Analysis of Low Cost Inverter (Three Phase – Four Switch) under Abnormal Conditions

Abstract

This revision explores the principle operation and control of a low-cost four-switch three-phase inverter (FSTPI). Dissimilar the traditional three limb six-switch inverter, the FSTPI topology uses four switches and two DC-link capacitors, thus decreasing circuit components then overall cost. Offering economic advantage, this topology simplifies control difficulty. The inverter’s performance was examined under both balanced and unbalanced load environment via MATLAB simulations. Specific attention was agreed to the consequence of changing load impedances on total harmonic distortion (THD), current and voltage waveforms, and overall efficiency. The results validate that variations in load impedance create only minor variations in THD, which in turn slightly distort the current and voltage signals. Specifically, under the first and second load states, the THD was measured at 2.87% and 5.21. Also, the study reveals an inverse relationship between THD and efficiency: when THD increased from 2.87 the efficiency decreased to 94.6%, whereas at a lower THD value of 5.21 % efficiency improved to 96.6%. Under unbalanced load conditions, the inverter exhibited only a slight increase in distortion of the AC current, while efficiency remained nearly constant compared to balanced operation. These findings confirm the suitability of the FSTPI topology for engineering applications requiring reliable performance under both balanced and unbalanced load conditions..