Modern spacecraft increasingly demand high-voltage buses for high-power loads, yet raising solar array (SA) voltage drives risks and qualification costs. This article proposes a dual-bus power architecture that provides a higher voltage bus alongside a lower voltage battery bus without imposing higher voltage requirements on the SA. The SA is series-connected with the battery to enable direct energy transfer (DET) from the SA to the higher voltage bus, while a single bidirectional DC/DC converter, connected in series partial power processing, regulates the higher voltage bus, and, in unregulated-bus mode, executes maximum power point tracking (MPPT). Because the higher voltage bus is tightly regulated by the DC/DC converter, MPPT dynamics are decoupled from bus impedance during load transients, preserving bus-voltage stability. Processing only a fraction of the differential power between load demand and the SA's DET contribution reduces processed power, converter rating, mass, and losses. An analytical model of the architecture is derived, and a laboratory prototype validates the model, the operating principle, and SA-bus decoupling with experimental measurements that closely match theory.

This paper proposes a transformerless, capacitively isolated inverter employing a full-bridge topology. Unlike conventional capacitively isolated converters, the proposed design eliminates the mean voltage across the isolation capacitors, significantly reducing voltage stress. A previous experimental validation of a capacitive isolated DC/DC converter demonstrated operation at switching frequencies up to 500 kHz and power levels of 6 kW (500 V, 12 A), achieving a peak efficiency exceeding 98% with negligible loss contribution from the isolating capacitors. Building on these results, the topology is extended to a single-stage inverter to leverage capacitive isolation for loss minimization. The inverter design was simulated, and key operating waveforms are presented to validate its functionality. Analysis of the DC/DC converter assessed the rectifying diodes as dominant contributors to power losses at elevated switching frequencies and are omitted in the inverter stage. This elimination, combined with the minimal impact of isolating capacitors, enables a projected inverter peak efficiency exceeding 99%, as derived from experimental data and analytical modeling.

This paper proposes a novel approach for mitigating cross-regulation errors in multi-output flyback converters by integrating a balancing capacitor. The approach establishes a low-impedance path between the transformer’s secondary windings, equalizing node voltages and reducing reducing load imbalance effects. Experimental validation on a prototype demonstrates significant mitigation of cross-regulation errors, with the balancing capacitor maintaining a negligible average voltage drop. Results reveal that residual output offsets under unbalanced loads stem primarily from differences in the forward voltages of the rectifying diodes. The analysis is extended to a multi-output flyback topology delivering balanced positive and negative outputs, confirming the method’s applicability to multi-output configurations. These findings underscore the versatility and effectiveness of the proposed strategy for improving cross-regulation in low-power industrial applications.

This article proposes a transformerless, capacitively isolated converter based on a full-bridge topology with phase shift control. Compared to the existing capacitively isolated converters, the proposed design offers the advantage of zero mean voltage across the isolating capacitors, thereby reducing voltage stress. A comprehensive analytical model is developed to describe the converter's operation in both continuous and discontinuous conduction modes. The model is validated through an experimental prototype tested at power levels up to 6 kW and switching frequencies up to 500 kHz, achieving a peak conversion efficiency exceeding 98%. The experimental results confirm the accuracy of the theoretical model and waveforms.

This paper presents a comprehensive investigation of the performance of an electric drive powered by an asymmetric cascaded H-bridge multilevel inverter coupled with an interior permanent magnet synchronous motor (IPMSM). Different modulation strategies are evaluated and compared with a proposed hybrid technique to investigate the advantages of each method. Simulation results are used to assess dynamic behavior and harmonic performance, with a focus on total harmonic distortion and waveform quality. The findings demonstrate that the hybrid modulation approach achieves a better balance between efficiency and harmonic content, making it particularly well-suited for applications requiring rapid dynamic response and high-power quality, such as electric mobility.

IntroductionAstroBio CubeSat (ABCS) is an Italian Space Agency (ASI) 3U CubeSat (100x100x340 mm) selected by European Space Agency (ESA) to be launched with the Vega C qualification maiden flight, as piggy back of the ASI LARES2 main satellite, by the end of 2020. ABCS will be deployed in an approximately circular orbit, with about 5900 km altitude and 70° of inclination. It implies that ABCS will spend a significant part of the orbital period within the internal Van Allen belt, close to its maximum. The radiation environment is characterized by a very high flux of charged particles, which have a significant effect on electronic components in terms of permanent damages due to accumulated dose effects and single events. Considering the extremely harsh space conditions, the estimated mission lifetime useful to perform the payload experiments should be defined in 3 months.ABCS Project is funded and managed by ASI in cooperation with INAF-Astrophysical Observatory of Arcetri, that will coordinate the scientific and engineering team. Partners of the projects are the School of Aerospace Engineering of Sapienza University of Rome, the University of Bologna, the University of Torino, and Kayser Italia.ABCS PayloadABCS will host a mini laboratory payload based on an innovative lab-on chip technology suitable for research in astrobiology. The objective is to test in space environments an automatic laboratory able to provide a highly integrated in-situ multiparameter platform that uses immunoassay tests exploiting chemiluminescence detection by means of on-chip a-Si:H photodiodes. The experiment will consist in a set of lateral flow immunoassays (LFIA) on nitrocellulose support where target biomolecules are immobilized in specific test areas. Reagents are deposited in a non-permanent fashion and in a dry form in the initial part (starting area) of the microfluidic path. When the reagents-delivery-system provides a volume of liquid reagent to the starting pad, capillary forces will guide the reagents through the LFIA microfluidic pathway. During the flow, liquid reagents will solubilize and transport along the path the deposited reagents, triggering specific reactions and allowing the chemiluminescence detection by the photodiodes.ABCS also mounts an ancillary radiation dose payload, to investigate the degradation of of electronic components exposed to the space environment. The device has twin components protected by established radiation screens, kindly provided by Thales Alenia Space Italia and by CESI, so that the degradation can be assessed on the basis of the difference between the observed currents.ABCS architecture and payload are based on the strong heritage gained by the research team with the ground validation of the PLEIADES (Planetary Life Explorer with Integrated Analytical Detection and Embedded Sensors) instrument, an R&D ASI project recently concluded.Enviromental challengesThe main challenges of the project are to mitigate the effects of the expected very high flux of charged particles, keeping the correct temperature (4°C/25°C) and pressure (about 1 atm) range for the payload to prevent reagents degradation. This invoked a series of technological solution to protect the payload. The pressurized environment is ensured by an inner aluminium box, hosting both the experiment and the main subsystems (batteries, on-board data handling, telemetry, tracking and control) hermetically sealed and providing shielding from radiation and charged particles. A thermal control system, including a passive control multi-layer insulation and an active heather mounted inside the pressurized box, maintain the temperature in the desired range.ConclusionABCS mission aims at evaluating the overall system functionality (delivery of reagents, mixing of chemicals, LoC characterization, detection of emitted photons, readout noise, etc.) such as the chemicals and biomolecules stability (reagents and antibodies employed in the experiment) in the extremely harsh environment.The in-orbit validation of the proposed technology would represent a significant breakthrough for autonomous execution of bio-analytical experiments in space with potential application in search for signs of life in planetary exploration missions, space biolabs without human support, health monitoring in manned missions.

This paper addresses cross-regulation in dual-output flyback converters. An original analytical framework is developed to model the impact of a balancing capacitor connected among a transformer’s secondary windings in order to mitigate the cross-regulation among different outputs. To validate the proposed model, a prototype dual-output flyback converter was built and tested for a wide range of load unbalances. The measured cross-regulation error was compared with the theoretical predictions provided by the proposed model, obtaining a tight fit, which confirms the validity of the proposed approach.

Introduction Astrobiology is an interdisciplinary field covered by only a few CubeSat missions so far. Moreover, no CubeSat mission has ever mounted miniaturized technology for the purpose of searching for molecular evidences of life in space. AstroBio CubeSat (ABCS) is a 3U CubeSat selected by the European Space Agency (ESA) to be launched in spring 2022 with the Vega C maiden flight, as piggy back passenger of the ASI LARES2 mission. ABCS will host a payload assembly based on Lab-on-Chip (LoC) technology for biomarkers detection and will be deployed along a circular orbit with altitude of about 5900 km and inclination of 7°, therefore crossing the inner Van Allen belt where the radiation flux is close to its maximum. Due to the harsh environment, ABCS payload and subsystems will be likely exposed to damages and degradations of electronics and performances, thus the payload assembly and the operational architecture were designed to be as much dependable as possible. This approach should constitute the first step to implement a mature technology with the aim to check the stability of chemicals and biomolecules involved in space experiments. This work reports an overview of ABCS architecture and the approach chosen for its operational design. ABCS Architecture ABCS objective is to test in space an automatic in-situ multiparameter LoC [1], which exploits luminol injection and enzymatic bio-mimicking assays on a functionalized 3D wax-printed origami. Luminol will be transported by capillarity to reaction sites with immobilized biomolecules targets where the reactions will trigger chemiluminescence, detected by means of hydrogenated amorphous silicon (a-Si:H) photodiodes deposited on a borosilicate glass substrate and connected to a photocurrent readout board [2]. The described payload consists in an experiment board hosting the LoC and a support board containing peristaltic pumps for luminol injection, drivers for pumps, radiation field effect transistors (RADFETs) and pressure/temperature sensors. The LoC architecture allows to repeat the experiment up to six times. In addition to RADFETs, ABCS mounts an ancillary radiation dose sensor (ARDS), developed by Thales Alenia Space, with the aim to assess the radiation effects. The ARDS is able to measure different amounts of current, until its failure, depending on the dose acquired. To mitigate the effects of the expected very high flux of charged particles, an extra tungsten layer shielding was mounted on each side panel and all the main subsystems (experiment and support board, batteries and EPS board, on-board computer (OBC), telemetry, tracking and control board), were placed inside a 5 mm thick aluminium box. At the same time, to keep the temperature range (from 4°C to 20°C) and operative pressure (about 1 atm) required to allow the LoC capillarity effect and to prevent reagents degradation, the box was sealed and a thermal control system, composed by a multi-layer insulation and an active heather mounted inside the box, was implemented. ABCS Mission Design ABCS will be deployed in an approximately circular orbit at about 5900 km altitude and 70° of inclination, spending a significant amount of the orbital period within the inner Van Allen belt, very close to its radiation peak point. ABCS ground operations will be mainly performed from the School of Aerospace Engineering (SIA) Ground Station. Simulations show that SIA will have access to ABCS 4 times a day, with an average duration of about 65 minutes. For this reason, a network of radioamateurs and third part ground stations will be involved for supporting the collection of the telemetry and science data packages and possibly uplink commands. ABCS Operations The assumption we made is that ABCS should be able to perform the payload operations in a completely autonomous manner. As we know, radiation flux will most likely induce several errors on electronics and performances, causing potential mission failure due to the fact that payload operations may not start because the OBC fails to send the command to start the experiment. A possible way to reduce failure is to perform ABCS experiments where the proton flux is lower. Simulations shows that this happens when ABCS is at polar latitudes, namely outside the range [-60°; 60°]. For this reason, the payload operations, based on redundant checks and triggers, were implemented accordingly. The purpose is to automatically determine if ABCS is at a latitude useful to perform the experiments and verifying this condition by means of multiple triggers, time or position based. Each trigger is used for scheduling purposes only if the ones with higher priority are unreliable. If all the triggers are not reliable, payload operations are forced to begin, as it is better to perform eventually degraded payload operations rather than performing no payload operations at all. Conclusions ABCS is required to operate in an extremely harsh environment where radiation fluxes are likely to degrade the electronic devices. Operations should be scheduled in order to reduce the time needed to perform all the experiments. The chosen approach will lead ABCS to complete the payload operations in three orbital periods, reducing the total ionizing dose absorbed and guaranteeing the higher system reliability. Acknowledgments ABCS AstroBio-CubeSat is supported by ASI - Italian Space Agency ASI/INAF Agreement n. 2019-30-HH.0. References [1] Iannascoli, L. et al. 2020, "Astrobio cubesat: Enabling technologies for astrobiology research in space", Proceedings of the International Astronautical Congress, IAC. [2] Mirasoli M, et al. 2014. Multiwell cartridge with integrated array of amorphous silicon photosensors for chemiluminescence detection: development, characterization and comparison with cooled-CCD luminograph. Anal Bioanal Chem. Sep;406(23):5645-56.

A technique for managing power generation in a spacecraft power bus is introduced. The proposed technique is based on a sectional MPPT approach, where the solar array is split into several sections, interfaced to the power bus by dedicated Array Power Regulators. The dc-dc converter inside each of them is enslaved to a multimode controller, capable of selecting either MMPT or regulation mode or standby. The operating mode is managed in such a way that the rough regulation is achieved by sequentially increasing/decreasing the number of converters in MPPT according to the fluctuations of the power absorption on the bus, while the fine regulation is performed by a single converter in the regulation mode. Some possible configurations of the system are analyzed. Simulations of the algorithm and experimental results are provided.

Isolated power converters find application in different fields of electric mobility, such as battery charging, where galvanic insulation between on-board storage system and electrical grid is required. Conventional isolated systems are based on the use of transformers, which have the drawback to be bulky and expensive. Nevertheless, insulation implemented by capacitances can be attractive due to the recent technological advances, contributing to increasingly compact, cheap and efficient converters. In this paper, an isolated power converter based on capactive power transfer (CPT), along with the switched capacitor concept, is proposed. GaN FETs are employed as switching power devices in order to handle high operation frequencies with limited power losses. In this work a 500 kHz switching frequency has been selected, with notable benefits brought to the overall power converter in terms of compactness. The developed prototype has been experimentally tested according to a target power level of 3 kW, to prove the proper operation of the proposed converter. The experimental tests have demonstrated a power transfer efficiency as high as 95%.

Developing novel functional materials to advance the technological level of clean and renewable energy systems is the focus of much research. Due to their outstanding operational and compositional properties, perovskite-based structures have already been studied as an important class of solid-state components for electrochemical (EC), photoelectrochemical (PEC), and photovoltaic–electrochemical (PV-EC) CO2 reduction, showing great potential in their catalytic activity and device stability and with a promising window for further technological developments. In this review, the different kinds of perovskites in the context of their structural features, which lead to their different applications, are first investigated. Then, we summarize the recent progress in the use of perovskites in EC, PEC, and PV-EC CO2-reduction devices. The research demonstrates that the mechanism and kinetics of intermediate formation have a significant effect on the creation of the final product. Investigations show that appropriate surface modifications, such as through the use of doping agents, alloy construction, and composites, can considerably improve the electrocatalytic activity and stability of perovskites. Finally, the perspectives on, and limitations of, the commercial and large-scale production of perovskites for CO2 reduction are stated.

Preliminary results of the in-orbit characterization of an analytical payload based on a lab-on-chip device with integrated thin-film photosensors relying on chemiluminescence immunoassay is presented. The paper addresses the characterization of the main components of the analytical system based on data acquired during the AstroBio CubeSat mission launched aboard the Vega-C maiden flight in summer 2022. In particular, the performances of the on-chip thin-film sensors and the lab-on-chip front-end readout electronics are reported in detail confirming the suitability of the proposed technology for space application.

Small satellites are known to provide low-cost access to space, enabling fast and cheap validation of new technologies for space missions. ASTROBIO is a 3U CubeSat (size 100xl00x300 mm3), that was injected into an orbit crossing several times a day the cloud of radiation known as the Van Allen Belts. As a result, the solar panels are exposed to an enhanced dose rate and undergo in a few days the same degradation that would be observed after several years of space flight in Low Earth Orbit. We used this unique opportunity to validate the new End-Of-Life optimized Triple Junction solar cells (CTJ-EOL) produced in Italy by CESI. The spacecraft solar panel comprises two types of solar cells produced by the same manufacturer: the well-established CTJ-30 and the new CTJ-EOL. Their performance was separately monitored and the related telemetries were downloaded for off-line elaboration. This manuscript reports and analyses the telemetries received by our Ground Station and by the networked stations distributed all over the globe. Data analysis clearly and unequivocally demonstrated the superior ruggedness of the End-Of-Life optimized devices: in the first week, the CTJ-30 performance dropped like it would be expected along a 10-years+ mission in the most-commonly-used orbits, whereas degradation of the CTJ-EOL was barely detectable. The results also show that in-orbit testing can provide unique information about the operation of solar cells in the intended operational environment as well as an easy verification of the device's functionality, useful to complement standard characterization procedures for radiation hardness involving costly and time-consuming laboratory tests under particle beams.

AstroBio CubeSat is a mission funded by the Italian Space Agency aimed at validating novel lab-on-chip technology, that would enable the use of micro- and nanosatellites as autonomous orbiting laboratories for research in astrobiology. This 3U CubeSat is equipped with a passive magnetic attitude control system (PMACS), including permanent magnets and hysteresis strips, which allows for stabilizing the spacecraft with the longitudinal axis in the direction of the geomagnetic field vector. This work presents the process followed for the experimental characterization of the system, performed on the engineering unit of the satellite by using a Helmholtz cage facility and a spherical air-bearing to recreate environmental conditions similar to the ones experienced during the orbital motion. The hysteresis strips are characterized starting from the determination of the hysteresis loop, from which the energy dissipation per cycle and the apparent magnetic permeability are extracted. Tests performed by using the Helmholtz cage and the air-bearing facility allows for further investigating the damping torque produced by the PMACS and validating the abovementioned parameters. Numerical analysis is then used to select the number of permanent magnets which allows for achieving a pointing accuracy within an error of 10∘ within 24 h from the deployment. The analysis of the flight data supports the results obtained from the experimental test campaigns, confirming the effectiveness of the proposed methods and of the PMACS design.

This paper proposes an isolated Switched Capacitor (SC) power converter which provides galvanic isolation through Capacitive Power Transfer (CPT). The combination of these two technologies might answer for electrical and power requirements in different electrical mobility application fields, such as battery charging. Accordingly, due to the low conversion losses the combination of these two technologies can provide, compact, cost effective and highly efficient power converters can be derived, thus potentially answering the scalability requirements for the Electric Vehicles (EV) market. To assess the operation of the proposed circuital solution, a Full Bridge (FB) CPT isolated interfacing converter prototype has been designed and built. Since GaN switches were used for the primary bridge, by taking advantage of their low input capacitance and gate charge, a 500 kHz switching frequency was set, thus deriving a compact power converter. The prototype has been designed for applications up to 12 kW (600 V, 20 A), and tested close to 3 kW (up to 400 V or 15 A) for the purpose of this work to demonstrate its functionality. The measurements assessed a conversion efficiency above 90% with a peak of almost 95%.

The inherently intermittent nature of photovoltaic (PV) energy has brought increasing interest towards the integration between PV sources and Battery Energy Storage Systems (BESS). In this paper, a Series Partial Power Processing (PPP) converter based on Capacitive Power Transfer (CPT) is proposed to integrate PV and BESS in a grid-connected inverter system. The proposed converter has been simulated according to a PV string capable to provide 1430 W under full irradiance conditions, a BESS nominal voltage equal to 215 V and a solar inverter assumed to operate with a minimum voltage of 150 V and a maximum current of 10 A. Simulation tests carried out at different conditions of solar radiation and required load power aim at demonstrating the correct operation of the proposed system.

Triple junction solar cells based on InGaP/GaAs/Ge are the baseline for the space application. This paper reports the achievement in terms of development, characterization and in-flight experience for two new concepts of multijunction solar cells developed at CESI and experimented on board of a cubesat developed at Sapienza University: the triple junction solar cells with integral assembly (CTJ-AI) and the triple junction solar cells with enhanced resistance against radiation (CTJ-EOL).

In space vehicles, the typical configurations for the Solar Array Power Regulators in charge of managing power transfer from the solar array to the power bus are quite different from the corresponding devices in use for terrestrial applications. A thorough analysis is reported for the most popular approaches, namely Sequential Switching Shunt Regulation and parallel-input Pulse Width Modulated converters with Maximum Power Point Tracking. Their performance is compared with reference to a typical mission in low Earth orbit, highlighting the respective strengths and weaknesses. A novel solar array managing technique, the Sequential Maximum Power Tracking, is also introduced in the trade-off and was demonstrated able to boost energy harvesting, especially in the presence of mismatching in the solar array. It also can achieve top levels of reliability using a rather simple control hardware. Its operation was verified both by a Matlab–Simulink model and by an experimental breadboard.

Nowadays, an increasing electrification level is being addressed towards different sectors, such as transportation and industrial electronics. To bear that, high speed electrical machines represent a mature technology in different application fields, e.g. avionics, automotive, compressors and spindles. In order to guarantee high speed while keeping high power quality without adopting bulky filtering circuits, DC-AC converters shall be controlled by means of high Pulse Width Modulation (PWM) frequencies. In addition to the emerging switching device technologies, such as those based on Silicon-Carbide (SiC) and Gallium-Nitride (GaN), alternative circuital topologies are crucial in order to comply with the higher switching frequencies while maintaining high voltage levels. The Cascode (CC) structure represents an attractive topology for those applications. In this paper a three phase inverter based on CC devices is investigated, by simulating a 400 Hz sinusoidal PWM. Experimental results showing the satisfactory operation of a single-switch DC-AC implemented through a CC architecture are provided as well.