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Analog Maximum Peak Power Tracking Techniques for Small Satellites
Abstract
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.
... The output of the internal transconductance error amplifier is configured to be externally driven by the outer voltage control loops. When operating in MPP mode, an autonomous analog oscillating maximum power point tracker (MPPT) [16] generates the reference for the voltage control loop, ensuring that the input voltage oscillates around the maximum power point voltage. Figure 3 shows the block diagram of one regulator. ...
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.
CubeSats have been popular for space research due to lower cost, faster development, and easier deployment. The electrical power system (EPS) is one of the significant subsystem for the CubeSat since it handles power generation,
energy storage, and power distribution to all other subsystems. Therefore, the design of EPS becomes crucial for successful CubeSat mission, wherein the first step is the selection of EPS architecture. The main objective of this paper is to present an extensive review of all the conventional and emerging EPS architectures of CubeSats. A total of seventeen categories of CubeSat EPS architectures have been identified, classified, and the operational aspects of these architectures are presented in addition to a qualitative comparison. This study is expected to provide a useful reference guide for all the researchers and developers working in the area of CubeSats EPS. Also, some of the potential research topics are provided to further exploration and innovation for the CubeSat EPS.
This investigation outlines preliminary trajectory design for NASA’s sail-based Solar Cruiser spacecraft, selected on December 3, 2020, to be a secondary payload launched with the Interstellar Mapping and Acceleration Probe (IMAP) in 2025. Trajectory optimization is carried out to ensure that Solar Cruiser can successfully reach a halo orbit about a Sun-Earth sub-L1 Lagrange point in under one year using only solar sail propulsion. Trade studies are performed to identify optimal trajectories subject to restrictions on sail incidence angles and deployment times, and off nominal initial-conditions are examined to determine the feasibility of the baseline mission profile. Results, thus far, show that Solar Cruiser can be incorporated as a secondary payload on IMAP while satisfying tight operational restrictions. However, additional work must be done to mitigate risks from large launch vehicle injection errors.
Abstract—CubeSats have been widely used for space research due to lower cost and faster development. Electric power system (EPS) is one of the key subsystem of CubeSat which powers all the other subsystems. One of the important step in the EPS design is the selection of EPS architecture which should be done considering overall efficiency, battery size, reliability, and simplicity of control. In literature, a general comparison between different architectures is performed without considering the mission parameters, power generation profile, and load profile based on the operational modes. Thus, the best possible EPS architecture may not be selected in the design phase. Therefore, the main objective of this paper is to develop a systematic method-ology to compare various peak power tracking EPS architectures of CubeSat in terms of orbital efficiency for all possible modes of operation, component count, reliability, and battery size to meet the required number of cycles of charge/discharge for the given mission duration. The proposed methodology has been demonstrated using the real data and scenarios of MYSAT-1, which is an 1U CubeSat developed and launched by Khalifa University. The results demonstrate that EPS architecture with series connected maximum power tracking converters for solar panels and unregulated dc-bus has the highest efficiency for all operating modes, lower component count, higher reliability, and minimum battery capacity or longer life time for the same battery specifications.
The parallel connection of many different strings and the tracking of the whole solar array to a single operating point effectively limits the available solar array power. The referred power loss increases with the mismatching of the strings, which may depend on several different parameters (temperature, sun illumination, degradation, harness losses, etc). This paper introduces an extremely simple and accurate maximum power point tracker, allowing solar array power segregation with small increase in number of components. By using a Step-Up converter as Array Power Regulator, the proposed concept operates the solar array and related items (such as Solar Array Drive Mechanisms) with voltages below the bus, which reduces the risk of arcing.-Also, over the years, there have been a number of cases where severe in-orbit power losses have been detected. These have been related to the damage caused by sustained arcing within the Solar Array Drive Mechanism. It is known that such an event is voltage dependant, so that (for a given SADM design) the higher the voltage the higher the risk. The maximum operating voltage of an APR based on Series Regulation is close to the open circuit voltage of the Solar Array and, thus, the arcing risk is usually present. This approach also avoids latching protections within the solar array regulator.
Under partial shading conditions, multiple peaks are observed in the power–voltage ( P– V) characteristic curve of a photovoltaic (PV) array, and the conventional maximum power point tracking (MPPT) algorithms may fail to track the global maximum power point (GMPP). Therefore, this paper proposes a modified incremental conductance (Inc Cond) algorithm that is able to track the GMPP under partial shading conditions and load variation. A novel algorithm is introduced to modulate the duty cycle of the dc–dc converter in order to ensure fast MPPT process. Simulation and hardware implementation are carried out to evaluate the effectiveness of the proposed algorithm under partial shading and load variation. The results show that the proposed algorithm is able to track the GMPP accurately under different types of partial shading conditions, and the response during variation of load and solar irradiation are faster than the conventional Inc Cond algorithm. Hence, the effectiveness of the proposed algorithm under partial shading condition and load variation is validated in this paper.
Multiple photovoltaic (PV) modules feeding a common load is the most common form of power distribution used in solar PV systems. In such systems, providing individual maximum power point tracking (MPPT) schemes for each of the PV modules increases the cost. Furthermore, its v-i characteristic exhibits multiple local maximum power points (MPPs) during partial shading, making it difficult to find the global MPP using conventional single-stage (CSS) tracking. To overcome this difficulty, the authors propose a novel MPPT algorithm by introducing a particle swarm optimization (PSO) technique. The proposed algorithm uses only one pair of sensors to control multiple PV arrays, thereby resulting in lower cost, higher overall efficiency, and simplicity with respect to its implementation. The validity of the proposed algorithm is demonstrated through experimental studies. In addition, a detailed performance comparison with conventional fixed voltage, hill climbing, and Fibonacci search MPPT schemes are presented. Algorithm robustness was verified for several complicated partial shading conditions, and in all cases this method took about 2 s to find the global MPP.
The perturb and observe (P&O) best operation conditions are investigated in order to identify the edge efficiency performances of this most popular maximum power point tracking (MPPT) technique for photovoltaic (PV) applications. It is shown that P&O may guarantee top-level efficiency, provided that a proper predictive (by means of a parabolic interpolation of the last three operating points) and adaptive (based on the measure of the actual power) hill climbing strategy is adopted. The approach proposed is aimed at realizing, in addition to absolute best tracking performances, high robustness and promptness both in sunny and cloudy weather conditions. The power gain with respect to standard P&O technique is proved by means of simulation results and experimental measurements performed on a low power system. Besides the performance improvements, it is shown that the proposed approach allows possible reduction of hardware costs of analog-to-digital (A/D) converters used in the MPPT control circuitry.
A stability analysis for a maximum power point tracking (MPPT) scheme based on extremum-seeking control is developed for a photovoltaic (PV) array supplying a dc-to-dc switching converter. The global stability of the extremum-seeking algorithm is demonstrated by means of Lyapunov's approach. Subsequently, the algorithm is applied to an MPPT system based on the "perturb and observe" method. The steady-state behavior of the PV system with MPPT control is characterized by a stable oscillation around the maximum power point. The tracking algorithm leads the array coordinates to the maximum power point by increasing or decreasing linearly with time the array voltage. Off-line measurements are not required by the control law, which is implemented by means of an analog multiplier, standard operational amplifiers, a flip-flop circuit and a pulsewidth modulator. The effectiveness of the proposed MPPT scheme is demonstrated experimentally under different operating conditions.
With rapid developments in the satellite data services market, the demand for low Earth orbit (LEO) satellites is increasing. Advancements in designing lightweight satellites are essential to maximize profits from the mass production of LEO satellites in private companies. This paper proposes a new direct charging control suitable for electrical power systems for lightweight and highly reliable LEO satellites. Moreover, an analysis of the proposed solar array regulator (SAR) in terms of weight, efficiency, and reliability is presented. Additionally, the advantages of the proposed SAR in terms of lifespan and state of health (SOH) of Li-ion batteries are presented because the peak value of the battery charging current and the temperature changes during the battery charging operation are relatively small.
In recent years, there is a growing interest in small satellites for deep space exploration. The current approach for planetary navigation is based on ground-based radiometric tracking. A new era of low-cost small satellites for space exploration will require autonomous deep space navigation. This will decrease the reliance on ground-based tracking and provide a substantial reduction in operational costs because of crowded communication networks. In addition, it will be an enabler for future missions currently impossible. This review investigates available deep space navigation methods from an autonomy perspective, considering trends in proposed deep space small satellite missions. Autonomous crosslink radiometric navigation, which is one of the best methods for small satellites due to its simplicity and the use of existing technologies, is studied, including available measurement methods, enabling technologies, and applicability to the currently proposed missions. The main objective of this study is to fill the gap in the scientific literature on the autonomous deep space navigation methods, deeply for crosslink radiometric navigation and to aim at showing the potential advantages that this technique could offer to the missions being analysed. In this study, a total of 64 proposed deep space small satellite missions have been analysed found from a variety of sources including journal papers, conference proceedings, and mission websites. In those missions, the most popular destinations are found to be cislunar space and small bodies with the purpose of surface mapping and characterization. Even though various autonomous navigation methods have been proposed for those missions, most of them have planned to use the traditional ground-based radiometric tracking for navigation purposes. This study also shows that more than half of the missions can benefit from the crosslink radiometric navigation through the inter-satellite link.
This article proposes the design and implementation of an electrical power system (EPS) for 2U CubeSat using a single-ended primary-inductor converter (SEPIC) along with the perturbed and observe method for the maximum power point tracking (MPPT). SEPIC converters have the advantages of input current continuity, voltage boosting and bucking, short-circuit protection, low-side driver, and noninverted input and output voltages. When the battery voltage is too low, by adding a low power consumption latching relay to develop a novel topology, the battery can be directly charged with solar panels without the MPPT algorithm and to improve the system reliability. In addition to the on-board computer subsystem, we can independently control whether to turn
on
the power according to the battery capacity and importance priority for each subsystem of CubeSat. The satellite is operated in outer space that the environment is wide temperature variation, vacuum, and high electromagnetic radiation. Therefore, the satellite was subjected to various types of tests, such as vacuum, thermal cycling, and radiation tests, to verify the system's capacity for enduring the aforementioned environmental changes. Finally, implementations and various tests were carried out to verify the viability and the accuracy, and reliability of the EPS of the satellite.
In 2021, the DART spacecraft will be launched by NASA to intercept the binary system Didymos and impact the moonlet (Dimorphos), to test the effectiveness of kinetic impactors for the deviation of hazardous asteroids’ trajectories. The impact is expected to generate a cloud of particles, whose study could provide valuable data about asteroid’s properties and impact models. Observations from ground to characterize ejecta and plume evolution after impact would be possible, but the resulting quality would be significantly lower than a short-range imaging. In this framework, ASI (Italian Space Agency) and NASA started a collaboration to embark on the US DART vehicle the LICIA (Light Italian CubeSat for Imaging Asteroid) 6U CubeSat as a piggyback payload. LICIA is devoted to grasp science data by imaging the ejecta plume after the impact, and observe Dimorphos surface while flying by the binary system. The Italian consortium involved in the mission sees ARGOTEC for the platform development, and INAF, Politecnico di Milano and Università di Bologna to cover the mission science, trajectory design and orbit de-termination tasks, respectively. The paper focuses on the mission analysis and maneuvers design, strongly driven by the science return, under the tight constraints enforced by the platform. In particular, it describes the preliminary procedure followed to derive trajectory constraints and to select the best option for the flyby. Despite the mission is still under development, and subjected to frequent updates of several parameters, the final performances derived in this paper maintain their validity as they represent the desired target values for the mission.
A simple multiplier for the estimation of the power yield of a solar panel may be realized with a pulse-width-modulator working as analog multiplier circuit. Though the output of the pulse width modulator multiplication is not proportional to the output power of the solar panel, it will be shown that its maximum follows the maximum of the power curve of the panel. The multiplier allows a complete analog implementation of the maximum power point tracker of the panel thus keeping the simplicity needed in robust electronic systems. This paper presents the working principle of the maximum power point regulator, its design procedure and a practical implementation for a low power solar panel using in small satellite platform applications.
This paper describes the implementation of a reliable maximum power point tracking design as an analog circuit for use on a satellite relying on solar power generation within low Earth orbit. The environment in which such a spacecraft system would function is evaluated. A specific maximum power point tracking algorithm is selected with regards to environmental constraints. A further increase in reliability was achieved by only using carefully selected analog components that are suitable for use within a space environment. The system was prototyped, and its power conversion performance was characterized using a custom-built measurement setup. The system successfully tracked the maximum power point through all the performed measurements. The results from the measurements suggest that the prototyped system has a nominal regulator efficiency of 88% and a nominal tracking accuracy of 96%.
Field-programmable gate arrays (FPGAs) have been shown to provide high computational density and efficiency for many computing applications by allowing circuits to be customized to any application of interest. FPGAs also support programmability by allowing the circuit to be changed at a later time through reconfiguration. There is great interest in exploiting these benefits in space and other radiation environments. FPGAs, however, are very sensitive to radiation and great care must be taken to properly address the effects of radiation in FPGA-based systems. This paper will highlight the effects of radiation on FPGA-based systems and summarize the challenges in deploying FPGAs in such environments. Several well-known mitigation methods will be described and the unique ability of FPGAs to customize the system for improved reliability will be discussed. Finally, two case studies summarizing successful deployment of FPGAs in radiation environments will be presented.
The power–voltage characteristic of photovoltaic (PV) arrays operating under partial-shading conditions exhibits multiple local maximum power points (MPPs). In this paper, a new method to track the global MPP is presented, which is based on controlling a dc/dc converter connected at the PV array output, such that it behaves as a constant input-power load. The proposed method has the advantage that it can be applied in either stand-alone or grid-connected PV systems comprising PV arrays with unknown electrical characteristics and does not require knowledge about the PV modules configuration within the PV array. The experimental results verify that the proposed global MPP method guarantees convergence to the global MPP under any partial-shading conditions. Compared with past-proposed methods, the global MPP tracking process is accomplished after far fewer PV array power perturbation steps.
Perusal of the V-I characteristics of commercial solar panels with insolation, ambient temperature, and production spreads as parameters, indicates that the maximum power is obtained from such a panel when it is loaded to a working voltage that is a fixed percentage of its open circuit voltage within plus or minus 2 percent. This contribution describes a system that uses this characteristic to achieve maximum power control by determining the open circuit voltage and automatically loading the panel to the maximum power point as applied to a battery charging installation. The description includes the application of a novel modified Darlington circuit to boost the efficiency of a pulse width controlled switch mode type regulator by reducing the Darlington saturation voltage by a compensating voltage. Advanced switching technology is applied to reduce switching losses, and maximize efficiency.
The voltage-current characteristic of solar cells that provide power for a spacecraft can vary over a wide range. For maximum power transfer from the solar cells to the battery system a power converter has to be designed that adjusts its input impedance to a value equal to the output impedance determined by the operating power characteristic of the solar cells. This paper discusses a circuit and calculations for a design to match this condition. The proposed power converter is simple, lightweight, and reliable and will be used in the Sunblazer satellite.
A high performance, very low cost power system for microspacecraft
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Micro-platform power system for scientific deep space exploration
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Solar array hysteresis and its interaction with the MPPT system
- fernandez
Exploring the use of the LT3480 (RH3480) circuit as low-power, low-voltage solar array regulator
- garrigós
A high performance, very low cost power system for microspacecraft
- C Clark
- A Strain
- A López-Mazarias
Solar array hysteresis and its interaction with the MPPT system
- A Fernandez
- C Baur
- F Gómez-Carpintero
Exploring the use of the LT3480 (RH3480) circuit as low-power, low-voltage solar array regulator
- A Garrigós
- J L Lizán
- J M Blanes
- R Gutiérrez
A new technique for tracking the global maximum power point of PV arrays operating under partial-shading conditions
- E Koutroulis
- F Blaajberg