Abstract: In order to strengthen the ability in adopting unbalanced grid voltage, a sliding-mode control strategy of current for grid-connected converter with an LCL filter was proposed, and the sliding-mode governing equations of inner current loop and outer voltage loop were established, respectively. Dynamic quality and chattering effect of the designed sliding-mode controller were improved by using exponential rate control method. The referenced current was generated based on extended instantaneous power theory, and the objective of three-phase sinusoidal current was achieved while the second frequency fluctuation in both active and extended reactive power were eliminated. Finally, hardware-in-loop experimental platform based on RT-LAB was built. Results of comparative experiment demonstrated the correctness of proposed algorithm, as well as the excellent properties in dynamic response speed and parameter robustness.

Key words: grid-connected converter, unbalanced voltage, sliding-mode current control, hardware-in-loop, parameter robustness