Design and Testing of Electrical Power Subsystem of a Lean Satellite, HORYU-IV

Abstract

HORYU-IV is a lean satellite weighing 10 kg or less designed at the Kyushu Institute of Technology. It is planned to be launched with the ASTRO-H in FY2015 as a piggyback on an H-IIA rocket. The main mission of HORYU-IV is to acquire on-orbit data of discharge phenomena occurring on high-voltage solar arrays. An electrical power subsystem (EPS) is one of the HORYU-IV bus subsystems. The function of the EPS is to provide uninterrupted power to all subsystems during the satellite's lifetime. High reliability, high efficiency and simplicity are the main requirements to be considered in the design of an EPS. Generally, an EPS consists of solar arrays, rechargeable batteries, and a power control and distribution unit (PCDU). A peak power tracking topology is preferred to extract the maximum power generated by the solar arrays. The extra energy is stored in nickel-metal hydride batteries. The simple design and usage of available commercial-off-the-shelf components are the main features of the PCDU which controls the battery charging and load voltage regulation. Functional tests under different operating conditions were carried out on the designed EPS to qualify its performance. The aim of this paper is to explain the design of the EPS, and to present and analyze the test results.