Abstract

This paper proposes a control strategy based on the integration of proportional resonance (PR) and sliding mode control (SMC) for a three-phase LCL-filtered grid-connected NPC inverter. The PR control generates the capacitor voltage reference thanks to its excellent AC signal tracking capability, while the SMC control regulates the grid current. The control parameters were determined by a metaheuristic algorithm called particle swarm optimization (PSO). In the applied SMC method, the sliding surface function of phase c is derived from phases a and b. In this way, the number of sensors is reduced by removing the necessity to measure the capacitor voltage for phase c. Moreover, the chattering is effectively reduced, and a constant switching frequency is ensured by the correction applied to the sliding surface function within a narrow boundary layer. Simulation results are presented to validate the high performance of the proposed method in both steady-state and dynamic conditions, as well as its robustness against disturbances.

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