부산대학교 도서관

Two adaptive notch filters (ANFs) based on the double integrators (ANFR) and the unbalanced synchronous reference frame control (ANFdq) were applied to the bus voltage control of a single-phase grid-connected inverter. This article also proposes a non-invasive prognostic function for the degradation of the bus capacitance using the difference between the bus ripple amplitudes estimated from the ANFs and the dq-axes currents with the nominal bus capacitance. The ANFR, ANFdq, and conventional notch filters (NFs) were experimentally validated with a 220-V, 50-Hz, 2.5-kW two-stage inverter. The bus voltage control schemes using the three NFs tuned at a fast bandwidth of 30 Hz exhibited identical performance with the grid current harmonics complied with the IEEE 1547 standard. Moreover, the ANFR and ANFdq control schemes maintain low current distortion with a variable grid frequency of 45–55 Hz. The capacitance degradation prognostic function accurately responded to a 27% reduction in the bus capacitance. Considering the control performance and computational effort, the ANFR is suitable for bus voltage control of the single-phase inverter.