Solid state relay based inrush current limiter with short circuit and under voltage protection for dc-dc converters

This paper discusses about a new P-Channel MOSFET based solid state relay developed for limiting the plug-in inrush current in dc-dc converters operating on high input voltage power bus in satellites. This circuit can be used as a Solid State Relay in any on-board systems for power bus on/off operation. It provides plug-in inrush current limiting and also provides the protection against input bus under voltage and short mode failure of components in input portion of dc-dc converter. The main challenge for the proposed design is to use of minimum number of components in the design and miniaturizing the circuit. The proposed design in hybridized form can be used as a `component' for inrush current limiting inside every converter OR system and this avoids usage of extra components like electro-mechanical relay and related driver circuit. Proposed design was simulated in Pspice and a lab model was wired and tested successfully for 70 V power bus operation for power up to 160W. The test results of the proposed circuit are also presented in the paper.