Experimental analysis of inverter performance under nonlinear loads

This paper presents a comprehensive experimental analysis of a standard single-phase PWM inverter's performance when supplying nonlinear loads. The proliferation of electronic equipment, such as switched-mode power supplies and variable-speed drives, introduces significant harmonic currents into power systems. These harmonics severely degrade the quality of the output voltage from inverters, which are critical components in renewable energy and uninterruptible power supply (UPS) systems. This study constructs a laboratory-scale testbed comprising a DC source, a full-bridge MOSFET-based inverter with sinusoidal PWM control, an LC output filter, and two distinct nonlinear loads: a diode bridge rectifier with capacitive filtering and a triac-based dimmer circuit. Performance metrics, including Total Harmonic Distortion (THD), voltage regulation, and inverter efficiency, are measured and analyzed under both linear (resistive) and nonlinear loading conditions. The results conclusively demonstrate a substantial increase in output voltage THD from <2% under linear load to over 8% under severe nonlinear loading, alongside a measurable decrease in efficiency. The paper concludes with a discussion on mitigation strategies, underscoring the necessity of advanced control techniques and harmonic filtering in modern inverter design.