An Oversampled Hysteresis Modulation for Shaping the Output Impedance of Droop-Controlled Boost Converters in DC Microgrids

Droop control is a common method to share power among Distributed Energy Resources (DERs) in dc microgrids. In order to reduce the dc bus voltage variations during the load transient conditions, a resistive-capacitive output impedance is needed. This can be done by implementing a fast voltage controller for the converters or using a bulky output capacitance. This paper analyses an oversampled hysteresis controller for the droop controller of boost converters. Due to the higher controller bandwidth, a resistive-capacitive output impedance is obtained with a small output capacitor. The paper proposes a design approach for hysteresis droop-controlled converters, including the design of frequency-dependent droop coefficients. Experimental results on a 3kW-380V boost prototype verify the validity of the proposed solution.