverter. A new approach of nine levels is for medium voltage applications. The proposed topology adopts various new schemes such as constant switching frequency with variable amplitude triangular carrier control freedom degree combination concepts, which were developed and simulated for the chosen inverter using MATLAB-SIMULINK. The chosen asymmetrical inverter uses reduced number of switching devices, lower voltage stress of devices, lower electromagnetic interference, low level of high frequency noise, better RMS voltage, lower common-mode voltage and thus reducing losses and low THD in comparison with the literature of exploited conventional topologies existing so far. The configuration of the circuit is simple and easy to control. Performance factors such as %THD, VRMS where measured and Distortion Factor (DF) of output voltage were calculated for different modulation indices and the results are compared. It is observed that BVAPODPWM technique provides minimum THD, BVAAPODPWM technique provides lower DF and BVACOPWM technique provides higher fundamental VRMS output voltage.

Keywords

• Asymmetrical inverter
• Bipolar variable amplitude
• Modulation
• minimum switches
• Multicarrier sinusoidal pulse width
• Total harmonic distortion
• Trinary source.