Experimental Comparison of SPWM and Modified Sine Wave Control Strategies for a Single-Phase H-Bridge Photovoltaic Inverter Based on THD Performance

The integration of photovoltaic energy into the grid or isolated loads relies on the quality of the conversion performed by the inverter, typically evaluated by the mean of the Total Harmonic Distortion (THD). This paper presents the experimental implementation of a single-phase H-bridge inverter and compares two control strategies, namely sinusoidal pulse width modulation (SPWM) and modified sine wave generation.

The experimental results show a THD of 3.35% for SPWM, compared to 50.10% for the modified sine wave. To provide a reference benchmark, a harmonic analysis was also carried out on a signal obtained from a 50 Hz low-voltage grid, yielding a measured THD of approximately 5%, consistent with the limit recommended by the IEEE 519 standard. The THD obtained with SPWM remains well below this limit, whereas the modified sine wave significantly exceeds it.

These results confirm the advantage of SPWM for the design of single-phase photovoltaic inverters and provide useful insights for their sizing, as such converters constitute a key component of the photovoltaic conversion chain, both for injecting solar energy into the electrical grid and for supplying autonomous loads directly. The proposed experimental approach also highlights the practical relevance of harmonic performance evaluation for improving the efficiency, reliability, and power quality of photovoltaic energy conversion systems.