Feasibility Study of Low Power PPU with COTS Components and eGaN FETs

Abstract

The Power Processing Unit (PPU) constitutes one of the most challenging parts, from both technical and business point of view, of an Electric Propulsion System (EPS). It is the module of the EPS that contains the electrical circuits responsible for providing power and control to all subsystems with varying demands and in the most efficient way, while its cost is indicatively about 50% of the total cost of an EPS. Space industries are strongly focusing on low cost PPUs while trying to present small in size and weight units with high efficiency and high reliability. In this direction, the main objective of this paper is to illustrate a feasibility study on the budget optimizations that can be achieved, in terms of power, cost, mass and size, on a space qualified low power PPU (<300W) by applying on the one hand COTS (Commercial Off-The-Self) components and on the other hand eGaN (enhancement mode Gallium Nitride) FETs as switching elements taking advantage of the improvements they may offer in the electrical and physical characteristics, retaining though the functionality and the reliability of the whole PPU. As first step, the space environment of a potential LEO mission has been clearly defined taking into account the business strategy, the potential customers and the latest trends in space market. The feasibility study results of the implementation of COTS and eGaN FETs are very promising, demonstrating essential improvements in all budget parameters of the PPU, without affecting its performance. The realization of COTS components and eGaN FETs on a synchronous Buck DC/DC converter is currently being developed in order to verify the conclusions of the study. The outcome of this activity can become the driving step forward in order to integrate the utilization of COTS and eGaN FETs also in other DC/DC converters of a PPU and develop lower in cost, size and mass and more efficient PPUs in the future.