Power management system design and optimization for European Student Moon Orbitor (ESMO)

• Main Author: Muhammad Dzahir Mohamed Zain Affandi.
• Other Authors: Low Kay Soon
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Power electronics; DRNTU::Engineering::Electrical and electronic engineering::Electronic circuits; DRNTU::Engineering::Electrical and electronic engineering::Integrated circuits; DRNTU::Engineering::Electrical and electronic engineering::Satellite telecommunication
• Online Access: http://hdl.handle.net/10356/52176
• Institution: Nanyang Technological University

In this project, the focus will be on the design and development of the power management system for a mini-satellite under the European Student Moon Orbitor (ESMO) program. ESMO is a European Space Agency (ESA) initiative to involve the universities to build the first student satellite to orbit the Moon. NTU satellite research centre is the only university outside EU to participate in this program. The main source of power for ESMO is the Gallium Arsenide solar array which converts solar energy from the Sun into usable electricity. The buck converter designed is to be able to step down from a voltage of 80V to a bus line of 28V with the use of a specially controlled high frequency switching MOSFET through a high speed 100 MHz microcontroller C8051. Since there is a high floating voltage of 80V at the load side, it is necessary to implement a bootstrap circuitry to provide the necessary voltage to turn on the respective switches. In addition, with the help of the protection circuit, the inrush current can be modulated to operate at a maximum of 2.5A and a duration of 32ms before an internal shutdown is initiated. Overall efficiency of the power system is intensively analysed so as to ensure power losses are to be kept minimum. A performance test was conducted to compare between the asynchronous and synchronous buck converter. Synchronous buck converter has an efficiency of 87.3% which is much higher than asynchronous design of just 84.1%. Output current and voltage ripple is measured at 6.81% and 3.625%. Due to the nonlinearity of IV curve of the solar panel, the power extracted by the solar panel may not be at the maximum that the solar panel can theoretically provide. As such, a maximum-power-point-tracking (MPPT) algorithm has been implemented to achieve this goal. Two algorithm techniques have been explored namely the Perturb & Observe (P&O) and the Incremental Conductance (IC) technique. Based on the experimental results, the tracking algorithm of IC reaches as high as 92.05% which is higher than the P&O algorithm of just 89.49%. Another significant advantage of the IC is the speed of response under sudden change of environment conditions at which it can achieve 0.32 seconds response time which is 4 times faster than P&O. This characteristic is very important especially in the harsh conditions in space.