Cristian Torres

This paper presents a modular Power Conditioning and Distribution Unit (PCDU) designed for small satellites. The proposed system features a highly adaptable architecture capable of managing a total power throughput of up to 100 W, with specific limits defined by mission-dependent thermal and redundancy configurations. Aligned with the New Space paradigm, the implementation relies on Commercial Off-The-Shelf (COTS) components, a strategy that drastically reduces development and manufacturing costs without compromising reliability. The system has been optimized for operation in harsh environments, including high vacuum, ionizing radiation, and extreme thermal gradients. The design incorporates strict redundancy and fault-tolerance criteria to provide a robust solution for critical subsystems. Comprehensive validation was performed through functional testing, Total Ionizing Dose (TID) radiation campaigns, and Thermal Vacuum (TVAC) cycles. Experimental results demonstrate that the PCDU withstands high-vacuum thermal cycling and cumulative radiation doses exceeding 75 kRad. These findings confirm that the developed unit is a cost-effective, high-reliability solution suitable for both Low Earth Orbit (LEO) and deep-space missions.

This paper introduces and describes an unregulated and isolated DC/DC converter with fixed gain for solar array power conditioning. This converter is intended for space power applications and is based on commercial of-the shelf SiC JFETs, which have been demonstrated to have exceptional electrical reliability and radiation tolerance. Cascode and supercascode structures have been used for primary and secondary power switches, ensuring minimal degradation in Total Ionizing Dose and achieving high immunity to Single Event Burnout. This paper provides comprehensive coverage of converter design and experimental validation.

This paper describes the design and implementation of a battery equalizer circuit for small satellites, developed under the New Space philosophy exclusively using commercial off-the-shelf (COTS) components. The primary objective is to ensure high reliability for mission-critical power systems while adhering to strict cost constraints. In order to achieve this objective, the design incorporates a robust analog control circuit, thereby avoiding the complexities and potential single-point failures associated with digital controllers. A comprehensive study of various cell-balancing topologies was conducted, leading to the selection, hardware implementation, and comparative analysis of the two most suitable candidates. The results of this study provide a validated, cost-effective, and reliable battery equalizer solution for developers of small satellites.

This paper presents the design of a digital twin for a 6U CubeSat electrical power system, including the solar arrays, solar array regulators, battery, power distribution unit, and load subsystems. The digital twin is validated by comparing its real-time outputs with those of the physical system. Experimental tests confirm its feasibility, showing that the digital twin’s real-time outputs closely match those of the physical system. Additionally, the digital twin can be used for control-hardware-in-the-loop and power-hardware-in-the-loop tests, allowing the real-time integration of simulated subsystems with hardware. This capability facilitates testing of new subsystems and optimization during the project’s development phases. Additionally, to demonstrate the advanced capabilities of this model, the digital twin is used to simulate the CubeSat electrical power system behavior in real time throughout a complete orbital cycle in low Earth orbit conditions. This simulation provides valuable insights into the CubeSat operation by capturing the transient and steady-state responses of the EPS components under real orbital conditions. The results obtained indicate that the digital twin significantly enhances the testing and optimization process of new subsystems during the development phases of the project. Moreover, the capabilities of the digital twin can be further augmented by incorporating real-time telemetry data from the CubeSat, resulting in a highly accurate replication of the satellite’s in-orbit behavior. This approach is crucial for identifying and diagnosing failures or malfunctions in the electrical power system, ensuring the robust and reliable operation of the CubeSat.

This paper shows the integration of the main subsystems that compose a microsatellite electric power system intended for deep space exploration. For propulsion, this satellite uses water, which is split into hydrogen and oxygen through an electrolysis process, as fuel. These two elements are then combined in a combustion process to provide the required thrust. Once the mission has been defined and the main microsatellite characteristics has been proposed, a power budget is presented, and the different subsystems are sized. Both the solar array regulator and the electrolyser power converter have been developed. Finally, the subsystems have been integrated and different tests have been carried out under different load profiles to validate the proposal.

The adoption of high bus voltage, in the range of 300 V - 400 V, is being considered for high power satellites. This has been motivated by electrical propulsion systems and increased payload capacity. The transition from 100 V to a higher bus voltage largely impacts in all power system elements, dealing this work with two major issues, solar array regulation and power distribution by solid state switches. Two novel concepts are covered in this work, a solar array regulator and a solid-state distribution switch. The application of these concepts are discussed for high voltage applications. Examples and experimental validation are also included.

This work describes the implementation of two novel Maximum Peak Power Tracking methods devised for complex I-V curves. The two methods are the Analog Global Maximum Peak Power Tracking and the Analog Global Maximum Output Power Tracking. An interplanetary mission with complex power-voltage solar array characteristics, including several local maximum power points, is considered to evaluate each technique. The two peak power tracking techniques have been integrated in an unregulated battery bus topology using synchronous buck converters as solar array regulators. Only analog electronic parts with space-qualified counterparts have been considered. Each method has been optimized individually for the best performance and then compared with the other. The experimental validation reveals that both methods find the global maximum power point with an average efficiency higher than 93%.

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.

This work describes the implementation of three Maximum Peak Power Tracking methods devised for small satellites. The three methods are the Analog oscillating Maximum Power Point Tracking, the Analog Global Maximum Peak Power Tracking and the Analog Global Maximum Output Power Tracking. An interplanetary mission (Mars-Asteroid belt) with complex power-voltage solar array characteristics, including several local maximum power points, is considered to evaluate each peak power tracking technique. The three peak power tracking techniques have been integrated in an unregulated battery bus topology using synchronous buck converters as solar array regulators. High reliability design is achieved using analog electronic parts with space-qualified counterparts. Each peak power tracking method has been optimized individually for the best performance and then compared with the others. The experimental validation suggests that the preferred method strongly depends on the expected power-voltage solar array characteristics and mission parameters.

This article describes the design and implementation of a dc–dc converter used to power a microsatellite on-board electrolyzer. The proposed topology is a four-phase interleaved synchronous buck converter with output current control. The proposed converter is single point failure free (SPFF), so in case of any individual component failure, the functionality of the system is not compromised. SPFF operation is achieved using individual protections in each buck phase, redundant output current control, and redundant clock systems. Besides, analog majority voter circuits are used to select the correct control signal after any failure and to isolate it. Detailed mathematical analysis and circuit design are presented. Furthermore, a 40-W prototype has been implemented to validate the concept. Experimental results presented show the correct performance of the system in every case and its fault tolerant capability. In addition, the ac behavior and stability of the system have been studied and verified under the full range of possible operating conditions. Finally, efficiency measurements are presented.