An electrical power system implementing fixed power point tracking with temperature compensation

Abstract

For the past decade Montana State University (MSU) researchers have been developing a Radiation Tolerant Computing System (RTCS) to support the National Aeronautics and Space Administrations (NASA) technology road map for space technology. The next iteration of this effort is a free flying CubeSat being developed in the Electrical and Computer Engineering Department named RadSat-g. This thesis addresses the Electrical Power System (EPS) of the satellite avionics in support of RTCS for RadSat-g. One of the main problems that CubeSat developers face is the small amount of solar power generated due to available space for solar cell placement on the small frame of a CubeSat. Charging the battery from the solar panels generally employ one of two types of energy transfer methods, direct energy transfer and power point tracking. Direct energy transfer's disadvantage is the strings of solar cells need to be tuned to the battery and as such has the potential to leave valuable space on the solar panel unused. Power point tracking has the advantage of the ability to utilize variable string lengths, this allows each solar panel to have the maximum number of cells and therefore exploit the maximum available power. In terms of CubeSat power availability, the RTCS has a substantial power requirement, so power point tracking is required for the satellite to be power positive. To accommodate this requirement, a new EPS needed to be researched, designed and built. This new EPS, named Phoenix v2.3 EPS, meets the needs of the RadSat-g mission while leveraging components with flight heritage from past MSU Space Science Engineering and Laboratory missions.