Supervisor:
Professor Josep M. Guerrero

Co-Supervisor:
Professor Juan C. Vasquez

Assessment Committee:
Associate Professor Jayakrishnan Radhakrishna Pillai, AAU Energy (Chair)
Professor Ausias Garrigós Sirvent, Miguel Hernandez University of Elche, Spain
Professor Ahmed Mohammed Massoud Abdou, Qatar University

Moderator:
Associate Professor Sanjay Kumar Chaudhary

Abstract:

Within the last decades, a significant boost in the interest in space exploration has emerged among scientists, commercial organizations, governments, and in different sectors of society. The present-day efforts of space explorations from low Earth orbit to adjacent planets like the Moon, and Mars up to deep space have triggered an influx in the class of Small Satellite (SmallSat) a particular class of satellites. Due to its small volume and size, low price, and quick development time, the Cube Satellite (CubeSat) has experienced an extraordinary expansion within this class of mini-, micro-, and nanosatellites. Additionally, the advancements in integrated circuits and digital signal processing units, as well as the cost and accessibility of COTS components, have made it particularly well-positioned for rapid expansion. For scientific, earth observation, and remote sensing purposes, these satellites are fascinating. It is valuable due to its low cost, cubic shape, quick production, lightweight, and modular structure. The space operators pay remarkable attention to it.
The Electrical Power System (EPS) is the most important of the numerous subsystems that make up the SmallSat since an unstable power supply to the others frequently compromises the mission. The EPS is made up of electrical sources, storage units, and loads that are all connected via various power converters. The operation of the various power converters that make up the EPS must be carefully coordinated to achieve efficient photovoltaic power use, reliable power delivery, and ideal battery management. Due to the coordination and control of distributed generation (DG), storage, and loads in a small-scale electrical network, a SmallSat EPS can be viewed as a space microgrid in terms of power systems. At the same time, managing the charge/discharge cycle of the battery, pulse, peak, and transient power demand to prevent instability and performance degradation of the spacecraft is difficult due to the demanding requirements of their design, which include harsh radiation, space, weight, and varying temperatures. Therefore, selecting an appropriate EPS design, control, and power management are major elements for a long-lasting and successful satellite mission. In this respect, this thesis presents a comprehensive review of EPS architectures, converter topologies, and technologies dedicated to the SmallSat microgrids. Relevant technical challenges will be identified and addressed by considering space conditions to guarantee the extended satellite mission life. Besides, sophisticated design, control, and power management strategies are introduced and analyzed. As opposed to the current specific mission designs, a generalized and full-scale EPS design will be proposed where the design and modeling of PV, converter, and battery sizing will be considered and examining the power supply and demand of the satellite, which is dependent on PV array cyclic power generation and battery cell nonlinear behavior. To guarantee that necessary duties are carried out effectively and without power shortages throughout the satellite mission, first, the suitable EPS model with solar panel converter architectures and configurations including battery energy storage will be derived. The proposed design considers load profile, operating modes, eclipse, and altitude. A 3U CubeSat configuration operating under various load, temperature, and irradiance circumstances show the effectiveness of this design and power management. The design verification demonstrated good results in several operational modes across a wide range of temperatures and irradiance. Secondly, for tiny satellite applications, a comparative analysis of Maximum Power Point Tracking (MPPTs) in spinning situations will be developed. Due to the volume and mass limitations of the Nano Satellite (NanoSat), which have solar panels installed on their bodies, these satellites are designed to operate in a variety of unusual orientation scenarios. As a result, the PV system's unpredictable solar irradiation is caused, and an efficient PPT technique is required to extract the most power possible to transfer to the loads in the NanoSat Electrical Power System (EPS). To confirm the best MPPT extractions for NanoSat applications, several well-known MPPT approaches are analyzed for optimal power extraction. These include the traditional Perturb and Observe (P&O), Incremental Conductance (IC), and Ripple Correlation Control (RCC) methods. In contrast to the IC and RCC, the P&O extracts less power while oscillating more. In comparison to RCC, the IC method extracts greater power. RCC, in contrast to IC, is smoother and exhibits fewer oscillations. A power management control technique has lastly been established for SmallSat microgrid applications to avoid overcharging batteries while monitoring the PV Maximum Power Point (MPP) and Battery State of Charge (SOC) limits under a variety of solar and load scenarios. This suggested power management system uses an intelligent algorithm that can switch between maximum power point tracking and current control mode depending on the battery's state of charge to optimally manage solar power generation. The implied control and management system tends to prolong battery life through controlled charging in addition to enabling the best solar power extraction. For a seamless inter-mode transition, a local link is in charge of transmitting data about the battery's state of charge. To prevent battery overcharging, the suggested control and energy management system under incident load needs can limit PV power extraction. At various profiles of load and incident irradiance, the results are examined for power-sharing among solar PV, battery, and load to validate the effectiveness of the proposed full-scale EPS design, MPPT, and power management system for SmallSat applications. The proposed EPS design, power electronic control, and power management systems are modeled in MATLAB/SIMULINK.