Design of Observer-Based SMC Controller for Three-Phase LCL-Filtered Grid-Connected Inverters with Less Sensors

Currently, Sliding Mode Control (SMC) controller based on global stability has been successfully applied to three-phase LCL-filtered Grid-Connected Inverter (GCI). However, to achieve the global stability of the system, all three state vectors are required to provide the full information, which would utilize many sensors, increasing the cost and complexity. In this paper, an observer-based SMC controller for three-phase LCL-filtered GCI is proposed. The discrete state observer is adopted to estimate the state vectors (inverter-side current and capacitor voltage) needed for the SMC controller. In addition, the detailed design of the SMC controller and the discrete state observer are introduced. The experimental results obtained from a 3kW system demonstrate the effectiveness of the proposed control strategy.