Improving Short-Circuit Currents in DC Microgrids Using Coupled-Inductor Filters

Conventionally, dc-dc converters need a large input/output side electrolytic capacitor to suppress the voltage ripple which is caused by the PWM switching and achieve the desired voltage stable performance for the dc microgrid application. However, the large capacitor will increase the dc-bus short-circuit current dramatically when the short-circuit occurs. In this paper, a coupled-inductor-based filter, which ensures the lower voltage ripple and lower short-circuit current of the dc microgrid, is proposed to realize the electrolytic capacitor. Moreover, the long lifetime film capacitor can be used to replace the electrolytic capacitor by reducing the required capacitance. The computer simulations and hardware experimental results are shown to verify the performance of the proposed coupled-inductor filter and short-circuit current reduction technique.