Using IIR Filter in Fractional Order Phase Lead Compensation PIMR-RC for Grid-Tied Inverters

Phase lead compensation precision dramatically affects the performance of a repetitive controller (RC). Integer order phase lead compensation of proportional integral multiresonant type RC (PIMR-RC) with low sampling frequency cannot meet the need of fine phase compensation. In addition, the digital control delay affects the actual modeling of the system, and then influences the precision phase compensation. To finely compensate the phase lag of the PIMR-RC system, this article proposes a fine fractional order phase lead compensation PIMR-RC scheme based on a novel phase lead infinite impulse response (IIR) filter. Its comprehensive synthesis is systematically detailed, including actual modeling considering 1.5-period digital control delay, IIR fractional lead filter design, stability analysis, and parameter optimization. Finally, experiments on a 2 kW prototype grid-tied inverter are successfully carried out to verify the solution.