Impedance-Shaping-Based Stability Control of Point-of-Load Converter Integrated With EMI Filter in DC Microgrids

Abstract

The point-of-load (POL) converters integrated with the input LC filter are essential to supply the ac load in the dc microgrid. The interaction between the LC filter and the POL converter will bring instability problems to the dc-link voltage. This paper proposes a series-connected virtual impedance regulator based on the detailed small-signal model of the POL converter that feeds a linear three-phase load. The proposed method can improve the stability by modifying only the phase of the input impedance of the POL converter within the interaction frequency range. Therefore, the impact of the regulator on the converter's dynamic performance is minimized. The experiments show that the proposed stabilization methods exhibit good performance under different linear load scenarios.INDEX TERMS dc microgrids, stability, constant power load (CPL), impedance modeling, virtual impedance regulator.