High-Reliability Solar Array Regulator for Deep Space Exploration Micro-Satellites

This work presents a single point failure free solar array regulator design for scientific deep space exploration micro-satellites, where reliability and fault tolerance are critical design aspects. The proposed regulator is composed by six independent dc/dc Buck converters controlled by a double control loop, which can control both the battery end-of-charge voltage if the battery is fully charged, or the power generated by the solar arrays otherwise. Besides, to optimize the extracted power, each phase has an analog maximum power point tracker circuit. In addition, the regulator has a redundant over voltage protection circuit that switches off the converters in case of battery overvoltage. Furthermore, this regulator is tolerant to the failure of any component. This paper describes the electronic design of the regulator, including a detailed system stability study, as well as the implementation of a 60W prototype and the tests that have been carried out to validate the design. The main contributions of this paper are: A practical solution for a solar array regulator for space applications is proposed; a detailed stability study is developed; a overvoltage protection circuit is presented; a prototype has been implemented using commercial off-the-shelf (COTS) components with space qualified equivalent versions; and extensive functional tests have been carried out under different space representative conditions to validate fault tolerance and robustness.