Sliding Mode Control in Natural Reference Frame for Three-Phase LCL Filtered Active Front-End Converter

In this study, a sliding mode controller in natural reference frame is proposed for the three-phase active-front-end (AFE) converter. Along with the converter side inductor current, the capacitor voltage feedback is also employed to suppress the resonance of the LCL filter. Besides, PR controllers are employed instead of system equations to obtain the reference signals of the inductor current and capacitor voltage references. Thus, dependency on the filter parameters are eliminated and a robust control structure is obtained. The conventional PI controller is used to control the DC voltage control. The proposed method is validated with the processor-in-the-loop (PIL) simulation results. The obtained results proves that the proposed controller provides fast dynamic response, robust structure, and draws currents with low harmonic content from the gird.