Inrush Current Suppression Circuit with Discharge Function for Airborne DC Power Supply

High-capacity bulk capacitors are necessarily set at the input terminal of power electronics equipment to meet the electromagnetic compatibility (EMC) test. However, there is an inrush current flowing the bulk capacitor during equipment startup, which is likely to trigger protection of running equipment. In this paper, the requirements of start-up inrush current in relevant standards for airborne DC power supply are introduced, and several methods of inrush current suppression are compared. Two kinds of inrush current suppression circuits based on MOSFET are introduced and their advantages and disadvantages are analyzed in detail. In order to solve the failure problem of inrush current suppression function during hot startup, an improved suppression circuit with shutdown discharge function is proposed. The circuit can timely discharge the gate voltage of the MOSFET when the input voltage drops below the threshold, which has the advantages of low loss and high reliability. Finally, the feasibility of the circuit is verified by software simulations and experiments.