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.