Implementation of sigma-delta modulation controller for single-phase three-wire inverter in stand-alone operation applied for hybrid generation system for residential houses

In recent years, introduction of distributed generations and energy storages to residential houses is promoted to solve energy and environmental problems. The distributed generation system with energy storage can be operated in stand-alone operation. In that case, the electrical power is supplied to ac loads in houses by a single-phase 3-wire inverter. Control robustness and low distortion output waveform under balanced, unbalanced, non-linear load, and load changing conditions are required for the inverter. In this paper, the authors proposed the sigma-delta (Σ-Δ) modulation control scheme for a single-phase 3-wire inverter. Some experiments to demonstrate the validity of this control scheme were carried out and results of inverter losses and the total harmonic distortion (THD) of load voltage were compared with conventional proportional and resonant (PR) control under several sampling frequency conditions.