Adaptive Scalar PWM technique for 4S-3Φ VSI

Abstract

Voltage unbalance across dc-link capacitors is one of the major issue encountered in a 4S-3phaseVSI. The main reason of the above issue is because of the circulating phase current through the dc-link capacitor. This issue can be eliminated by using higher value of capacitors. However, it increases the cost and size of the overall system. Hence, control techniques are proposed to generate a balanced output voltage and output load current under such circumstance. This paper proposes an Adaptive Scalar Pulse Width Modulation (ASCPWM) technique to generate a balanced output voltage and output load current for 4S-3phaseVSI under unbalanced voltage condition by varying the modulation index dynamically using offset voltage element. A comparison is made among the SCPWM and ASCPWM technique. The control technique is validated by simulation using MATLAB/SIMULINK for 4S-3phaseVSI.