Comparison of Current Control Methods for Grid-Connected Low-Power Single-Phase Converters

Renewable energy sources are still increasing their penetration in the electric energy system. Their connection to the grid is being done at continuously reduced power. So, a robust current controller is one of the main requirements in a grid-connected voltage source converter, namely in distributed energy sources where the connection can be made to weak grids. Additionally, achieving unity power factor with low harmonic distortion, tight DC voltage regulation and robustness to grid disturbances are required. The paper compares two current control methods: hysteresis and PWM-based, and presents simulation and experimental results demonstrating the main issues in their design.